Long Term Effects of Spay Neuter
Long Term Effects of Spay Neuter
Opinion of Theriogenologists
Position Statement on Mandatory Spay-Neuter
The American College of Theriogenologists and The Society for Theriogenology believe that companion animals not intended for breeding should be spayed or neutered; however, both organizations believe that the decision to spay or neuter a pet must be made on a case by case basis, and this decision should be made between the pet’s owner and its veterinarian, taking into consideration the pet’s age, breed, sex, health status, intended use, household environment and temperament.
While there are health benefits to spaying and neutering these must be weighed against the health benefits of the sex steroids. In general, the advantages of spaying or neutering a pet include effective population control,decreased aggression, decreased wandering, decreased risk of being hit by a car, and decreased risk of mammary, testicular and ovarian cancer. On the other hand, the disadvantages of spaying or neutering may include increased risk of obesity, diabetes, osteosarcoma, hemangiosarcoma, prostatic adenocarcinoma, transitional cell carcinoma, urinary tract infections, urinary incontinence, autoimmune thyroiditis, hypothyroidism and hip dysplasia. Therefore, the decision to spay or neuter a dog or cat should be made solely by the pet’s owner with the direct input of their veterinarian and will be dependent on each particular animal’s situation.
Additionally, research has shown that in locations where mandatory spay and neuter programs have been instituted, a decrease in the number of vaccinated and licensed animals has been seen due to poor program compliance from pet owners’ fears of seeking veterinary care if their animals are still intact. This may result in decreased preventive care and regular wellness examinations which may then diminish the pet’s quality of life because of increasing undiagnosed health issues. It also may result in an increase in zoonotic diseases, such as hookworm and roundworm infection in children due to poor deworming programs, and decreased compliance with routine rabies vaccination.
The ACT and SFT make the following recommendations to continue moving toward effective methods of reducing the number of abandoned, unwanted and euthanized dogs and cats in the US and other countries where similar problems exist.
1) Provide increased jurisdictional control to the AVMA Governmental Relations division, Animal Welfare
Committee, and the APHIS-Animal Care division.
2) Ensure suppliers to pet stores are providing adequate care for breeding stock and offspring.
3) Support programs to expand the public awareness of pet overpopulation, acceptable breeding standards,
and responsibilities of pet ownership. Provide the public a means to access assistance with concerns
of pet health, ownership, behavior and management issues.
4) Work with state and local rescue and humane societies to assemble accurate data on causes for
relinquishment of dogs and cats to enable these organizations, federal and local governments, and veterinary
organizations to address the fundamental causes of abandonment.
5) Provide low cost spay/neuter facilities for economically disadvantaged persons and communities.
6) Continue to work on reduction of feral cat populations.
7) Establish programs to ensure access of breeders to proper reproductive care and counseling.
8) Provide local or federal governmental assistance to registered rescue organizations to facilitate
placement of unwanted pets.
Society for Theriogenology Home Page http://www.therio.org/displaycommon.cfm?an=1&subarticlenbr=193
Copyright © 2007 - 2008 Society for Theriogenology. All rights reserved.
Basis for Position on Mandatory Spay-Neuter in the Canine and Feline
The American College of Theriogenologists (ACT) is the certifying college for veterinarians board certified in
reproduction (specialists) and the Society for Theriogenology (SFT) is an organization of veterinarians with a special interest in reproduction in veterinary medicine. The ACT and SFT believe that companion animals not intended for breeding should be spayed or neutered; however, both organizations believe that the decision to spay or neuter a pet must be made on a case by case basis, taking into consideration the pet’s age, breed, sex, intended use, household environment and temperament. The use of generalized rules concerning gonadectomy (removal of the ovaries or testes) is not in the best interest of the health or well-being of the pets or their owners. Each of the following considerations must be assessed for each individual animal and household.
1) Health concerns
a. Research has shown that there can be positive effects of the sex steroid hormones. The sex
steroids are hormones produced by the ovaries and testes, and are only present in intact males and
females. Gonadectomy at any age deprives the body of the positive health effects of these
hormones. Although in most cases, the benefits of spay-neuter outweigh the benefits of exposure to
the sex steroids, this is not true in all cases. Since gonadectomy prior to puberty or sexual maturity
may make the risks of some diseases higher in certain breeds or individuals, the option to leave an
animal intact must be available to the pet owner.
i. Advantages of remaining intact:
1. There is a decreased incidence of hemangiosarcoma in intact bitches and dogs.
2. There is a decreased incidence of osteosarcoma in intact male and female dogs.
3. There is a decreased risk of transitional cell carcinoma in intact dogs and bitches.
4. There is a decreased risk of prostatic adenocarcinoma in intact male dogs compared
to gonadectomized male dogs.
5. There is a decreased incidence of obesity in intact male and female dogs and cats,
which may be due at least partly to increased metabolic rate.
6. There is a decreased incidence of urinary incontinence in intact bitches (equivocal if
bitches are spayed after 5 months but before their first heat).
7. There may be a reduced incidence of urinary tract infection in intact bitches.
8. There may be a reduced incidence of feline lower urinary tract disease (FLUTD) in
intact male and female cats which may be partly due to decreased obesity in these
animals.
9. There may be a reduced incidence of autoimmune thyroiditis and hypothyroidism in
intact male and female dogs.
10. There is a decreased incidence of diabetes mellitus in intact female cats and a
possibly reduced incidence in diabetes mellitus in intact male dogs.
11. There is a reduced incidence of cranial cruciate rupture in intact male and female
dogs.
12. There may be a reduced incidence of hip dysplasia in male and female dogs that are
not gonadectomized before 5 months of age.
13. There may be an increased incidence of capital physeal fractures in castrated male
cats that may be partially due to increased weight gain in gonadectomized males.
b. Research has shown that there are a number of detrimental effects of the sex steroid hormones.
Spaying and neutering will remove these hormones and thus lower the risk of these conditions.
i. Advantages of being spayed or castrated:
1. There is an increased risk of mammary, testicular, and ovarian neoplasia in intact
male and female dogs and cats.
a. There is an increased risk of mammary cancer with each subsequent cycle
and the benefit of spaying does not disappear until the animal reaches old age.
i. Mammary cancer is one of the most common types of neoplasia in small animals.
1. Mammary neoplasia is malignant 60% of the time in dogs and 90% of the time in cats.
b. The incidence and mortality risk for ovarian cancer are very low
c. The incidence for testicular cancer is more common but malignancy and mortality are very low.
2. There is an increased risk of pyometra in both intact female dogs and cats and this risk increases with increasing age.
3. There is an increased risk of prostatitis, benign prostatic hyperplasia, prostatic cysts and squamous metaplasia of the prostate in intact male dogs.
4. There is a decreased incidence of perineal and inguinal hernia and perineal adenoma in neutered male dogs.
c. Based on the research available, it is clear there are a number of health benefits of the sex steroid hormones and that this benefit varies with age, sex, and breed. Therefore, although spay-neuter is the responsible choice for most pets, it is in the best interest of each individual patient for its veterinarian to assess the risks and benefits of gonadectomy and to advise his/her clients on what is appropriate for each individual pet at each stage of its life.
2) Behavioral concerns
a. Research has shown that there are positive effects of the sex steroid hormones on behavior.
i. Advantages of remaining intact:
1. There is a decrease in shyness and hiding behavior in intact male and female cats.
2. There may be less aggression towards people and animals in intact bitches.
3. There may be a decreased incidence of cognitive dysfunction in intact male and
female dogs.
b. Research has shown that there are negative effects of the sex steroid hormones on behavior.
i. Advantages of being spayed or castrated:
1. Inter-dog aggression may be due to competition for available territory or availability of cycling animals.
2. Urine spraying and inter-animal aggression is increased in intact male cats.
3. There is a decreased risk of wandering and being hit by a car in neutered animals.
3) Provision of quality medical care
a. It is not in the animals’ best interest to have the legislature dictate the time or need for surgical
treatment.
i. This does not allow for medical decisions based on the individual animal’s needs, its owners’ needs or the needs of the household.
1. Animals with medical conditions that may result in complications during anesthesia or surgery (i.e. heart murmurs, bleeding disorders).
2. Providing appropriate aftercare for surgical patients may not be feasible in some home situations.
b. Restricting and reducing the pool of purebred animals will greatly hinder medical research of
conditions that are particular to specific breeds, slowing down advances in medical and surgical
knowledge. This may in turn impact the research available concerning health conditions common to
both animals and people.
4) Public Health concerns
a. Making spay/neuter mandatory for licensure may make the public more hesitant to seek veterinary
assistance because they are afraid of fines and legal repercussions as a result of failing to spay or
neuter their pets by the prescribed time. By avoiding veterinary care for their pets, animals will be at
increased risk of inadequate routine vaccination (including rabies) and inadequate deworming
programs which may in turn result in increased transmission of disease to the public.
The ACT and SFT make the following recommendations to continue moving toward effective methods of
reducing the number of abandoned, unwanted and euthanized dogs and cats in the US and other countries where similar problems exist.
a. Provide increased jurisdictional control to the AVMA Governmental Relations division, Animal Welfare
Committee, and the APHIS-Animal Care division.
b. Ensure suppliers to pet stores are providing adequate care for breeding stock and offspring.
c. Support programs to expand the public awareness of pet overpopulation, acceptable breeding standards,
and responsibilities of pet ownership. Provide the public a means to access assistance with concerns
of pet health, ownership, behavior and management issues.
d. Work with state and local rescue and humane societies to assemble accurate data on causes for
relinquishment of dogs and cats to enable these organizations, federal and local governments,
and veterinary organizations to address the fundamental causes of abandonment.
e. Provide low cost spay/neuter facilities for economically disadvantaged persons and communities.
f. Continue to work on reduction of feral cat populations.
g. Establish programs to ensure access of breeders to proper reproductive care and counseling.
h. Provide local or federal governmental assistance to registered rescue organizations to facilitate
placement of unwanted pets.
The ACT and SFT do not believe that mandatory spay/neuter programs will significantly reduce the pet
overpopulation problems, since most animals that are abandoned are relinquished because of behavior, health,
economic and life changing conditions and not due to their reproductive status. In fact, in some European Union
countries where gonadectomy is illegal unless deemed medically necessary (such as Norway) there are no significant problems with pet overpopulation, indicating that the pet overpopulation problem that exists in the United States is due to cultural differences on the importance of pets, the responsibility of pet owners, and the ability of the government and national agencies to properly educate the public. Although both organizations believe that most companion animals should be spayed or neutered, the ACT and SFT also strongly believe that it is not in the best interest of the animals to produce legislation regarding medical treatments, Therefore, both organizations oppose mandatory spay/neuter programs.
There are hundreds of references which provide scientific information on the effects of spay and neuter in both dogs and cats. We chose to provide the reader with a selected list of them. This reference list was compiled by Dr. Peggy Root-Kustritz, DACT.
Copyright © 2007 - 2008 Society for Theriogenology. All rights reserved.
Report from Journal of AVMA
Optimum Age
Illinois State Veterinary Medical Association
Initially written for the Chicgo elected officials, this article contains a great deal of data on issues such as dog bites that the proponents of MSN misuse. Please read this, learn the facts and the sources.
The Illinois State Veterinary Medical Association (ISVMA) opposes the mandatory spay/neuter
ordinance being proposed for the City of Chicago. Although the ordinance’s stated goals to
reduce the number of unwanted pets and gang activity are laudable, the reality is that it will have
no effect on these problems. Instead, it will create some serious public health concerns, cause
many animals to be denied necessary health care, and will trample on the personal property
rights of conscientious pet owners.
The ISVMA opposes this proposed ordinance for the following reasons: (explanations below)
The ordinance implies that dog bites will vanish because of a simplistic, and non-
scientifically based assumption that only intact animals bite.
There is no conclusive evidence that mandatory spay/neuter programs work.
This mandate would discourage pet owners from seeking rabies immunization if they are
opposed to neutering/spaying and fear they will be reported. Currently, we struggle to
ensure the proper safeguards are in place to protect the public from rabies. Rabies is
essentially a 100% fatal disease to humans, dogs and cats.
There are not enough resources in Chicago to enforce this law in a meaningful way.
With regard to creating a healthier pet, there are both positive and negative affects
accrued from sterilization. It appears that benefits outweigh risks; however, there are
many breed and individual dog variants, suggesting that professional judgment is
required to determine whether and when to neuter/spay pets.
Unfortunately, evidence used to support several of the arguments in the ordinance has been
taken out of context and used to mislead. The statement that "...a 1991 study of medically
attended dog bites concluded that sexually intact dogs are 2.6 times more likely to bite than
neutered dogs..." is one example. We believe the article the ordinance’s authors intended to
reference is one available at: http://www.cdc.gov/ncipc/duip/dog3.pdf; it was actually published
in 1994. The statistic cited from this paper applies to intact male dogs, not t he more general
"sexually intact dogs" as described in the background of the ordinance. In fact, the authors of the
article acknowledged that spayed female dogs may have a greater tendency to bite than intact
female dogs.
The suggestion that dog bite injuries will vanish because of this law builds on a simplistic,
inaccurate, and potentially dangerous assumption that only intact animals bite. In fact, a study
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performed by researchers at the University of Pennsylvania in 2007 (Journal of Injury Preventi on
Oct;13(5):348-51), which looked at records of bites incurred by 111 children, yielded the
following results:
Children <6 years old were most commonly bitten in association with resource guarding
(44%), whereas older children were most commonly bitten in association with territory
guarding (23%).
Food guarding was the most common circumstance for bites to familiar children (42%) and
territory guarding for bites to unfamiliar children (53%).
Behavioral screening of the 103 dogs examined revealed resource guarding (61%) and
discipline measures (59%) as the most common stimuli for aggression.
Anxiety screens revealed abnormalities in 77% of dogs.
Potential contributory medical conditions were identified/suspected in 50% of dogs.
When history before presentation was known, 66% of dogs had never previously bitten a
child, and 19% had never bitten any human.
Most dogs (93%) were neutered, and 66% of owners had taken their dogs to obedience
training classes.
The researchers determined that most children were bitten by dogs with no history of biting
children. There was a high rate of behavioral abnormalities (aggression and anxiety) in this
canine population. Common calming measures (neutering, training) were not routinely effective
deterrents. The fact is that dog bite injuries are a complex problem that defies easy answers.
A second example of misrepresentation is found in the following statement: "Neutering male
dogs and cats...reduces the risk of prostatic disease...and infection." Although rates of benign
prostatic disease and infection may be lower in neutered dogs, the risk of prostatic cancer is
actually greater. Furthermore, there are some indications that early-age spay or neuter may
increase the risk of bone cancer in large-breed dogs. With regard to creating a healthier pet,
there are both positive and negative affects accrued from sterilization. On balance, it appears
that benefits outweigh risks (particularly when you look at the percentages associated with the
various negatives); however, there are many breed and individual dog variations, suggesting
that professional judgment is required to determine whether and when to spay/neuter pets. The
concept for mandatory spay/neuter originated with feral dogs and cats that were being managed
in colonies, and not euthanized when captured. These animals were not owned by anyone and
the goal was to prevent a population explosion. Feral animals do not have the life expectancy of
owned pets, therefore the negative health impacts of spay/neuter may be minimized or
unrealized. This concept does not and should not be extrapolated to apply to owned pets that
are members of families. Their medical decisions should rest with their owners who are
educated by their veterinarians as to when these procedures should be performed with minimum
risk and maximum benefit for their pet.
It's possible to identify both successes and failures in population control and euthanasia
reduction when it comes to mandatory spay/neuter. In general confounding factors make
interpretation of euthanasia statistics (when these are even available) extremely difficult and
drawing reliable conclusions almost impossible. Proponents of mandatory spay/neuter
proposals neglect to mention these factors when promoting their cause.
There are also practical issues associated with this ordinance. There simply are not enough
resources in Chicago to enforce this law in a meaningful way. Responsible, properly educated
people are already having their pets sterilized when medically prudent. It will have no effect on
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gangbangers’ compliance which is a major thrust of this legislation. It seems inappropriate that
a police officer’s time would be devoted to inspecting female dogs for spay scars and checking
male dogs for testicles when much more serious offenses are being perpetrated.
The unintended consequences of this proposal are of concern as well. Currently, we struggle to
ensure that proper safeguards are in place to protect the public from rabies. Rabies is
essentially a 100% fatal disease for humans and dogs. This mandatory law will discourage pet
owners from seeking immunization if they are opposed to spaying/neutering and fear they will be
reported for not having these surgeries performed. These procedures are not routinely
accepted by many cultures and only through contact with veterinarians and education can the
perspectives of individuals from such cultures be changed. We are convinced this law will result
in a decrease in vaccinations against rabies and owners seeking medical attention for their
pets.
You do not hear an overwhelming call for mandatory spay/neuter laws from animal health
professionals because many of the proposed benefits simply cannot be substantiated.
Mandatory spay/neuter laws have had a mixed result in reducing the number of unwanted pets,
placed an undue and unenforceable burden on police and animal control officials, reduced
vaccination compliance for rabies, and unintentionally restricted access to healthcare for pets.
The idea that mandatory spay/neuter will change a gangbanger’s behavior or that dog bite
injuries will vanish is absurd. At the end of the day, no progress will be made on gang behavior
or pet overpopulation and honest tax payers will be forced to give up yet another right in making
health decisions for their pets. This ordinance may seem like a quick-fix for aldermen seeking
solutions to challenging problems, but the reality is that it wi ll not fix the problems they are
looking to resolve. This ordinance will, however, create a nightmare for those who have to abide
by it--veterinarians, police officers, animal control officials, public health providers and honest
law-abiding taxpayers. Laws should be designed to solve problems, not create more. The
Illinois State Veterinary Medical Association recommends that this proposal be allowed to die
and welcomes a chance to help the city and citizens of Chicago and Illinois craft well written,
meaningful and thoughtful animal legislation.
Board of Directors
Illinois State Veterinary Medical Association
Early Spay and Neuter and the Canine Athlete
Early Spay Neuter and Incontinence
Early Spay Neuter and Behavior
Actually this is not the case. Canine Companions for Independence is the only organization that we are aware of that that has done side by side research on this issue. CCI would like to alter dogs at a very early age so they would be less work for puppy raisers. But in their research, with dogs from the same litter, early altered dogs had behavior problems that kept them for being viable service dogs for CCI.
It is really only common sense that all the endocrine glands are there for reasons. Dogs that are not allowed to mature into steady, reliable examples of their breed may have life long problems. And dogs with behavior problems end up in shelters. You'll find this fascinating.
Behavior
Growth, Hip Dysplasia, Immunology and Tumors
Orthapedic Considerations
In a 15-month study, the effects of prepubertal gonadectomy on skeletal growth, weight gain, food intake, body fat, secondary sex characteristics, and behavioral development were investigated in 32 mixed-breed dogs. Male and female pups from 5 litters were randomly allotted to 3 groups: group I, neuter at 7 weeks (n = 14); group II, neuter at 7 months (n = 8); and group III, sexually intact dogs (n = 10). Growth plate closure was delayed (group I vs group III; P less than 0.000001; group II vs group III, P less than 0.000001) in all neutered dogs, as compared with sexually intact dogs. Growth plate closure was delayed longer (group I vs group II, P less than 0.000045) in dogs neutered at 7 weeks old, compared with dogs neutered at 7 months old. The rate of growth was unaffected by gonadectomy, but the extended growth period resulted in greater final radial/ulnar length in all male dogs and bitches neutered at 7 weeks. Gonadectomy did not influence food intake, weight gain, or back-fat depth. Penile development was immature in the adult group-I males (mean +/- SEM diameter of pars glandis = 11.1 +/- 1.0 mm), compared with adult group-II (16.3 +/- 0.5 mm) andgroup-III (21.0 +/- 2.2 mm) males. Subjectively, the prepuce and os penis of the group-I males were immature, compared with those of group-II and group-III males. Vulvar development in group-I and group-II bitches was less mature than vulvar development in the sexually intact bitches. Of 7 behavioral characteristics assessed, only general activity and excitability rated differently among treatment groups. All neutered dogs were judged to be more active (group I, P less than 0.004) than sexually intact dogs. Group-I males were judged to be more excitable (P less than 0.02) than group-III males. It was concluded that with respect to skeletal, physical, and behavioral development, the effect of neutering pups at 7 weeks old was similar to that of neutering pups at 7 months old.
Am J Vet Res. 2005; 66(2):307-12 (ISSN: 0002-9645)
Incidence, risk factors, and heritability estimates of hind limb lameness caused by hip dysplasia in a birth cohort of boxers. van Hagen MA ; Ducro BJ ; van den Broek J ; Knol BW, Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80154, 3508 TD Utrecht, The Netherlands.
OBJECTIVE: To determine incidence, risk factors, and heritability estimates of hind limb lameness caused by hip dysplasia in a birth cohort of Boxers.
ANIMALS: 1733 Boxers from 325 litters.
PROCEDURE: Status of Boxers with respect to clinical signs of canine hip dysplasia (cCHD) was registered during an 8-year period. Survival analysis accounted for dogs lost to follow-up. Effective heritability for developing cCHD was estimated by use of a proportional hazard model on the basis of the Weibull distribution. Parametric survival models were developed to identify the influence of potential risk factors. RESULTS: Cumulative hazard rate for cCHD from 7 weeks to 8 years of age was 8.5%. Dogs that were kept on a floor covered with a slippery material were 1.6 times as likely to develop cCHD, compared with dogs kept on a nonslippery floor. Risk of cCHD doubled in dogs from litters with a high preweaning mortality rate. Dogs that were neutered at 6 months prior to a diagnosis of CHD were 1.5 times as likely to develop cCHD, compared with sexually intact dogs. Dogs >5 years of age were 1.8 times as likely to develop cCHD, compared with younger dogs. Estimated effective heritability of cCHD was 0.11. In terms of the risk of cCHD in progeny, mean estimated breeding value (EBV) of the 10 best and 10 worst sires was -0.32 and 0.42, respectively.
CONCLUSIONS AND CLINICAL RELEVANCE: Registration of Boxers that develop cCHD may provide a strategy for disease prevention. In addition to diagnostic evaluation of radiographs, sire EBVs provide useful information for breeding selection decisions.
J Am Vet Med Assoc. 1993; 203(7):1016-9 (ISSN: 0003-1488) Epidemiology of cranial cruciate ligament rupture in dogs. Whitehair JG; Vasseur PB; Willits NH, Veterinary Medical Teaching Hospital, Department of Surgery, School of Veterinary Medicine, University of California, Davis 95616.
Data from 10,769 dogs with rupture of the cranial cruciate ligament (CCL) were compared with data from a control population of 591,548 dogs to determine whether age, breed, gender, or body weight was associated with prevalence of CCL rupture. Prevalence of CCL rupture increased as dogs became older, with peak prevalence in dogs 7 to 10 years old. Among breeds represented by > 1,000 individuals, Rottweilers, Newfoundlands, and Staffordshire Terriers had the highest prevalence of CCL rupture, whereas Dachshunds, Basset Hounds, and Old English Sheepdogs had the lowest. Neutered dogs, whether male or female, had a higher prevalence of CCL rupture than did sexually intact dogs. The dog's age at the time of ovariohysterectomy was not associated with prevalence of CCL rupture. Dogs weighing > 22 kg had a higher prevalence of CCL rupture, compared with dogs weighing < 22 kg, and tended to rupture their CCL at a younger age.
Calcif Tissue Int. 1998; 62(3):237-43 (ISSN: 0171-967X) Ovariectomy-induced changes in aged beagles: histomorphometry of rib cortical bone. WilsonAK ;Bhattacharyya MH; Miller S ;Mani A; Sacco-Gibson N, Center for Mechanistic Biology and Biotechnology, Argonne National Laboratory, Illinois 60439, USA.
Bone loss associated with estrogen depletion is well documented in cancellous bone but less well characterized in cortical bone. The effects of ovariectomy on the aged beagle skeleton were studied by histomorphometric analysis of the cortical bone in sequential rib biopsies. Biopsies were taken from each ovariectomized or sham-operated dog at the time of surgery and at 1, 4, and 8.5 months after surgery. Just prior to each postoperative biopsy, tetracycline, calcein, and xylenol orange, respectively, were administered by a fluorochrome labeling procedure (2d-10d-2d) to provide markers of bone formation. Analysis of sequential rib biopsies provided a means to follow the ovariectomy response over time and to compare each animal against its own baseline. Though ovariectomy did not influence histomorphometric indices at 1 month after surgery, a transient increase in cortical bone formation occurred thereafter, with a sixfold increase over that of sham-operated dogs at 4 months (P < 0.001) and a return to near control levels at 8.5 months. Cortical porosity increased by the fourth month after ovariectomy and remained high at 8.5 months. These data demonstrate for the first time that rib cortical bone is a responsive site for the effects of ovariectomy in aged female dogs.
J Am Vet Med Assoc, 203(7): 1016-9 1993
Epidemiology of cranial cruciate ligament rupture in dogs.
Whitehair JG , Vasseur PB , Willits NH
Data from 10,769 dogs with rupture of the cranial cruciate ligament (CCL) were compared with data from a control population of 591,548 dogs to determine whether age, breed, gender, or body weight was associated with prevalence of CCL rupture. Prevalence of CCL rupture increased as dogs became older, with peak prevalence in dogs 7 to 10 years old. Among breeds represented by > 1,000 individuals, Rottweilers, Newfoundlands, and Staffordshire Terriers had the highest prevalence of CCL rupture, whereas Dachshunds, Basset Hounds, and Old English Sheepdogs had the lowest. Neutered dogs, whether male or female, had a higher prevalence of CCL rupture than did sexually intact dogs. The dog's age at the time of ovariohysterectomy was not associated with prevalence of CCL rupture. Dogs weighing > 22 kg had a higher prevalence of CCL rupture, compared with dogs weighing < 22 kg, and tended to rupture their CCL at a younger age.
Cancer Considerations
A case-control study using the Veterinary Medical Data Base (VMDB) was conducted to test the hypothesis that increasing height and increasing weight are important risk factors for osteosarcoma in dogs. The role of other host factors was also explored. The cases comprised 3062 purebred dogs with histologically or radiographically confirmed osteosarcoma admitted to 24 veterinary teaching hospitals in the United States and Canada between 1980 and 1994. The controls were 3959 purebred dogs with other diagnoses obtained randomly by frequency matching to cases for institution and year of diagnosis. The risk of osteosarcoma rose with increasing age, increasing body weight, increasing standard weight and increasing standard height. Compared with the German Shepherd breed, the highest risk of osteosarcomas was found for large and giant breeds, while small breeds had reduced risks. A twofold excess risk was observed among neutered dogs. Adjustment of risk estimates for standard height adjusted for standard weight, and vice versa, showed a stronger and more consistent association of osteosarcoma with increasing height than increasing weight.
Cancer Epidemiol Biomarkers Prev. 2002 Nov;11(11):1434-40.
Endogenous gonadal hormone exposure and bone sarcoma risk.
Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters DJ., Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
Although experimental and clinical evidence suggest that endogenous sex hormones influence bone sarcoma genesis, the hypothesis has not been adequately tested in an appropriate animal model. We conducted a historical cohort study of Rottweiler dogs because they frequently undergo elective gonadectomy and spontaneously develop appendicular bone sarcomas, which mimic the biological behavior of the steosarcomas that affect children and adolescents. Data were collected by questionnaire from owners of 683 Rottweiler dogs living in North America. To determine whether there was an association between endogenous sex hormones and risk of bone sarcoma, relative risk (RR) of incidence rates and hazard ratios for bone sarcoma were calculated for dogs subdivided on the basis of lifetime gonadal hormone exposure. Bone sarcoma was diagnosed in 12.6% of dogs in this cohort during 71,004 dog-months follow-up. Risk for bone sarcoma was significantly influenced by age at gonadectomy. Male and female dogs that underwent gonadectomy before 1 year of age had an approximate one in four lifetime risk for bone sarcoma and were significantly more likely to develop bone sarcoma than dogs that were sexually intact [RR +/-95% CI = 3.8 (1.5-9.2) for males; RR +/-95% CI = 3.1 (1.1-8.3) for females]. Chi(2) test for trend showed a highly significant inverse dose-response relationship between duration of lifetime gonadal exposure and incidence rate of bone sarcoma (P = 0.008 for males, P = 0.006 for females). This association was independent of adult height or body weight. We conclude that the subset of Rottweiler dogs that undergo early gonadectomy represent a unique, highly accessible target population to further study the gene:environment interactions that determine bone sarcoma risk and to test whether interventions can inhibit the spontaneous development of bone sarcoma
Vet Intern Med 1987 Oct-Dec;1(4):183-7 Related Articles, Books
The influence of castration on the development of prostatic carcinoma in the dog: 43 cases (1978-1985) Obradovich J, Walshaw R, Goullaud E Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824.
Prostatic carcinoma (PC) was diagnosed in 43 dogs at the Michigan State University Veterinary Clinical Center (MSU-VCC) between 1978 and 1985. Of the 43 dogs with histologically confirmed PC, 19 (44.19%) had been castrated at least three years prior to the development of any prostatic disease. Seven of the castrates had been neutered at less than 12 months of age. Fourteen dogs (32.55%) were presented as intact males at the time of diagnosis. The remaining ten dogs (23.62%) had been castrated as treatment for presumptive prostatic disease prior to referral to the MSU-VCC. Dates of castration were known in all cases. In this study, therefore, castration at any age showed no sparing effect on the risk of development of PC in the dog. The etiology of PC in the dog may not be exclusively related to testicular hormones. Work in humans suggests that the adrenal and pituitary glands play a significant role in the disease. Preliminary work in dogs supports that nontesticular androgens exert a significant influence on the canine prostate.
Acta Anat (Basel) 1984;120(3):103-7 Related Articles, Books
Early changes in the dog prostate after castration. An ultrastructural study. Sinowatz F
Using electron microscopic techniques the prostate glands of male Beagle dogs were studied 3 days after castration. At this time marked differences in the extent of alterations of the glandular epithelium were observed: Whereas several acini showed only minor changes with reduction of epithelial height and diminution of secretory granules, many acini were severely affected with pronounced alteration of cellular structure and accumulation of large lipid droplets. A constant feature was the stimulation of the basal cells of the grandular epithelium. Additionally, in some areas of the gland aggregations of stimulated basal cells forming an acinus-like structure with a slit-like lumen were found. Our study shows that castration leads to marked alterations of prostatic epithelium within a short time. Androgen deprivation causes regressive changes of secretory epithelial cells, but clearly stimulates the basal cell population.
J Vet Intern Med 1999 Mar-Apr;13(2):95-103
Cardiac tumors in dogs: 1982-1995. Ware WA, Hopper DL.
A Veterinary Medical Database search from 1982 to 1995 identified 1,383 dogs with tumors of the heart from a total population of 729,265 dogs (0.19% incidence). Hemangiosarcoma (HSA) was the most common cardiac tumor identified. In the subset of dogs with specific histologic diagnoses, the number with HSA was almost 10-fold that of the 2nd most common tumor, aortic body tumor. Primary heart tumors were more common than cardiac metastases. When biologic behavior was noted, most heart tumors were classified as malignant. Cardiac tumors (excluding lymphoma) occurred most often in dogs between the ages of 7 and 15 years. In very old dogs (>15 years), the frequency of cardiac tumors was the same or lower than that of the youngest age group. Tumors occurred with similar frequency in males and females, but the relative risk for spayed females was >4 times that for intact females. For HSA, spayed females had >5 times greater relative risk than did intact females. The risk for castrated males was slightly greater than that for intact males, which had 2.4 times the relative risk of intact females. Thus, neutering appeared to increase the risk of cardiac tumor in both sexes. Intact females were least likely to develop a cardiac tumor, whereas spayed females were most likely to develop a tumor. Twelve breeds had greater than average risk of developing a cardiac tumor, whereas 17 had lower risk.
Source: J Vet Intern Med, 6(3): 145-53 1992
Canine bladder and urethral tumors: a retrospective study of 115 cases (1980-1985).
Norris AM , Laing EJ , Valli VE , Withrow SJ , Macy DW , Ogilvie GK , Tomlinson J , McCaw D , Pidgeon G , Jacobs RM
One hundred and fifteen dogs with neoplasms of the lower urinary tract (bladder and/or urethra) were retrospectively evaluated at five referral institutions participating in ongoing studies by the Veterinary Cooperative Oncology Group. Most tumors were malignant (97%) and of epithelial origin (97%). Lower urinary tract tumors were more common in older dogs weighing greater than 10 kg. The following significant (P less than 0.05) statistical associations were found using the University of Guelph hospital population as control; there was no sex predisposition although the female:male ratio was 1.95:1. Neutered dogs were predisposed as were Airedale Terriers, Beagles, and Scottish Terriers, whereas German Shepherds were significantly under-represented among dogs with lower urinary tract tumors. These statistical associations should be interpreted cautiously because of possible demographic differences in hospital populations among the University of Guelph and other cooperating institutions. There were no significant correlations between age, gender, weight, breed, response to therapy, and survival time. Clinical signs were indicative of lower urinary tract disease and included hematuria, stranguria, and pollakiuria. The laboratory data were nonspecific except for urinalysis test results. Hematuria and inflammatory urinary sediments were most commonly reported; neoplastic cells were identified in the urine sediment of 30% of dogs with lower urinary tract tumors. Contrast cystography was a useful noninvasive diagnostic method since 96% of the dogs had a mass or filling defect in the lower urinary tract demonstrated by this technique.
J Am Vet Med Assoc, 200(8): 1119-22 1992
Study of prostatic disease in dogs: 177 cases (1981-1986).
Krawiec DR , Heflin D
Historical and physical signs associated with prostatic disease diagnosed in dogs over a 5.5-year period were defined. One hundred seventy-seven male dogs were determined to have prostatic abnormality. Of the 177 dogs, 87 were determined to have specific prostatic disease. The most common prostatic disease identified in this study was bacterial prostatitis, followed by prostatic cyst, prostatic adenocarcinoma, and benign hyperplasia. The most common prostatic disease identified in neutered dogs was prostatic adenocarcinoma. Mean age at onset of prostatic disease was 8.9 years; statistically significant difference was not observed between age at onset of the various types of prostatic disease identified. Doberman Pinscher was the most common breed with prostate disease. Twenty-nine percent of dogs with a specifically identifiable prostatic disease had signs of systemic illness, 41% had signs of lower urinary tract disease, 28% had signs of gastrointestinal tract abnormalities, and 13% had signs of locomotor difficulty.
Incontinence Considerations
Abstract:It is still controversial whether a bitch should be spayed before or after the first oestrus. It would be desirable to spay bitches at an age that would minimize the side effects of neutering. With regard to the risk of mammary tumours, early spaying must be recommended because the incidence of tumours is reduced considerably. The aim of the present study was to determine whether early spaying also reduces the risk of urinary incontinence. The owners of 206 bitches that had been spayed before their first oestrus and for at least 3 years were questioned on the occurrence of urinary incontinence as a result of spaying. At the time of the enquiry the average age of the bitches was 6.5 years, and the average age at the time of surgery was 7.1 months. Urinary incontinence after spaying occurred in 9.7% of bitches. This incidence is approximately half that of spaying after the first oestrus. Urinary incontinence affected 12.5% of bitches that were of a large body weight (> 20 kg body weight) and 5.1% of bitches that were of a small body weight (< 20 kg body weight). The surgical procedure (ovariectomy versus variohysterectomy) had no influence on the incidence, or on the period between spaying and the occurrence of urinary incontinence. Urinary incontinence occurred on average at 2 years and 10 months after surgery and occurred each day, while the animals were awake or during sleep. However, compared with late spaying the clinical signs of urinary incontinence were more distinct after early spaying.
Schweiz Arch Tierheilkd. 1997; 139(6):271-6 (ISSN: 0036-7281)
Urinary incontinence in castrated bitches. Part 1: Significance, clinical aspects and etiopathogenesis Arnold S Arnold P ; Hubler M ; Casal M ; Rüsch P, Departement für Fortpflanzungskunde, Veterinär-Medizinische Fakultät, Universität Zürich.
Acquired urinary incontinence occurs in 20% of spayed dogs and there exists a strong correlation between body weight and the risk of urinary incontinence. Bitches with a body weight of more than 20 kg have a risk of 30% white smaller dogs have a risk of 10%. A particular breed disposition exists in Boxers in which 65% are affected. Other breeds with a more than average disposition for urinary incontinence are Dobermans and Giant Schnauzers. Urinary incontinence due to spaying manifests itself mainly while the dogs are sleeping. The cause is a urethral sphincter incompetence which can be verified by a urethral pressure profile (UPP). The microtransducer method proved to be a suitable method for urodynamic studies. It could be demonstrated that the urethral closure pressure is significantly lower in incontinent bitches (4.6 +/- 2.3 cm H2O) than in continent bitches (18.6 +/- 10.5 cm H2O). In addition, the urethral closure pressure for continent bitches dropped significantly within 12 months after surgery. Histological examination revealed that the functional urethral closure cannot be explained by the extent of discernible structures of the urethral wall as seen by light microscopy.
Schweiz Arch Tierheilkd. 1989; 131(5):259-63 (ISSN: 0036-7281) Urinary incontinence in spayed female dogs: frequency and breed disposition. Arnold S ; Arnold P ; Hubler M ; Casal M ; Rüsch P
A follow up study was performed in 412 spayed bitches in order to determine the incidence of urinary incontinence. The period between the operation being performed and the survey being made varied between 3 and 10 years. 83 animals (20.1%) were incontinent independent of the surgical procedure (ovariectomy versus ovariohysterectomy). The onset of incontinence varied between immediately to 12 years with an average period of 2.9 years after surgery. 57 of these incontinent bitches were treated with ephedrine or estrogen. In 73.7% a good response was achieved with ephedrine and a further 23.7% showed some improvement. Generally ephedrine was more successful than estrogen in the treatment of incontinence. There appears to be a strong connection between body weight and the incidence of incontinence. Of bitches with a body weight of less than 20 kg only 9.3% were incontinent. Whereas in bitches with a body weight of more than 20 kg the incidence was 30.9%. Of the breeds Boxers showed a high incidence of incontinence (65%) while breeds such as German Shepherds (10.6%) or Dachshunds (11.1%) showed a low incidence in relation to the average incidence rate (20.1%).
Vet Rec. 1997; 141(24):620-5 (ISSN: 0042-4900)
Comparisons between stress incontinence in women and sphincter mechanism incompetence in the female dog. Janssens LA ; Peeters S
University of Antwerp, Laboratory of Medical Electronics, Belgium.
In dogs, sphincter mechanism incompetence most often affects middle-aged spayed bitches and is more prevalent in docked animals, certain breeds and in dogs over 30 kg in weight. It results in urinary leakage, mainly when the animal is recumbent and relaxed. In humans, stress incontinence occurs most often in post-menopausal women who are multiparous, have had difficult deliveries and are obese. They also leak urine, but most often when active stressors increase abdominal pressure. Both women and bitches have shorter functional urethras and lower maximal urethral pressures. In women, the compliance and cross-sectional area of the urethra are increased and power generation is substantially weakened. Many women and most bitches have an intrapelvic bladder neck and a short urethra. Owing to hormonal deficiencies they have an impaired capacity to seal the lumen of the urethra and the urethral sphincter is less sensitive to sympathomimetics. In women partial denervation of the pudendal nerve is also a contributory factor.
PRESENTATION SUMMARY & POWERPOINT
Incontinence in Spayed Bitches: Frequency, Causes & Therapy
Iris Reichler, Madeleine Hubler and Susi Arnold, Vetsuisse-Faculty, University of Zurich, Switzerland
Urinary incontinence (UI) is the involuntary loss of urine. UI rarely occurs in sexually intact bitches (0-1%)1, whereas in spayed bitches the incidence is up to 20%2, The underlying pathophysiological mechanism is a reduced closure pressure of the urethra after spaying3.
The causal relationship between the removal of the ovaries and UI has been clearly demonstrated4, However, it is still unclear what mechanism triggers UI after spaying. An oestrogen deficiency was initially considered to be the underlying cause5, This hypothesis is however contradicted by several observations. For example, bitches treated with depot preparations of gestagens, to suppress oestrus, do not have an increased risk of UI, even though the treatment results in ovarian atrophy6, and the oestrogen remains in a basal level7, Another side effect of spaying is the increase in plasma gonadotropins, due to the lack of the ovarian negative feedback8, About 42 weeks after ovarectomy the gonadotropin levels reach a plateau, when the plasma FSH is 17 times and the plasma LH is 8 times the initial concentration9, One could therefore ask if it is the elevated plasma level of FSH and LH that are responsible for the increased risk of UI in spayed bitches. If this were correct, then affected bitches could be successfully treated with depot preparations of GnRHanalogues, through down-regulation of GnRH-receptors in the pituitary and this in turn will decrease the plasma gonadotropin concentrations. Indeed, 7 of 13 bitches affected by UI were successfully treated with an injection of depot preparations of GnRH-analogues and remained continent for an average of 247 days10, However, it is questionable whether the success of this treatment is due to a decrease in gonadotropins since their blood levels in responders and non-responders are not different11, It is possible that GnRH has a directeffect on the lower urinary tract, but the success of the therapy is not based on a normalisation of the urethral sphincter incompetence after spaying11, Recent studies in beagle bitches have given rise to the assumption that GnRH modulates the function of the bladder12, The treatment of incontinent bitches with GnRH-analogues is mainly interesting for the clarification of the pathophysiological mechanism. For patients affected by UI, the therapy of first choice is with alpha-adrenergica (Phenylpropanolamine / Ephedrine). This results in an increased urethral closure pressure and continence in more than 90% of cases. If the therapeutic effect is insufficient, then alpha-adrenergica may be combined with oestrogen or Flavoxatum. In refractory cases, several surgical methods are described ofwhich colposuspension13, urethropexy14, and the endoscopic injection of collagen15, aremost common and have a success rate of 50 - 75%.
References 1. Thrusfield, Holt and Muirhead (1998) J Small Anim Pract 39:559-566. 2. Arnold et al. (1989) Schweiz Arch Tierheilk 131:259-263. 3. Rosin and Barsanti (1981) JAVMA 178:814-822. 4. Thrusfield (1985) Vet Rec 116:695. 5. Finco, Osborne and Lewis (1974) Vet Clin North Am 4:501-516. 6. El Etreby (1979) Cell Tissue Res 200:229-243. 7. De Bosschere et al. (2002) Theriogenology 58:1209-1217. 8. Olson, Mulnix and Nett (1992) Am J Vet Res 53:762-766. 9. Reichler et al. (2004) Theriogenology 62:1391-1402. 10. Reichler et al. (2003) Theriogenology 60:1207-1216. 11. Reichler et al., Theriogenology, in press (2006). 12. Reichler et al., Theriogenology, in press (2006). 13. Holt, J Small Anim Pract 26:237-246, 1985. 14. White, J Small Anim Pract, 42: 481-486, 2001. 15. Arnold et el. (1996) Small Anim Pract 37:163-168.
Behavioral Considerations
OBJECTIVE: To determine whether gonadectomy predisposes dogs to development of age-related behavioral changes linked to cognitive impairment. DESIGN: Cohort study. ANIMALS: 29 sexually intact male dogs, 63 spayed female dogs, and 47 castrated male dogs 11 to 14 years old.
PROCEDURE: Information on possible impairments in 4 behavioral categories linked to cognitive impairment (orientation in the home and yard, social interactions, house training, and sleep-wake cycle) was obtained from owners of the dogs by use of a structured telephone interview format. A second interview was performed 12 to 18 months after the initial interview, and differences in responses were evaluated.
RESULTS: Sexually intact male dogs were significantly less likely than neutered dogs to progress from mild impairment (i.e., impairment in 1 category) to severe impairment (i.e., impairment in > or = 2 categories) during the time between the first and second interviews. This difference was not attributable to differences in ages of the dogs, duration of follow-up, or the owners' perceptions of the dogs' overall health.
CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the presence of circulating testosterone in aging sexually intact male dogs may slow the progression of cognitive impairment, at least among dogs that already have signs of mild impairment. Estrogens would be expected to have a similar protective role in sexually intact female dogs; unfortunately, too few sexually intact female dogs were available for inclusion in the study to test this hypothesis. There may be a need to evaluate possible methods for counteracting the effects of loss of sex hormones in gonadectomized dogs.
PRESENTATION SUMMARY POWERPOINT
Non-reproductive Effects of Spaying and Neutering on Behavior in Dogs. Deborah L. Duffy, Ph.D., and James A. Serpell, Ph.D., Center for the Interaction of Animals and Society, School of Veterinary Medicine, University of Pennsylvania
Although there are scattered reports in the literature of apparently adverse effects of spaying and neutering on canine behavior, there are very few quantitative studies and most of these have employed behavioral measures of unknown reliability and validity. The present study used the Canine Behavioral Assessment and Research Questionnaire(C-BARQ) to investigate the impact of spaying/neutering in various dog populations, including (1) a random sample of 1,552 dogs belonging to 11 common breeds and (2) a convenience sample of over 6,000 dogs of various breeds recruited via an online survey. The C-BARQ is a reliable, standardized method for evaluating and screening dogs for the presence and severity of behavioral problems. It was developed by behavioral researchers at the University of Pennsylvania (Hsu and Serpell, 2003) and consists of a 101-item questionnaire that is simple to use, takes about 15 minutes to fill out, and can be completed by anyone who is reasonably familiar with the dog’s typical responses to ordinary, day-to-day events and stimuli. The C-BARQ is currently the only existing behavioral assessment instrument of its kind to be thoroughly tested for reliability and validity on large samples of dogs of various breeds. This process has resulted in the identification of the following 13 distinct behavioral factors or traits that are common to the majority of dogs, regardless of breed, age, sex or neuter status: 1. Stranger-directed aggression: Dog shows threatening or aggressive responses to strangers approaching or invading the dog’s or the owner’s personal space, territory, or home range. 2. Owner-directed aggression: Dog shows threatening or aggressive responses to the owner or other members of the household when challenged, manhandled, stared at, stepped over, or when approached while in possession of food or objects. 3. Dog-directed fear/aggression: Dog shows fearful and/or aggressive responses when approached directly by unfamiliar dogs. 4. Familiar dog aggression: Threatening or aggressive responses during competition for resources with other (familiar) dog(s) in the household. 5. Stranger-directed fear: Fearful or wary responses when approached directly by strangers. 6. Nonsocial fear: Fearful or wary responses to sudden or loud noises, traffic, and unfamiliar objects and situations. 7. Separation-related behavior: Vocalizes and/or engages in destructive behavior when separated from the owner, often accompanied or preceded by behavioral and autonomic signs of anxiety, including restlessness, loss of appetite, trembling, and excessive salivation. 8. Attachment and attention-seeking: Maintains close proximity to the owner or other members of the household, solicits affection or attention, and becomes agitated when the owner gives attention to third parties. 9. Trainability: Shows willingness to attend to the owner, obeys simple commands, fetches objects, responds positively to correction, and ignores distracting stimuli. 10. Chasing: Pursues cats, birds, and other small animals, given the opportunity. 11. Excitability: Strong reaction to potentially exciting or arousing events, such as going for walks or car trips, doorbells, arrival of visitors, and the owner arriving home; difficulty settling down after such events. 12. Touch sensitivity: Fearful or wary responses to potentially painful procedures,including bathing, grooming, claw-clipping, and veterinary examinations.
13. Energy level: Highly energetic, boisterous, and/or playful behavior. The results of the study suggest that spayed female dogs tend to be more aggressive toward their owners and to strangers than intact females, but that these effects of spaying on behavior appear to be highly breed-specific. Contrary to popular belief, the study found little evidence that castration was an effective treatment for aggressive behavior in male dogs, and may exacerbate other behavioral problems. Further research will be needed to clarify the relationship between age of spaying/neutering and these apparent effects on behavior.
J Am Vet Med Assoc. 2004 Feb 1;224(3):372-9.
Long-term risks and benefits of early-age gonadectomy in cats. Spain CV, Scarlett JM, Houpt KA. Department of Population Medicine and Diagnostic Science, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
OBJECTIVE: To evaluate the long-term risks and benefits of early-age gonadectomy, compared with traditional-age gonadectomy, among cats adopted from a large animal shelter. DESIGN: Retrospective cohort study.
ANIMALS: 1,660 cats.
PROCEDURE: Cats underwent gonadectomy and were adopted from an animal shelter before 1 year of age; follow-up was available for as long as 11 years after surgery (median follow-up time, 3.9 years). Adopters completed a questionnaire about their cats' behavior and medical history. When possible, the cats' veterinary records were reviewed. Statistical analyses were conducted to identify any associations between the occurrence of 47 medical and behavioral conditions and the cats' age at gonadectomy.
RESULTS: Among male cats that underwent early-age gonadectomy (< 5.5 months of age), the occurrence of abscesses, aggression toward veterinarians, sexual behaviors, and urine spraying was decreased, whereas hiding was increased, compared with cats that underwent gonadectomy at an older age. Among male and female cats that underwent early-age gonadectomy, asthma, gingivitis, and hyperactivity were decreased, whereas shyness was increased.
CONCLUSIONS AND CLINICAL RELEVANCE: Gonadectomy before 5.5 months of age was not associated with increased rates of death or relinquishment or occurrence of any serious medical or behavioral condition and may provide certain important long-term benefits, especially for male cats. Animal shelters can safely gonadectomize cats at a young age, and veterinarians should consider recommending routine gonadectomy for client-owned cats before the traditional age of 6 to 8 months.
PMID: 14765796 [PubMed - indexed for MEDLINE]
Vet J. 2006 Jul;172(1):154-9.
Effects of ovariohysterectomy on reactivity in German Shepherd dogs.
Kim HH, Yeon SC, Houpt KA, Lee HC, Chang HH, Lee HJ. Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea.
This study investigated the effects of ovariohysterectomy on reactivity of German Shepherd dogs. Fourteen healthy dogs ranging in age from 5 to 10 months were assigned to an ovariohysterectomy or a sexually intact group. Their behaviours were digitally video recorded 4-5 months after treatment and analysed for treatment effects on reactivity. Responses to the approach of an unfamiliar human leading an unknown dog were assigned the following reactivity scores: severe reactivity, 3; moderate reactivity, 2; defensive or mild reactivity, 1; attentive or no reactivity, 0. Median reactivity scores in response to the approach of an unfamiliar human walking with an unknown dog were calculated for each observation[ct1] period. Dogs in the ovariohysterectomized group showed more reactivity, and median reactivity scores were higher in the ovariohysterectomy group compared with those of the sexually intact group. Ovariohysterectomy of 5-10 month old German Shepherd bitches specifically, and perhaps bitches of any breed generally, may induce an increase in reactivity. Practitioners may benefit from recognizing that a range of behavioural changes may occur post-ovariohysterectomy.
Metabolic Considerations
From the Merck Veterinary Manual 8th Edition Page 416 - The Thyroid Gland
Clinical Findings: Although onset is variable, hypothyroidism is most common in dogs 4-10 years old. It usually affects mid-to large-size breeds and is rare in toy and miniature breeds. Breeds reported to be predisposed include the Golden Retriever, Doberman Pinscher, Irish Setter, Miniature Schnauzer, Dachshund, Cocker Spaniel, and Airedale Terrier. There does not appear to be a sex predilection, but the risk of developing hypothyroidism appears to be higher in spayed females than in intact females.
Pancreatitis
J Am Vet Med Assoc, 214(1): 46-51 1999
Evaluation of risk factors for fatal acute pancreatitis in dogs.
Hess RS , Kass PH , Shofer FS , Van Winkle TJ , Washabau RJ
OBJECTIVE: To identify risk factors associated with fatal acute pancreatitis in dogs.
DESIGN: Case-control study. ANIMALS: 70 case dogs with clinical evidence and histopathologic confirmation of fatal acute pancreatitis and 104 control dogs that had trauma, underwent necropsy, and did not have histologic evidence of acute pancreatitis.
PROCEDURE: Information on signalment, weight, body condition, medical history, concurrent disease, and results of histopathologic examination was obtained by reviewing medical records. Logistic regression analysis included calculation of univariate and multivariate (adjusted) odds ratios and 95% confidence intervals.
RESULTS AND CLINICAL IMPLICATIONS: Dogs with fatal acute pancreatitis were largely middle- to older-aged dogs. Risk of developing fatal acute pancreatitis was increased by overweight body condition, diabetes mellitus, hyperadrenocorticism, hypothyroidism, prior gastrointestinal tract disease, and epilepsy. Additionally, Yorkshire Terriers were at increased risk, and Labrador Retrievers and Miniature Poodles were at decreased risk, of developing fatal acute pancreatitis. Males and neutered females appeared to have an increased risk of developing fatal acute pancreatitis, compared with sexually intact females. Thrombus formation was more likely in dogs that developed fatal acute pancreatitis than in control dogs.
Diabetes
Source: Am J Vet Res, 43(3): 465-70 1982
Epizootiologic patterns of diabetes mellitus in dogs.
Author: Marmor M , Willeberg P , Glickman LT , Priester WA , Cypess RH , Hurvitz AI
A case-control study of spontaneous diabetes mellitus in dogs was undertaken, using 2 veterinary data bases. The Veterinary Medical Data Program (VMDP) contained records of 1,019 cases of canine diabetes from 14 university-affiliated veterinary hospitals. The Animal Medical Center (AMC), a private veterinary hospital which has not participated in the VMDP, contained records of 449 diabetes cases. Each data base was analyzed separately, control groups being chosen from all admissions, excluding diabetic animals. Summary odds ratios by sex adjusted for age and breed indicated significantly (P less than 0.05) elevated risks for entire females and neutered females compared with that for entire males. The VMDP data indicated a significantly elevated risk for castrated males, whereas the risk derived from AMC data was not significantly different from 1. Analysis of risks by breed adjusting for age and sex identified Poodles as being at significantly excess risk, and German Shepherd Dogs, Cocker Spaniels, Collies, and Boxers at significantly decreased risk in both data sets. The male-female risk ratio changed with age from 1 at less than 1 year of age to a predominance of females at older ages. In the AMC data base, diabetes was significantly associated with cataracts in dogs of both sexes combined. Diabetes was also significantly associated with benign mammary tumors in female dogs.
Obesity
Source: J Anim Physiol Anim Nutr (Berl), 90(9-10): 355-60 2006
Hormonal disturbances associated with obesity in dogs.
Author: Martin LJ , Siliart B , Dumon HJ , Nguyen PG
Obesity is associated with multiple endocrine alterations and changes in the concentration of circulating hormones. However, few studies have explored such alterations in dogs with naturally acquired excess weight. In the present study, we investigated the effect of naturally acquired obesity on cortisol, insulin-like growth factor (IGF)-1 and prolactin secretion in dogs. Thirty-one overweight dogs were enrolled in the trial. Blood samples were collected before and after adrenocorticotrophic hormone (ACTH) injection. Free thyroxine (fT4), cortisol, thyroid-stimulating hormone (TSH), IGF-1, prolactin and fructosamine were assayed. Body weight excess increased significantly with age and neutered dogs were more obese than entire ones. The ACTH stimulation test was within the normal range for 26 of 31 dogs. Prolactinaemia was increased in seven dogs and IGF-1 in six dogs. Twenty dogs had a fructosamine concentration >340 microm. Interestingly, 18 of 31 dogs showed disturbances of thyroid function based on high TSH and/or low fT4 baseline concentration, with 11 dogs showing both. According to these parameters only six of 31 dogs were free of hormonal disturbances. These results revealed the high incidence of such disturbances, especially thyroid dysfunction, in obese, but otherwise apparently healthy dogs. They demonstrate the importance of examining endocrine function during the initial evaluation of obese dogs to avoid failure of any nutritional treatment.
Vet Rec, 118(14): 391-6 1986
Study of obesity in dogs visiting veterinary practices in the United Kingdom. Edney AT , Smith PM
A total of 8268 dogs were surveyed in 11 veterinary practices in the United Kingdom during a period of six months in 1983. The primary purpose of the survey was to assess the level of obesity on a five point scale with properly identified criteria. Information on the clinical condition of each dog was also recorded as well as proportions of food types fed, particulars of breed, sex, age, sexual status and the dog's name. Results showed that 21.4 per cent of dogs in the survey were judged to be obese and 2.9 per cent gross; 1.9 per cent were judged as thin, 13.5 per cent lean and 60.3 per cent were optimum. Labradors were found to be the most likely breed to become obese. Neutered females were about twice as likely to be obese as entire females. The same trend was evident with neutered males. Circulatory problems were associated with dogs over 10 years old and those which were gross, rather than obese. A similar trend was discernable with articular/locomotor problems. Skin and reproductive problems showed little relationship with age or obesity. Neoplasia was much more prevalent in dogs over 10 years old but had little relationship with either sexual status or obesity rating. There was a high rate of usage of prepared food for all categories. The amount of fresh food fed decreased rapidly as the proportion of canned food increased, but the obese and non-obese dogs showed very little difference in the type of food fed.
Infectious Disease Considerations
OBJECTIVE: To determine long-term results and complications of gonadectomy performed at an early age (prepubertal) or at the traditional age in dogs.
DESIGN: Cohort study.
ANIMALS: 269 dogs from animal shelters.
PROCEDURE: Dogs that underwent gonadectomy were allotted to 2 groups on the basis of estimated age at surgery (traditional age, > or =24 weeks old; prepubertal, < 24 weeks old). Adoptive owner information was obtained from shelter records, and telephone interviews were conducted with owners to determine physical or behavioral problems observed in the dogs since adoption. Follow-up information was obtained from attending veterinarians for dogs with complex problems or when owners were uncertain regarding the exact nature of their dog's problem.
RESULTS: Prepubertal gonadectomy did not result in an increased incidence of behavioral problems or problems associated with any body system, compared with traditional-age gonadectomy, during a median follow-up period of 48 months after gonadectomy. Rate of retention in the original adoptive household was the same for dogs that underwent prepubertal gonadectomy as those that underwent traditional-age gonadectomy. Infectious diseases, however, were more common in dogs that underwent prepubertal gonadectomy.
CONCLUSIONS AND CLINICAL IMPLICATIONS: With the exception of infectious diseases, prepubertal gonadectomy may be safely performed in dogs without concern for increased incidence of physical or behavioral problems during at least a 4-year period after gonadectomy.
Surgical Considerations
Postoperative complications (POC) that developed in dogs and cats that underwent elective ovariohysterectomy, castration, and declaw at a veterinary teaching hospital were determined by examining the computerized abstracts of the medical records and by examining a random sample of the paper medical records. When the computerized abstracts were examined, POC were found to have occurred in 62 (6.1%) of 1,016 dogs. One dog died and 6 others developed major complications. Postoperative complications were found to have occurred in 38 (2.6%) of 1,459 cats. Two cats died and 1 was euthanatized. Four other cats developed major complications. Complete paper medical records for 218 dogs and cats were examined. When the paper medical records were examined, the proportions of dogs and cats with POC were 19.4% and 12.2%, respectively. These proportions were 4 to 7 times higher than when the computerized abstracts were the data source. Results of this study indicate that the frequency of clinically relevant POC of elective surgeries in dogs and cats is substantial. Examination of the computerized abstracts of medical records at this hospital allowed us to rapidly identify cases that could be included in the study but the frequency of POC would be significantly underestimated if paper records were not also assessed.
PMID: 8675479 [PubMed - indexed for MEDLINE]
Vet Rec. 2005 Dec 24-31;157(26):829-33.
Complications observed during and after ovariohysterectomy of 142 bitches at a veterinary teaching hospital. Burrow R, Batchelor D, Cripps P. Small Animal Hospital, Department of Veterinary Clinical Science, University of Liverpool, Crown Street, Liverpool L7 7EX, UK.
The clinical, anaesthetic and surgical records of 142 bitches admitted into the primary care clinic at the Small Animal Hospital, University of Liverpool, between January 2002 and August 2004 for routine ovariohysterectomy by final-year students were analysed for complications during and after the surgery. The time taken to perform the surgical procedure was recorded, to allow assessment of the time involved in one-to-one surgical teaching during live-recovery surgeries of client-owned pets. The types of complications were similar to those reported in earlier studies: nine bitches suffered haemorrhage of the ovarian arteries during surgery, and there were four cases of haemorrhage after surgery, 12 cases of wound inflammation and four other types of complication. The rates of intraoperative, postoperative and total complications were 6.3, 14.1 and 20.6 per cent, respectively.
Can Vet J. 2007 Feb;48(2):169-77.
Prevalence of perioperative arrhythmias in 50 young, healthy dogs.
Duerr FM, Carr AP, Duke T, Shmon CL, Monnet E.
Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan. fduerr@colostate.edu
The objective of this study was to assess the type and frequency of cardiac dysrhythmias occurring after routine ovariohysterectomy or orchidectomy in young, healthy dogs by using 2 anesthetic protocols (group I: propofol and isoflurane; group II: thiopental and halothane). Fifty dogs under 2 years of age, judged to be clinically normal by physical examination and standard electrocardiography, were evaluated by using 24-hour ambulatory electrocardiography. The most common dysrhythmias in the postoperative period were 2nd degree atrioventricular block (44%), ventricular premature complexes (44%), and atrial premature complexes (32%). For study purposes, more than 100 ventricular or atrial premature complexes per 24 hours, or any occurrence of R-on-T phenomenon, ventricular or atrial tachycardia were classified as clinically significant arrhythmias. Significant arrhythmias were observed in 9 dogs in the postoperative period, 5 of which were in group I and 4 in group II. All of these dogs were under 1 year of age. The R-on-T phenomenon occurred in 4 dogs in group II and 1 dog in group I. Results from this study show that significant arrhythmias, including R-on-T phenomenon, can occur in the perioperative period in young, healthy dogs undergoing routine surgeries with both protocols used.
Vaccination Considerations
OBJECTIVE: To determine incidence rates and potential risk factors for vaccine-associated adverse events (VAAEs) diagnosed within 3 days of administration in dogs.
DESIGN: Retrospective cohort study.
ANIMALS: 1,226,159 dogs vaccinated at 360 veterinary hospitals. PROCEDURE: Electronic records from January 1, 2002, through December 31, 2003, were searched for possible VAAEs (nonspecific vaccine reaction, allergic reaction, urticaria, or anaphylaxis) diagnosed within 3 days of vaccine administration. Information included age, weight, sex, neuter status, and breed. Specific clinical signs and treatments were reviewed in a random sample of 400 affected dogs. The association between potential risk factors and a VAAE was estimated by use of multivariate logistic regression.
RESULTS: 4,678 adverse events (38.2/10,000 dogs vaccinated) were associated with administration of 3,439,576 doses of vaccine to 1,226,159 dogs. The VAAE rate decreased significantly as body weight increased. Risk was 27% to 38% greater for neutered versus sexually intact dogs and 35% to 64% greater for dogs approximately 1 to 3 years old versus 2 to 9 months old. The risk of a VAAE significantly increased as the number of vaccine doses administered per office visit increased; each additional vaccine significantly increased risk of an adverse event by 27% in dogs < or = 10 kg (22 lb) and 12% in dogs > 10 kg.
CONCLUSIONS AND CLINICAL RELEVANCE: Young adult small-breed neutered dogs that received multiple vaccines per office visit were at greatest risk of a VAAE within 72 hours after vaccination. These factors should be considered in risk assessment and risk communication with clients regarding vaccination.
Math Myth Management
Math Myth Management