Neutering Dogs: Including the use of Suprelorin dog contraceptive
(Neutering ) Spaying and Castration.
The surgical removal of the reproductive organs in both male and female dogs
I began studying and reporting on the effects of early neutering (the generic term for both spaying and castration) after many years of observations and record keeping.
These culminated in a number articles on the outcomes caused by these major operations.
I still get many requests for further information, regarding when, or even if, you should get your dogs “Neutered”.
Therefore this article is meant to be a guide as to what to do. And in what circumstances would neutering be useful and beneficial.
It also points to when it may or may not be in the dog's best interest to be neutered.
It also explains the medical procedures and what hormones are removed or reduced because of neutering.
It is intentionally in depth, as I felt that it would hopefully answer many concerns people have about neutering their pets.
And to question the stance of the vociferous lobby that believes if it moves neuter it.
I also have some concerns, regarding the Veterinary profession's position. Especially the fact that my clients are always complaining about how hard their Vets push for an early neutering procedure.
The Veterinarians state it is always in the dog's best interest. I think It would be far more convinced if it was not so financially lucrative for them.
They state that there has been no long-term clinical work done that shows there are any negative behavioural changes to the dogs. In fact, they say it is always positive to neuter.
This is simply not true! This is an intensive study of over 7,500 dogs on (2) Non-Reproductive Effects of Spaying and Neutering on Behaviour in Dogs This is a quantitative study, that used the Canine Behavioural Assessment and Research Questionnaire © to investigate the impact of spaying/castration in various dog populations.
C-BARQ is a reliable, standardised method for evaluating and screening dogs for the presence and severity of behavioural problems. These included a random sample of 1,552 dogs belonging to 11 common breeds and over 6,000 dogs of various breeds recruited via an online survey.
The results are both shocking and surprising, (though not to me), and show that the majority of our veterinary profession appears not to understand the outcomes of the very procedures they recommend for our dog's behaviour.
In nearly all cases aggression increased with neutering in both male and female dogs. The exact opposite of what we have regularly been told Vets and so-called professionals.
Read this. It is a vet that now deeply regrets performing and recommending Early Neutering.
I am not Vet and i am not clinically trained in any way. This article was created because of m observational concerns, plus research and keeping records that indicated that the majority of my clients had been neutered, many far too early by Vets who have clearly not kept up with peer-reviewed scientific knowledge.
Dr Becker noticed many of her canine patients were developing endocrine-related disorders. After a conversation with an expert in the field of veterinary endocrinology, Dr. Becker realised her practice of insisting on early spays and neuters for every dog patient, had left many of them with serious health problems.
All mammals are born with various hormones. Three of the most important ones are Oestrogen, Progesterone, and Testosterone.
All dogs male and female have these hormones. by what degree each hormone is present determines the sex of the animal.
These are commonly called sex hormones and are related to reproduction.
However, they also play a very important role in other aspects of the animal’s well being.
They allow and create physical, social, and behavioural maturity. Without these hormones the dogs, if immature when the operation is carried out, may not behaviourally and physically reach full maturity. Both physiological and psychological problems may occur because of these early invasive operations.
During my studies, I started noticing frustration, lack of attention, inability to concentrate, and puppy-like behaviour, these traits were far more prevalent in dogs that were neutered and spayed at a younger age, than those who were allowed to mature naturally before neutering.
I call this (paedomorphic behaviour). In other words, dogs that retain perpetual puppy like characteristics. I also observed that bitches spayed too early may be far more interesting to intact males; which may cause the female to become aggressive and protective of this unwanted attention in adulthood.
Despite popular belief, spaying does not calm a female dog down. It may help to calm certain behaviour's in males, but definitely not females. I think it is important to understand that I am not totally against neutering. Though I do have some very grave concerns even in adult dogs.
My major issues are focused on early neutering before the dogs are both physically and mentally mature. That and the fact that it is sometimes recommended for the wrong reasons for the wrong dogs, at the wrong time. Not all dogs benefit from neutering, in fact, many may suffer negative reactions including increased aggression and psychological disorders. In Sweden, it is illegal to neuter Dogs at any age, unless for medical reasons.
Vets have a creed “primum non nocere” or “first do no harm”. Every veterinarian swears an oath to this important creed. Then why are they neutering dogs as young as six weeks of age? Dr Robert Foley and Dr Michael Ferber both well-respected Vets, firmly believe that paediatric neutering is greatly harming our pets. They are called (1) The Angry Vets. Therefore vets doing this procedure are surely not following their professions creed “primum non nocere”
Will Neutering Stop Over Population?
Sweden and other Nordic countries generally do not have a dog roaming problem.
They also do not have dog overpopulation and lots of rescue dogs.
Yet we are constantly told by the neuter everything crowd, that it is the un-neutered dogs that are causing the problem.
The majority of domestic dogs in Sweden are not neutered.
Sweden has quite strict animal breeding laws, and therefore they have minimal problems with pet overpopulation.
In my opinion, the top three contributors to the problem (besides lack of education ) is:
1. Pet Stores
2. Backstreet Breeders.
3. Puppy Farms
In Sweden these problems are not a major issue:
1. You are not allowed to sell cats or dogs in pet stores. That is left to certified breeders ONLY.
That way the spur-of-the-moment purchases of dogs and cats are eliminated. It also means that the buyer is scrutinized before being allowed to buy any pet.
2. Only CERTIFIED breeders are allowed to breed. There are extremely strict laws with hefty fines if not followed, regarding dog breeding.
The breeder is financially responsible for the health of the pup for its first 3 years. That completely eliminates backyard breeders and puppy farms that breed for profit, not health. Under these circumstances, It would no longer be financially viable or feasible to breed.
We do not have a roaming dog problem in the UK. In fact, many of the rescues rehomed in the UK are coming from places like Romania, Thailand, Greece, Ireland, Poland and parts of Africa and the Asian sub-continent.
I believe that places like the UK and America should take note. Instead of mutilating tiny puppies, and affecting the behaviour and health of their immature pets, they should demand stronger breeding laws.
I cannot tell you how many times I have heard people say “Oh just have it done that will sort all the problems out” This statement could not be further from the truth.IS NEUTERING A CURE ALL?
Neutering is a very invasive operation and can lead to numerous physical and mental complications.
It can also considerably worsen the behavioural problem you were attempting to overcome, especially if the dogs has aggression related to fear.
Once castration and spaying have been done it is irreversible. You cannot put back in what you have removed.
I have spoken to numerous people who bitterly regret having the operation done. Unfortunately, by that time, it is too late.
This is especially the case when you have a fearful or timid dog. Spaying or castrating a dog like this can often make the fear behaviour's considerably worse.
The sex hormones and especially testosterone and oestrogen, play a major part in giving dogs an element of calmness, confidence, and well-being. I have seen male dogs that have previously been non-aggressive, suddenly start to attack other dogs and people.
These attacks are normally aimed at both male and female dogs.
Some male and female dogs become withdrawn and terrified of almost everything. Fearful of sounds and movements and sometimes people and dogs they have known and trusted. I treated a female dog recently, a St Bernard. It had to be brought out to me on two leads, with two people hanging on. It had turned so aggressive to both dogs and humans just five days after being spayed.
It had also started attacking and bullying a Poodle, that it had lived with since it was a pup. Fortunately, I managed to work with the dog and it is far better now. I have also had a lot of success with many other females that have reacted badly to spaying.
I actually see quite a few of these aggressive behaviours post spaying each year. Having said that I do deal a lot with aggression. It is, therefore, possible it’s not as common as it may appear, but it does happen. The problem as always is finding a behaviourist who actually understands what has happened, and is able to work with each individual dog, as one size does not fit all. Unfortunately, they are not easy to Unfortunately they are not easy to find.
Despite what the so-called experts say, all behavioural problems do not stem from pack mentality there are many other variables. These one trick ponies would have us believe, that all we have to do is ignore the dog when we come in, eat before it, and then everything is miraculously cured. Absolute garbage, please read the Alpha Myth
Females: The surgeon will make an incision in the middle of the abdomen to locate the reproductive tract, and removes the ovaries and uterus. The medical term for the operation is ovariohysterectomy (OHE). This procedure is carried out under a general anaesthetic. The operation normally requires the removal of the uterine body and horns, the ovaries, and the tubes connecting the ovaries to the horns.
A dog's uterus is a Y-shaped organ with two horns and a body. The procedure may take longer for larger or overweight dogs. Do not bathe your dog or allow swimming for the first ten days after surgery or until after the stitches have been removed.
Males: Both testicles are removed through a skin incision in front of the scrotum. The scrotal sack is left in place, but this often shrinks given a little time. This procedure is also carried out under a general anaesthetic. The operation itself normally takes between 30-40 minutes. Stitches may be used that are dissoluble, others vets use non-dissoluble sutures and these need to be removed about 10 days after the operation. No bathing or swimming until stitches are removed, therefore it may be advantageous to bathe the dogs both male and female before the operation. The medical name for the procedure is orchiectomy.
The concern I have is the one size fits all scenario, that suggests that neutering is the answer to every behavioural problem, I can promise you It isn't.
There are many reasons for a dog's behavioural issues. Hormones may play a part, but not in every case.
For instance, if you are hoping to stop aggression and that aggression is fear based then neutering may often make the dog more fearful therefore more aggressive.
Whatever the apparent behavioural problem, many people will suggest neutering, despite the fact that the dog may be suffering from fear, anxiety, a medical condition, or other non-hormonal reasons for the behaviour.
Neutering can actually have seriously detrimental effects, rather than the positive outcome that is being hoped for.
What Are Sex Hormones
Progesterone is a hormone that the body produces which helps to regulate female's monthly cycle. Men also produce a small amount of progesterone, but it is less important to sexual maturity than testosterone. Progesterone also aids immunity and can reduce inflammation and swelling, it also helps regulate the thyroid gland, and keeps blood-clotting levels at normal values.
It has an impact on keeping bones strong, produces collagen, and helps keep nerves functioning, It can be said to keep people young. Low progesterone levels also decrease the body’s ability to create new bone cells. Hence the problems in old age of Osteoporosis in females, that have gone through what is euphemistically know as “The Change”
Oestrogen: This hormone is considered to play a significant role in females mental and physical health. There are oestrogen receptors in your bones, brain, blood vessels, and the central nervous system. Oestrogen seems to affect lots of different parts of the body and is also important to mood and well-being. Doctors now believe that oestrogen may help keep bones strong and healthy. While estrogens are present in both male and females, it is found in females in significantly higher quantities.
Testosterone: This is a hormone from the androgen group. In mammals, testosterone is secreted in the testicles of males and also to a far lesser extent in the ovaries of females. And is the principal male sex hormone.
In male dogs, testosterone plays a key role in health and well-being, as well as preventing bone problems. Certain behavioural problems are driven by testosterone, namely roaming, inter-dog aggression, this would be normally against other intact males, and certain sexual behaviour's including marking, humping and mounting plus of course mating. Castration may not solve all or even any of the above problems though it certainly can help. In some cases it actually could have a detrimental effect? All three of these hormones are quite vital to maturity in all mammals’, not just dogs.
Progesterone: receptors are found in brain cells, in nerve sheaths, and in bone cells in both male and female dogs. That is a strong indicator that progesterone is involved in their function. It also appears to be involved in a range of other biological activities. Therefore, neutering before both physical and psychological maturity may have a real impact on the health and well-being of your dog.
When Should Yoy Neuter?
Females: If you own a very small dog then you could possibly neuter after two seasons.
In medium dogs two or more seasons would be far more prudent, large dogs three or four seasons and giant breeds at least four seasons unless medical needs suggest otherwise.
If it were my dog even with small dogs, I would never spay until the dog has had at least two seasons.
And only then if it was for medical or behavioural reasons.
You then need to wait three months after the last season before spaying, unless medical conditions require otherwise.
Males: This less clear-cut as they do not have a season to calculate possible maturity.
You need to look at breed and size, and any visual clues such as leg cocking.
A large dog such as a Great Dane should not really be neutered before thirty-six months.
The larger the breed then the later they mature. therefore, a German Shepherd size dog would be about 17 months, a Collie 15 months, a Miniature Yorkshire Terrier about 10/12 months.
Unless of course there are medical or serious behavioural issues to take into consideration. These are all approximated and each dog will vary. Look for leg cocking in the smaller dogs.
When this is fully operational, in other words marking quite high rather than the dismal attempt where they almost fall over then wait a month then you can consider neutering.
What Other Problems May Occur
These are quite complex therefore I am going to give an overview and some snippets, and then direct you to the well-known Vets and experts that make these observations
Neutering at any time can have both positive and detrimental effects. Neutering early, in my opinion, will always cause detrimental effects. What you must take into account is that neutering before maturity may often cause joint, bone and ligament problems.
Have you heard of ACL it means Anterior Cruciate Ligament That is the ligaments that stabilise the knees? This is one of the most common orthopaedic injuries that are seen in today's dogs.
What is the main cause? It was long believed that it was sudden movement caused this problem. This has now been disproved. Please read THIS A small portion of dogs suffers torn cruciate as an injury caused by exertion. The agility, working gundogs and heelwork to music type dogs. However, it is now accepted that the vast majority of the dogs that suffer from this debilitating injury have been neutered.
ACL Anterior Cruciate Ligament and HD Hip Dysplasia is on the increase new Research have now shown that dogs over 4 years old that are spayed or castrated are considerably more likely to suffer cruciate tears and hip dysplasia than dogs that are unneutered.
early neutering removes vital hormones, that will result in spindly legs, narrow chests, and thin skulls. It may also increase the risk of obesity and cause paedomorphic behaviour, lack of concentration, and puppy-like behaviour for most if not all the dog's life. I can also increase the incidence of various cancers.
Neutering when an adult may help certain behaviour's and will stop certain medical conditions. However, it will also increase the chances of other medical conditions occurring such as prostate cancer, thyroid dysfunction, and bone cancer. Obesity is also a problem as neutering will change your dog's metabolism making it more sluggish.
Below are snippets from learned and peer-reviewed articles and papers, from some of the most well-respected professionals in the Pet Industry
CLICK ON THE VETS AND EXPERTS NAME TO GO TO THE FULL ARTICLE
Castration at an early age will cause the dog to become overly tall, as the growth plates in the long bones will not close at the appropriate time; additionally, the dog will lack the breadth of chest. The combination of these two factors sets the stage for your dog to have painful orthopaedic problems.”
"The statement that your dog will not automatically gain weight is rubbish. Removing sexual hormones will change his metabolism and make your dog more sluggish, resulting almost inevitably in weight gain. Also, muscle tone will decline after castration, and the classic result of this is a fat dog in poor muscle tone that ends up having a cruciate ligament rupture in the knee"
“Spayed females have 4 times greater risk of cardiac hemangiosarcomas, and neutered males also show a significantly increased risk for this cancer compared to intact ones.”
“Another cancer Dr. Hahn discusses that deserves mention is prostate cancer because a lot of people erroneously believe that castration prevents this. In reality, it does not. In fact, castrated dogs have up to 4 times greater risk of developing prostate cancer than intact animals.
At the same time, spayed or neutered dogs have a 1.5 to 3 times greater chance of developing bladder cancer. Because of this, rectal examinations and abdominal palpation should always be part of a routine veterinary physical examination.”
“The link between sterilization and osteosarcoma (i.e. bone cancer) is also troubling: Spayed and neutered animals are twice as likely to develop this cancer. Those spayed or castrated before their first birthdays had a roughly 1 in 4-lifetime risk for osteosarcoma and were significantly more likely to develop a tumor than intact dogs.”
Research since 1990 has shown that spay and neuter surgeries may have specific drawbacks as well as benefits. Dogs neutered before puberty tend to have longer legs, flatter chests, and narrower skulls than intact dogs of their breeds because the hormones that regulate sexual activity also interact with hormones that guide the growth of muscles, bones, and tendons.
These physical differences can place more stress on joints and can cause problems for active dogs, especially those in training for agility and those that work in physically stressful jobs.
Additional drawbacks specific to spay surgery include increased incidence of bladder incontinence, triple the frequency of thyroid disease, and a higher risk of some cancers, joint problems, and obesity and adverse reactions to vaccinations.
A recent report by the American Kennel Club Canine Health Foundation reported significantly more behavioural problems in spayed and neutered bitches and dogs which. The most commonly observed behavioural problem in spayed females was fearful behaviour and the most common problem in males was aggression.
A retrospective study of cardiac tumours in dogs showed that there were 5 times greater risk of hemangiosarcoma, one of the three most common cancers in dogs, in spayed bitches than intact bitches and 2.4 times greater risk of hemangiosarcoma in neutered dogs as compared to intact males.
A study of 3218 dogs demonstrated that dogs that were neutered before a year of age had a significantly increased chance of developing bone cancer.(8) A separate study showed that neutered dogs had a two-fold higher risk of developing bone cancer. Despite the common belief that neutering dogs help prevent prostate cancer, at least one study suggests that neutering provides no benefit.
There certainly is evidence of a slightly increased risk of mammary cancer in female dogs after one heat cycle, and for increased risk with each subsequent heat. While about 30 % of mammary cancers are malignant, as in humans, when caught and surgically removed early the prognosis is very good.,
But by far the most startling news to surface this year is the result of a study that shows that keeping ovaries to the age of six years or later is associated with a greater than 30% increase of lifespan in female Rottweilers. (4) (7) Similar studies in humans reinforce this finding. (5),(6)
This is not just Rottweiler, of course, it also relates to all female dogs and appears to be ignored by the spay and neuter crowd that bays for anyone's blood who suggest otherwise.
These people often have no idea what hormones are affected or how physically and mentally it affects the dogs they often condemn to years of sometimes pain and mental anguish. Do they imagine that these hormones are an additional extra like a Sat Nav on a car?
Neutering Male Dogs The Upside:
eliminates the small risk (probably <1%) of dying from testicular cancer
reduces the risk of non-cancerous prostate disorders
reduces the risk of perianal fistulas
may possibly reduce the risk of diabetes (data inconclusive)
Neutering Male Dogs The Downside:
if done before maturity, increases the risk of osteosarcoma (bone cancer) by a factor of 3.8; this is a common cancer in medium/large and larger breeds with a poor prognosis
Increases the risk of cardiac hemangiosarcoma by a factor of 1.6; this is a common cancer and major cause of death in some breeds
Triples the risk of hypothyroidism Increases the risk of geriatric cognitive impairment
Triples the risk of obesity and with it many of the associated health problems
Quadruples the small risk (<0.6%) of prostate cancer
Doubles the small risk (<1%) of urinary tract cancers
Increases the risk of orthopaedic disorders
Increases the risk of adverse reactions to vaccinations
Increases the risk of fearfulness, noise phobias and aggression.
For female dogs, the situation is more complex. The number of health benefits associated with spaying may exceed the associated health problems in some (not all) cases.
On balance, whether spaying improves the odds of overall good health or degrades them probably depends on the age of the female dog and the
relative risk of various diseases in the different breeds.
Spaying Females. The Upside
if done before 2.5 years of age, greatly reduces the risk of mammary tumors, the most common malignant tumors in female dogs
• nearly eliminates the risk of pyometra, which otherwise would affect about 23% of intact female dogs; pyometra kills about 1% of intact female dog
• reduces the risk of perianal fistulas
• removes the very small risk (0.5%) from uterine, cervical, and ovarian tumors
Spaying Females. The Downside
• if done before 1 year of age, significantly increases the risk of osteosarcoma (bone cancer); this is often a common cancer in larger breeds with a poor prognosis.
• increases the risk of splenic hemangiosarcoma by a factor of 2.2 and cardiac hemangiosarcoma by a factor of 5; this is also a common cancer and major cause of death in some breeds.
• triples the risk of hypothyroidism.
• increases the risk of obesity by a factor of 1.6-2, a common health problem in dogs with many associated health problems.
• causes urinary “spay incontinence” in 4-20% of female dogs.
• increases the risk of persistent or recurring urinary tract infections by a factor of 3-4
• increases the risk of recessed vulva, vaginal dermatitis, and vaginitis, especially for female dogs spayed before puberty.
• doubles the small risk (<1%) of urinary tract tumours.
• increases the risk of orthopaedic disorders
• increases the risk of adverse reactions to vaccinations
Laura J. Sanborn, M.S. of Rutgers University,
Why don't we use a Vasectomy for male dogs and a Hysterectomy for female dogs? allowing the testicles and the ovaries to remain, thereby retaining these three vital hormones. This is such a simpler procedure, with the required result of removing the ability to conceive for females.Hysterectomy does not stop seasons, but if the cervix is removed at the same time it prevents pyometra, pregnancy, and bleeding during seasons.
A Vasectomy stops the male dogs from being able to create sperm. Surely this is a far better outcome than Castration and Ovariohysterectomy? Surely it is a no-brainer, so why are Vets and The BVA not recommending this. Especially in the light of the intensive study and research of over 7,500 dogs showing that in almost every case the neutered dogs were the more reactive, moody and aggressive. The very opposite of what we are told is the normal outcome.
Further Medical Research
Those who support early juvenile spay and castration are not quoting the percentages of testicular cancer in un-neutered dogs.
They don’t tell you that the rate is only about 7%, and that’s in dogs that are never neutered.
They also don’t tell you that it is easy to manage and to prevent and cure after maturity.
Behavioural studies show that sterilization increases fearfulness, noise phobias, and aggression.
Other well-documented adverse health effects of de-sexing include increased the risk of bone cancer, hemangiosarcoma, hypothyroidism, and cognitive dysfunction in older pets.
Sterilization confers an increased susceptibility to infectious disease, and also a higher incidence of adverse reactions to vaccines.
Is There An Alternative to Castration?
Suprelorin is a new contraceptive implant for male dogs which offers the advantages of castration without surgery. What has been used in the past was Tardak, which last about three to four weeks and indicates if neutering would be beneficial.
It appears Suprelorin (a fairly new breakthrough) is far more effective and longer lasting. It slowly releases deslorelin, a hormone similar to those used to treat human prostate cancer. The low, continuous dose of deslorelin prevents the production of sex hormones. The biocompatible implant disappears over a period of time and does not have to be removed.
Suprelorin can be used as a ‘road-test’ to mimic the effect that would be seen without undergoing permanent and irreversible surgery. If a favourable response is seen castration can be carried out or Suprelorin could possibly be continued.
Pre-Pubertal's or Juveniles: Because suprelorin/deslorelin suppresses gonadal steroids, its use may delay epiphyseal closure of the long bones, resulting in taller individuals, similar to the effects of pre-pubertal spaying and neutering in domestic dogs and cats.
So be careful regarding the use of this when the dogs are still physically immature. The other downside is that it should not be used indefinitely, as it suppresses all testosterone, unlike castration which only suppresses something like 90% the other 10% is produced through the Adrenal and possibly the thyroid gland. However further study must be done to see if there are adverse effects by removing completely, those hormones produced elsewhere in the body as a result of neutering.
This 10% is important as the bones and other areas of the body could become affected. What About Females: At present, there is no Suprelorin specifically for female dogs, though tests and experiments are being carried out. A product could be available for the females in time.
Stan Rawlinson April 2010
updated regularly last update November 2017
I have written two other articles regarding spay neuter Please see the full articles. One alludes to the practice of the RSPCA and other welfare organisations, and some breeders, spaying and castrating dogs at six weeks of age. In my opinion, this is a national disgrace and the Vets that offer this service should look at the known facts of early neutering and remember that we should all use the adage "First Do No Harm"
Further information and acknowledgements
(1) The Angry Vets.
Clinical and pathologic features of prostatic adenocarcinoma in sexually intact and castrated dogs: 31 cases (1970-1987) Ford W. Bell, DVM; Jeffery S. Klausner, DVM, MS; David W. Hayden, DVM, PhD; Daniel A. Feeney, DVM, MS; Shirley D. Johnston, DVM, PhD; Dept. of Small Animal Clinical Sci; College of Veterinary Medicine; University of Minnesota; 1352 Boyd Ave.; St. Paul, MN 55108
"Castrated dogs had 2.38 times greater risk of developing prostatic cancer than intact dogs when compared with the hospital population."
Laura J. Sanborn, M.S. of Rutgers University, Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs
3. Prostatic disorders in the dog. Anim Reprod Sci 60-61:405-15 2000 Jul 2 36 Refs Johnston SD, Kamolpatana K, Root-Kustritz MV, Johnston GR "Two studies suggest that risk of prostatic adenocarcinoma is increased in neutered, compared to intact male dogs."
4 Zink, Christine, DVM, PhD, DACVP
"Early Spay-Neuter Considerations for the Canine Athlete"; 2005
5. Nolen, R. Scott "Rottweiler Study Links Ovaries With Exceptional Longevity"
JAVMA March 2010 avma.org/onlnews/javma/mar10/100301g.asp
6. Waters, David J., DVM, PhD, Diplomate ACVS "A Healthier Respect for Ovaries"
7. Retaining ovaries may be a key to prolonged life in women and dogs”; DVM Newsmagazine; Dec 5, 2009. veterinarynews.dvm360.com/dvm/ArticleStandard/Article/detail/646838