An Apatosaurus plodding towards the tar pits?
An emotional topic, emotive and controversial. Almost as controversial as real food. Yet, few think about the consequences. Surely it is not good medicine when those who are supposed to guide and support pet parents insist that removing vital organs, which have many functions beyond reproduction, in order to prevent something that may or may not happen? We are all conditioned to believe that de-sexing our fur kids is perfectly normal and even important for multiple reasons.
Perhaps the act should be called a heresy. There are good reasons to be sure, one cannot teach fur kids about safe sex. However, traditional protocols might not be the only way forward. More appropriate breed-based protocols and perhaps improved techniques based on human vasectomy procedures is required in our modern informed age. We realise that all medical procedures have risks attached, but vasectomies are safe in general, and do not cripple the immune system. We are not against the concept of de-sexing; we question the validity of the current protocols that advocate sterilization at extremely young ages.
One recent study on Golden Retrievers by Torres de la Riva et al at UC-Davis 1 , found that males neutered before the age of 12 months were twice as likely to suffer from hip dysplasia, and that three times more early-neutered males suffered from lymphosarcoma (3rd most common cancer diagnosed in dogs) than intact males. On the other hand, late-neutered (after 12 months) females suffered from hemangiosarcoma (Wikipedia) four times more than intact or early-neutered females. In either case, intact dogs came out better than those that had been neutered.
Read More: Lymphosarcoma in Dogs, Veterinary Hospital of the University of Pennsylvania (OncoLink)
As stated by Confucius, “life is really simple, but we insist on making it complicated”. To further complicate our understanding of this topic, another study by Hoffman, Creevy and Promislow2 , found a correlation between reproductive sterilization and a longer life span when neutered dogs were compared to intact dogs. In part, that increased longevity was associated with a decreased risk of death from infectious diseases and trauma. They also found that neutering was correlated with an increased risk of death from cancer.
But this GoT season does not end there. A study published in 2009 by Waters found that female Rottweilers neutered after the age of four were more likely to achieve “exceptional longevity” than females neutered at an earlier age.
Read More: Rottweiler study links ovaries with exceptional longevity, S. Scott Nolen (JAVMA)
What are we to make of these findings? Do they suggest that early, and in the case of rescues and shelters, “very early”, neutering of animals is a bad idea? Should pet parents forgo de-sexing their pets in order to increase their life span or prevent joint and tissue injuries? Confusing indeed! It seems that these studies have found correlations, not causal effects, and one can never be too careful about correlations. Keep in mind, correlations don’t prove causality.
One does not need to be a veterinarian or physiologist to suspect that removing hormone-producing organs has a profound effect on a body’s physiology, beyond that of eliminating the potential of reproduction. Natural selection is a conservative process, and it is rare for any hormone to play only one role in the body. Androgens (Wikipedia) produced in the testes play a role in muscle and skeletal development3 . Estrogens (Wikipedia), we’re told, affect the urinary tract, the heart and blood vessels, bones, breasts, skin, hair, mucous membranes, pelvic muscles, and the brain. It is therefore reasonable to wonder what the effects truly are of neutering animals at young age, sometimes as young as a few months of age. We already know that extremely early neuters lead to more long bone growth in dogs, but what of other effects? What do we really know?
A 2007 systematic review 4 by Laura J. Sanborn of more than 50 peer reviewed studies forms the basis for this discussion . It appears that no compelling case can be made for de-sexing most male dogs, specifically young and adolescent male dogs, in order to prevent future health problems. The number of health problems associated with neutering may exceed5 the associated health benefits in most cases.
Read More: Assumptions about a mainstay of companion animal practice are called into question, R. Scott Nolen (AVMA)
The following was highlighted in the review.
On the positive side, de-sexing male dogs:
- 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).
On the negative side, de-sexing male dogs:
- if done before 1 year of age, significantly increases the risk of osteosarcoma (bone cancer); 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;
- triples the risk of hypothyroidism;
- increases the risk of progressive geriatric cognitive impairment;
- triples the risk of obesity, a common health problem in dogs with many 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 orthopedic disorders;
- increases the risk of adverse reactions to vaccinations.
For female dogs, the situation is more complex. The number of health benefits associated with spaying may exceed the associated health problems in some, but not all, cases. Whether de-sexing 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.
On the positive side, de-sexing female dogs:
- 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 dogs;
- reduces the risk of perianal fistulas;
- removes the very small risk (≤0.5%) from uterine, cervical, and ovarian tumors.
On the negative side, de-sexing female dogs:
- if done before 1 year of age, significantly increases the risk of osteosarcoma (bone cancer); this is 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 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 tumors;
- increases the risk of orthopedic disorders
- increases the risk of adverse reactions to vaccinations.
The studies that formed part of the review are found in the veterinary medical literature and investigate the long-term physical risks and benefits associated with de-sexing in dogs. The systematic review concludes:
“One thing is clear – much of the spay / neuter information that is available to the public is unbalanced and contains claims that are exaggerated or unsupported by evidence. Rather than helping to educate pet owners, much of it has contributed to common misunderstandings about the health risks and benefits associated of spay / neuter in dogs.”
One of the misunderstandings propagated by the veterinary community is the myth that de-sexed dogs enjoy a longer and healthier lifespan than their intact counterparts.
Instead, current data confirms that dogs in Europe tend to live longer for several reasons other than de-sexing. One major difference is that pets are not sterilized at nearly the rate the US, or South Africa, are. Germany, for example, has very strong animal protection laws and it is illegal to surgically alter a pet, including castration, ear cropping and tail docking, unless there is a sound medical reason to do so.
In all Scandinavian countries (Sweden, Norway, Denmark, Finland) routine surgical sterilization of pets is also prohibited. Vets in England report that it is very rare in Britain and that most requests for the procedure are from US-expats. India and Italy have moved to humanely sterilize their street dogs with a chemical injection.
And yet, in South Africa, we love to follow the Americans. Global statistics show that our pets are getting sicker, suffering from various illnesses and the claim that traditional castration increases longevity is highly debated and contested. The health cons associated with castration (including the actual surgery risks) far outweighs the pros. And castration as a preventative for future health problems such as certain cancers is highly questionable.
“By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest.”~ Confucius
The 2013 UC Davis study states:
“Because [spaying and] neutering can be expected to disrupt the normal physiologic developmental role of gonadal hormones on multiple organ systems, one can envision disease syndromes…to possibly be affected by [spaying and] neutering* as a function of gender and the age at which [spaying and] neutering is performed.”
*Note: in this study the term “neuter” refers to both spaying of females and neutering of males
Abnormal bone growth due to early castration
Current protocol recommends neutering males at the age of four to six months and to spay females before their first heat cycle. Numerous studies done in the 1990s and in 2000 showed that dogs traditionally castrated before one year of age grew significantly taller than intact dogs. The removal of estrogen-producing organs in immature dogs’ influences bone growth and development. It causes the growth plates to remain open and dogs continue to grow, winding up with abnormal growth patterns and bone structure.
Joint Disease, Hip Dysplasia and Cruciate Ligament Tears (CCL)
A study published over 10 years ago in the Journal of the American Veterinary Medical Association 6 , showed that de-sexed dogs, especially when the procedure is done at an early age, were more prone to hip dysplasia and joint diseases7 . Another study concluded that spayed and neutered dogs had a significantly higher incidence of CCL rupture than their intact counterparts, particularly large breed dogs.
Cancer and Immune System Issues
Studies have been done on rottweilers, golden retrievers and vizslas, looking at traditional spaying and neutering practice and its link to cancer. All the results combined show a significantly increased risk for developing mast cell cancer, lymphoma, hemangiosarcoma, bone cancer, prostate cancer8 and other cancers in castrated animals9.
Based on these studies, on average, dogs have a five times higher incidence of getting cancer, regardless of the age of castration. We are told that de-sexing can reduce certain cancers, but ovarian cancer for example is so rare that the ovaries should not be removed just to try to prevent it. Although the removal of the testes does eliminate death from testicular cancer, the risk is very small, less than one percent. In 2012, the Royal Veterinary College in the UK looked at the possible risk reduction of canine breast cancer (mammary neoplasia) 10 and was not able to validate this theory. That leaves the elimination of the risk of pyometra (infection of the uterus) as the sole health benefit for females.
Ask yourself this: Why is cancer skyrocketing among our pets, while we have been de-sexing so many animals for decades? In the US, 83% of all pets are altered! Pity there are no statistics available for South Africa. If castration is reducing the risk of cancer, should cancer incidences not decline?
Understanding cancer is the key: Genes play a role, but only in about 10 percent of cases. And whether these genes are turned on or off depends on the lifestyle we chose for our pets. All living beings have cancer cells; it is a natural cycle of our bodies that cells die off and are renewed. Cancer can only develop when the immune system is compromised. For more, watch the eye-opening TED presentation by Rodney Habib: “Why Don’t Dogs Live Forever?”.
Hormone / Endocrine Imbalances
In female dogs, spay is “instant menopause” and immediately shuts off the supply of protective hormones that are involved in much more than just reproduction. Hormones are like messengers, regulating numerous bodily functions like cell metabolism, enzyme activity, growth, development, metabolic rate, homeostasis, cholesterol levels, energy levels, muscle tone, cognition, behaviour, sexual rhythms, reproduction and, most importantly, the immune system.
Undoubtedly de-sexing causes hormone imbalances that lead to irreversible metabolic health complications, like sex hormone inequity, thyroid and adrenal diseases, as well as urinary problems. In addition, our pets are exposed to environmental contaminants like xenoestrogens (Wikipedia), which are imitate hormones, compromising the endocrine system even more.
If you own a breed that is genetically prone to thyroid disease, you should consider a healthier alternative to castration. Unfortunately, many vets are still practising old standards by not doing a full thyroid panel, and as a result many pets are misdiagnosed and suffering needlessly.
Mental health concerns and behavioural issues
Dogs in the wild do not have any behaviour issues – they develop these solely by living with us humans. Contrary to common belief, castration is not an easy overall behaviour fix. More recent animal behaviour studies11 prove that it only curbs certain problems, such as marking, mounting, howling, roaming tendencies, and inter-male aggression if an in-season female is around.
Nearly every woman has experienced endocrine issues at some point and understands that hormones are very powerful and can affect our personality and behaviour. It’s no different for our pets and removing a quarter of the endocrine system is not in their best interest. Before you consider de-sexing because of behaviour issues, you should rule out any potential medical problems first. Particularly thyroid issues can be worsened by the traditional de-sexing approach.
Performing a castration can also have negative effects on your dog’s confidence level as testosterone is significantly lower. As a result, the dog can become more timid, excitable or hyperactive, aggressive (in the form of fear biting) and develop noise phobias, separation anxiety, submissive urination or other undesirable sexual behaviours.
Are there alternatives?
We believe there are and would love to see more vets in South Africa offering alternative procedures.
Vasectomy for males
The first vasectomy on a dog was performed in 1823. It is a simple procedure of 30 minutes, where through an incision in front of the testicle the spermatic duct (vas deferens) are clamped, cut, or sealed and cauterized on the ends with a laser. This prevents sperm from being ejaculated but preserves normal endocrine function.
Tubal ligation for females (having the tubes tied)
Similar to the vasectomy, in females the fallopian tubes are cut, blocked or tied to prevent movement of the egg to the uterus and also blocks possible sperm from fertilization. Dogs with tubal ligation keep their ovaries and uterus, have normal hormone production and maintain their heat cycles.
Ovary-sparing Spays (OSS) for females (hysterectomy)
Sometimes called “partial spay” or “modified spay”, this procedure removes the uterus, while preserving the hormone-producing ovaries. This also removes the nuisance of bleeding during heats, along with the risk of infection or cancer of the uterus.
Chemical Sterilization / Birth control pill
Some animal shelters already use a calcium chloride-based compound called Calchlorine that has been around since the 1970s to chemically sterilize pets. It is injected into the testicles to prevent sperm production and reduce testosterone levels. It is a commonly available compound and cannot be patented, so pharmaceutical companies have developed the injectable sterilization agent Zeuterin / EsterilSol for male dogs.
Progestin contraceptives or birth control pills are administered either orally or as an injection and are mostly used on females.
Our findings does present a paradox. Does it make any sense that you would take a procedure you know to be extremely harmful to humans (and in some cases illegal) and mandate that it be performed on each and every dog – with almost NO exception and without the benefit of any peer- reviewed research establishing its safety? Would you then promote this procedure as actually being good for dogs? Contrast these overly invasive and often unsafe sterilization procedures with those we safely perform on humans, i.e., tubal ligations on females and vasectomies on males. This begs the question, why can’t vasectomies and tubal ligations be performed on our canine best friends? The short answer is, “They can!”.
Ultimately as a responsible dog or cat guardian and / or pet parent, it should be your personal choice whether to sterilize your pet, when and how. Your decision should be based on your pet’s individual health situation, breed, behaviour and temperament and on your capability to train and control your animal.
“Hopefully, it will never again be possible to repeat the studies reviewed in this paper, as in more recent times we have used different means of expressing man’s inhumanity to man”.
Articles and Videos
We highly recommend reading the book “The Canine Thyroid Epidemic,” by Dr. Jean Dodds and Diane Laverdure (Amazon).
- The Neutering Controversy: Understanding Data on Hormones, Behavior and Neoplasia (TVP);
- Baldness and Hormone-Related Skin Disorders in Dogs (PetMD);
- “Tumors in Domestic Animals” by Meuten DJ 4th Edn. Iowa State Press, Blackwell Publishing Company, Ames, Iowa [PubMED];
- “Cancer Epidemiol Biomarkers” by Cooley DM, Beranek BC, Schlittler DL, Glickman NW, Glickman LT, Waters D, Prev. 2002 Nov [PDF];
- “Host related risk factors for canine osteosarcoma” by Ru G, Terracini B, Glickman LT. Vet J. 1998 Jul [PubMED];
- “Effect of gonadectomy on subsequent development of age-related cognitive impairment in dogs” by Hart BL. J Am Vet Med Assoc. 2001 Jul 1 [PubMED];
- “The relationship of urinary incontinence to early spaying in bitches” by Stocklin-Gautschi NM, Hassig M, Reichler IM, Hubler M, Arnold S. J. Reprod. Fertil. Suppl., 2001 [PDF];
- “Urethral sphincter mechanism incompetence in male dogs: a retrospective analysis of 54 cases” by Aaron A, Eggleton K, Power C, Holt PE. Vet Rec., 1996 [PubMED];
- “Hypothyroidism in dogs: 66 cases (1987-1992)” by Panciera DL J. Am. Vet. Med. Assoc., 1994 [PubMED];
- “Long-term outcome of gonadectomy performed at an early age or traditional age in dogs” by Howe LM, Slater MR, Boothe HW, Hobson HP, Holcom JL, Spann AC.. J Am Vet Med Assoc. 2001 Jan 15 [PubMED];
- “Behavioral and Physical Effects of Spaying and Neutering Domestic Dogs” by Parvene Farhoody @ M. Christine Zink, May 2010 [PDF];
- “Correlation of neuter status and expression of heritable disorders” by Janelle M. Belanger1, Thomas P. Bellumori1, Danika L. Bannasch2, Thomas R. Famula1 and Anita M. Oberbauer1, Belanger et al. Canine Genetics and Epidemiology (2017) [BMC];
Dr. Becker: The Truth About Spaying and Neutering
Dr. Becker and Dr. Valente Talk About Spaying and Neutering;
Why Don’t Dogs Live Forever? | Rodney Habib | TEDxNSCCWaterfront
References and Research
- 1.Torres de la Riva G, Hart BL, Farver TB, et al. Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers. Williams BO, ed. PLoS ONE. February 2013:e55937. doi:10.1371/journal.pone.0055937
- 2.Hoffman JM, Creevy KE, Promislow DEL. Reproductive Capability Is Associated with Lifespan and Cause of Death in Companion Dogs. Helle S, ed. PLoS ONE. April 2013:e61082. doi:10.1371/journal.pone.0061082
- 3.Salmeri K, Bloomberg M, Scruggs S, Shille V. Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development. J Am Vet Med Assoc. 1991;198(7):1193-1203. https://www.ncbi.nlm.nih.gov/pubmed/2045340.
- 4.Spivak M. Recent Research Raises Concerns Regarding Early Spaying/Neutering. 2015. doi:10.13140/RG.2.1.4791.9449
- 5.Spain C, Scarlett J, Houpt K. Long-term risks and benefits of early-age gonadectomy in dogs. J Am Vet Med Assoc. 2004;224(3):380-387. doi:10.2460/javma.2004.224.380
- 6.Whitehair J, Vasseur P, Willits N. Epidemiology of cranial cruciate ligament rupture in dogs. J Am Vet Med Assoc. 1993;203(7):1016-1019. https://www.ncbi.nlm.nih.gov/pubmed/8226247.
- 7.Slauterbeck J, Pankratz K, Xu K, Bozeman S, Hardy D. Canine ovariohysterectomy and orchiectomy increases the prevalence of ACL injury. Clin Orthop Relat Res. 2004;(429):301-305. doi:10.1097/01.blo.0000146469.08655.e2
- 9.Ware W, Hopper D. Cardiac tumors in dogs: 1982-1995. J Vet Intern Med. 1999;13(2):95-103. doi:10.1892/0891-6640(1999)013<0095:ctid>2.3.co;2
- 10.Salas Y, Márquez A, Diaz D, Romero L. Epidemiological Study of Mammary Tumors in Female Dogs Diagnosed during the Period 2002-2012: A Growing Animal Health Problem. PLoS One. 2015;10(5):e0127381. doi:10.1371/journal.pone.0127381
- 11.Zink M, Farhoody P, Elser S, Ruffini L, Gibbons T, Rieger R. Evaluation of the risk and age of onset of cancer and behavioral disorders in gonadectomized Vizslas. J Am Vet Med Assoc. 2014;244(3):309-319. doi:10.2460/javma.244.3.309