The Rip Van Wrinkler,
Volume XVIII, Issue I, February 2014

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Between Rocks and a Hard Place?

by Karen P. Christensen
Reprinted with permission by the author, & Eunice Ockerman, editor of the BCOA Bulletin (1st printed in Vol. 48, No.4, Oct Nov Dec 2013)

As dog fanciers, pet owners and breeders, we want the best for dogs, and especially our own dogs. And we want the best for ourselves: the longest, healthiest possible life for our dogs. We carefully select their diet to help them grow and thrive; immunize them against the most virulent pathogens (without over-vaccinating); work to prevent parasites such as fleas, ticks, and worms; keep them in good physical condition and, if we are going to breed them, perform the available tests to assess their genetic traits, and base our selection of mates on minimizing the risk of heritable clinical illness.

Yet it’s unlikely the reproductive status of the dog – intact or sterilized – in relation to its long-term health is considered, except in regard to avoiding the reproductive cancers or infections often cited by veterinarians among the principal reasons to spay or neuter. Pressure to spay or neuter pets, even well-bred purebred dogs carefully selected for companionship or performance, as well as pet-store and neighborhood-bred puppies, begins with the first visits to the vet. If the vet learns you don’t plan to breed, you are likely to be advised they should be sterilized before their likely puberty at about 6 months of age, which has become the gold standard of good pet stewardship in the veterinary community.

If you’re in a hurry to eliminate any risk of unwanted puppies, or your schedule includes events you don’t want to miss because your adolescent puppy is in season, most vets are happy to sterilize them as young as 6 – 8 weeks of age. Puppies born in or surrendered to a shelter at such tender ages may also be sterilized before adoption, and the AVMA has expressed public support for the practice across the board, citing not only the population control benefits but the clinical advantages of quicker healing, fewer complications, and reduced anesthesia needed for these wee ones.

And while it isn’t unreasonable to be concerned about the effects of the very-early spay or neuter on a puppy’s development, there is also evidence, both new and longer-standing, that neutering before puberty, or before full adulthood, or at all in a dog’s life, can have significant tradeoffs in terms of long-term health risks. For many of us, this information regarding the potential adverse health effects of spaying or neutering has been unpublicized, and certainly discounted or ignored by our vets, leading us to think the health disadvantages are small compared to the advantages. There are ample reasons to think that this is not true, based on epidemiological studies of the impacts on cancer, endocrine systems, orthopedic outcomes, and behavioral effects spanning the past 40 years or so.

In fact, some of the information has been available, and nicely summarized, for several years, and additional recent research has supported the earlier findings – and gained attention in the dog world. Unfortunately there are as many questions as answers regarding the findings of some studies, summaries can be inaccurate, and misinterpretation is widespread. Epidemiological studies have some disadvantages that make the interpretation of the data a challenge, and some quite-old studies are frequently misquoted without the benefit of modern electronic availability that allows the lay person to verify or clarify.

I know this only too well because I tried, maybe too hard, to update the state-of-the-science for this topic, and finally decided some of the fine points of the body of literature and the scientific discussion are just not to be covered in a couple of print columns. As a result, I am providing some general information based on the summarized studies and clinical publications, but only diving in to details for a few of them as examples. The articles provided in the popular pet and canine performance magazines over the past couple of years –the articles by Chris Zink, DVM, see HERE, for a comprehensive library of research articles and Dr. Zink’s interpretations of them; and Laura Sanborn’s (2007) summation on www.naiaonline.org -- served as sources of reference materials, and provided a couple of observations, but my focus here is on the relative risks or benefits and drawbacks to neutering at various stages in a dog’s life, including never, using the most recent literature. Interestingly but not surprisingly, there have been no basenji-specific studies conducted. This could be an area for future research if there is a concern that neutering our primitive canines is contributing to the illness burden of the population in a predictable fashion or similar to what is seen in the epidemiology studies.

Health benefits of neutering: It is true, undeniable really, spaying or neutering decreases the risk of most cancers of the reproductive system, certainly the parts removed by castration or ovario(hyster)ectomy, which tend to be spurred on by high levels of sex hormones. Overall, un-neutered (intact) dogs have about a 7% incidence rate of testicular cancer, for example, for which the malignancy/mortality rate is about 10%. It has long been stated spaying reduces the risk of mammary tumors; however the original study in which the analysis was conducted was published in 1969, and has not been examined for bias. A recent review of the full body of literature (Beauvais, et al, 2012) found no evidence for the association between mammary tumors (of any histological type) and neutering, or age at neutering among unbiased studies.

Non-cancer health issues such as pyometra and prostatomegaly are also reduced in neutered pets. As noted above, very early pediatric spay or neuter has clinical advantages including decreased complications, decreased recovery rate, and reduced anesthesia, all of which are considered advantages while not specifically being health measures.

Health hazards of neutering: serious clinical hazards of spay/neuter surgery, including intraoperative errors, infection, stump pyometra, hemorrhage, and anesthesia effects, are relatively rare; less-severe effects such as bruising, self-inflicted trauma to the surgical site, and hematoma or seroma are more common but also easily managed. Urinary incontinence, particularly in females, may be a result of surgical errors or of the alteration of the endocrine influences from sex hormones.

Orthopedic problems may arise as a result of early neutering. Sex hormones are strong signalers of various developmental landmarks, including the closing of growth plates of the long bones of the fore- and hindlegs. Neutering delays the closure of the growth plates, resulting in a longer period of growth of the shaft of the bones, thus resulting in taller dogs with altered angulation. The change in angulation, if severe enough, can result in problems with knees (cranial cruciate ligament, CCL) and hips (dysplasia, HD). A study comparing golden retrievers who were early (< 1 year), late (> 1 year) or never neutered, up to 8 years of age, found that early-neutered dogs had as much as double the incidence rate of HD, and much higher rates of CCL rupture compared to no occurrence in intact dogs and very low rates in late-neutered males (De la Riva, et al, 2013).

Cancers that are prevalent in some breeds, such as hemangiosarcoma (HSA), are notably more common in neutered animals. The study by de la Riva (2013) also evaluated the incidence of HSA, lymphosarcoma (LSA), and mast cell tumor (MCT) in the golden retriever population noted above. Both male and female Goldens neutered before 1 year of age had more than double the rate of lymphosarcoma. Interestingly, late (> 1 year) neutering resulted in higher rates of HSA and MCT in females, and MCT in males, than in never-neutereds. A similar study of Rottweilers reported the incidence of osteosarcoma (OSA), prevalent in the breed, was 3-4 times greater in dogs neutered at < 1 year than in those that were never neutered, and dogs neutered at less than 1 year of age had at least a 25% probability of developing osteosarcoma (Cooley et al 2002).

Autoimmune thyroiditis, from which a greater proportion of basenjis is thought to suffer than the cancers noted above, is also more prevalent in spayed bitches, in particular. And prostate cancer is noted to occur more often in neutered dogs, as well.

So, I am looking at 20-some articles making it clear that neutering a dog early is especially risky with respect to certain cancers , orthopedic, and endocrine disorders. And it is making me a little crazy, because there are distinct advantages to neutering in terms of quality of the dog’s life with me or the life of puppies I’ve bred. Each of my males (2 so far) has been neutered between 3 and 4 years of age – and believe me, their lives became better overall than they were, or would have been, if they were left intact. They had the company of their female household members on an unrestricted basis, their competitive lives (in lure coursing and racing) were not impeded by the hormonal fog of the girls’ seasons, they were more confident about interactions with other dogs, without being combative. They didn’t mark and they don’t guard me the way they had done. My females also benefit from middle-age spaying, without the stress of the seasons or the interruption of their competition.

And I look at my puppy, and his littermates, and I wonder what to do, and what to tell their owners in this regard. I asked them not to neuter without consulting me first, and certainly not before a year, yet one of them was castrated at 8 months – he lives in an upscale urban neighborhood that is dog-friendly but frankly, not dog-savvy, as they freak out over a raised hackle or lip and his owner was facing losing both her dog walker and her dog park privileges while her beloved puppy goes through adolescence. From a previous litter, the owners of a bitch puppy were essentially terrorized into spaying before a year by an overzealous veterinarian. It’s fine to try to be an advocate for the best approach for an individual dog, but it would be foolish to anticipate I have the loudest voice or the last word. Ultimately, behavioral, performance, and convenience factors (and the integrity of a breeding program or kennel name) need to be taken into consideration when weighing health risks against how we live with our dogs day to day. I certainly look forward to the day I can get the puppy-boy collected/frozen, and neutered.

It turns out that we can have some confidence that, overall, spaying or neutering actually contributes to a longer life (by as much as 2 years). The health consequences of reproductive capability was evaluated by Hoffman, et al (2013) using the Veterinary Medical Database (VMDB) for the years 1984 – 2004. They looked at cause of death (and longevity) of over 40,000 intact dogs and a similar number of neutered dogs ages one year and older, and noted the positive effect of neutering on lifespan, while also pointing out the various causes of death and how they shift from traumatic injury and infectious disease in intact dogs, to cancers and immunopathologic illnesses in sterilized ones. I do wish they had also evaluated whether there were longitudinal (time-related) changes in the incidence of the infectious and traumatic causes, concurrent with better immunization and pet stewardship –or if the incidence of dog fighting, hit-by-car, and other traumatic injuries may really not be decreasing, and the huge populations of shelter and rescue dogs infected with distemper (the most common infectious cause of death in unneutered dogs) may skew the results of that cause of death. And, it occurs to me the traumatic and infectious illnesses can be more easily prevented than cancers, by conscientious stewardship and immunization – maybe the categories of dogs that died in these ways could be subdivided to give us a clearer picture of which dogs are most at risk, to help us understand whether our own coddled creatures are in fact high risk during their intact years? While the cancers and autoimmune issues that are more common in neutered pets may also not be as prevalent in our breed – how much do we want to know if these factors, rather than the hereditary illnesses that have been the focus of our sponsored health research in the past few years, are controllable contributors to the health and longevity of our dogs?


Karen taking a day away from her usual work, to teach in a nearby school.

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