Laurie's Blogs.


May 2022

Spaying and Neutering Decision Making

Laurie Edge-Hughes, BScPT, MAnimSt, CAFCI, CCRT

So, I received a couple of responses to my recent Four Leg Rehab Minute video.  The intention of the video was to highlight that we, as rehab practitioners, can be part of the conversation in regards to WHEN to spaying or neuter a dog.  However, it might be beneficial to add some commentary to that sentiment.  


Let’s look at some papers.


The paper that began my discussion regarding the fact that evidence is now becoming available to help with the decision making on when to spay and neuter is the following:

Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence


This paper looks at the age of spaying or neutering in 35 different dog breeds and comes up with a table of timelines and description of whether a dog should be altered at any time, beyond 6-month, beyond 11-months, or beyond 23-months depending on breed, or sex of the animal.  It studied the effects of time of gonadectomy as it relates to urinary incontinence, cancer (lymphoma, hemangiosarcoma, mast cell tumour, or osteosarcoma), or joint issues (elbow dysplasia, hip dysplasia, or cranial cruciate ligament tears).  It only pertains to these 35 breeds, but this is a fabulous start I think!  Check it out!


The next paper was by the same authors, but this time looked at mixed breed dogs in five weight categories and compared all of the factors mentioned above. 

Assisting Decision-Making on Age of Neutering for Mixed Breed Dogs of Five Weight Categories: Associated Joint Disorders and Cancers


Here are the highlights from that paper:  

“There was no significant increased occurrence of one or more cancers, compared with intact dogs, in any weight category. However, in the three categories of dogs weighing 20 kg or more, neutering before 1 year generally was significantly associated with risks of one or more joint disorders above that of dogs left intact, commonly to 3 times the level of intact dogs, with sex differences in the degrees of joint disorders associated with neutering.”  “  “Dogs in the two weight categories


Another paper sums up what I was trying to say in my video: 

A literature review on the welfare implications of gonadectomy of dogs


“Although information about the risks associated with gonadectomy has been reported in the past, the recommendation for gonadectomy as a blanket policy is increasingly controversial, with greater focus on possible ramifications for individual animals in addition to the canine

population as a whole. These risks and benefits must be revisited as new information becomes available. Because of the substantial national problem of homeless animals, shelter and rescue organizations are encouraged to spay and neuter dogs prior to adoption to prevent those animals from further contributing to the population of unwanted animals. Similar to other areas of veterinary medicine, it is the responsibility of veterinarians to use their best medical judgment (on the basis of each animal’s ownership, breed, sex, and intended use) to weigh both the potential risks and benefits when determining whether gonadectomy is appropriate and, if so, the appropriate age for the surgery.”


Another study has looked specifically at risk factors for the development of prostate cancer in neutered male dogs.

A Population Study of Neutering Status as a Risk Factor for Canine Prostate Cancer


This study looked at the incidence of male dogs with urinary bladder transitional cell carcinoma (TCC), prostate adenocarcinoma (ACA), prostate TCC, prostate carcinoma (CA), and prostate tumors.  “Epedemiologic data in the VMDB [Veterinary Medical Databases] clearly establish castration as a risk factor for development of prostate cancer in dogs. Risk varies by breed, suggesting that genetics play a role in the development of these diseases. Factors are similar for urinary bladder TCC as for prostate cancer and prostate TCC, lending support to a urothelial or ductular origin of many prostate tumors of dogs.”


This is interesting, but should be taken in context.  The previously cited literature review had noted, “… the rarity of prostate neoplasia in male companion animal dogs, effectively negates concerns a veterinarian might have about neutering.”


One study evaluated behavioural issues in correlation with ‘prolonged lifetime exposure to gonadal hormones’ (PLGH).  

Behavioural risks in male dogs with minimal lifetime exposure to gonadal hormones may

complicate population-control benefits of desexing 


“Only 2 behaviours, indoor urine marking and howling when left alone, were significantly more likely in dogs with longer PLGH.  In contrast, longer PLGH was associated with significantly reduced reporting of 26 (mostly unwelcome) behaviours. Of these, 8 related to fearfulness and 7 to aggression.”  The publication discussed how the partial or complete denial of puberty might reduce marking, but have other unwelcome consequences.  As such, discussion is important, as is looking at the individual dog.


The following study, looked at neutering status and heritable disorders.

Correlation of neuter status and expression of heritable disorders 


Now, they didn’t look at ‘early or late’ neutering, just neutered or not.  Essentially they found the following:  “Neutered dogs were at less risk for early and congenital conditions (aortic stenosis, early onset cataracts, mitral valve disease, patent ductus arteriosus, portosystemic shunt, and ventricular septal defect) than intact dogs. Neutering was also associated with reduced risk of dilated cardiomyopathy and gastric dilatation volvulus in males. Neutering was significantly associated with an increased risk for males and females for cancers (hemangiosarcoma, hyperadrenocorticism, lymphoma, mast cell tumor, and osteosarcoma), ruptured anterior cruciate ligament and epilepsy. Intervertebral disk disease was associated with increased risk in females only. For elbow dysplasia, hip dysplasia, lens luxation, and patellar luxation neutering had no significant effect on the risk for those conditions. Neutering was associated with a reduced risk of vehicular injury, a condition chosen as a control.”


Okay, so I hope this is a beneficial summary of some articles that provide background to help direct your thinking and advice in regards to WHEN to spay or neuter a dog.  It’s not clear cut.  However, I still hear owners say, “We want to get our dog spayed before her first heat cycle… or neutered before he finds out he’s a male.”  I’ve heard owners tell me, “My vet said that I definitely don’t want to have to deal with a dog in heat.”  So, my point is, that as rehab practitioners, we can be part of the discussion, taking into account, size, breed, sex, athletic goals, etc.  


On that note, happy chatting this week!

Cheers,  Laurie