Continuing to evaluate the timing of neutering/spaying
(Feb. 25, 2025) — Last month, I started a discussion of neutering/spaying dogs and cats and how important it is to do our part to help prevent pet overpopulation. The flip side of that coin brings up the question: When might one want to delay or avoid a spay or neuter in pet dogs and cats?
In my last column, I reviewed the benefits of spay and neuter for several health concerns. From a practical standpoint for your veterinarian, spays are much simpler when the puppies are still immature as compared to after they are reproductively mature – especially in large breed dogs.
There are few benefits to leaving cats intact, except if they are intended to become breeding animals, for all the reasons mentioned in January’s column (females yowling on and on until they are bred and cycling in and out of estrus/heat, urine spraying, tomcat smell, cat fights/abscesses, tendency to roam). For a time, we veterinarians thought that later neutering of male cats might lead to less incidence of urinary blockage, but this has been shown not to affect the occurrence of this serious disease.
Incidentally, stray cats who live in colonies should be managed via a Trap-Neuter-Release (TNR) program to minimize enlargement of the colony. These cats often have an ear flap clipped and sometimes a small tattoo on the belly of females once they are spayed/neutered so as not to have to recapture them in the future.
For a recently adopted puppy or kitten, working with your veterinarian on when to neuter is an important part of the wellness exam and veterinary-client-pet relationship. A spay or neuter can often be performed as early as a few weeks to a month after the pup’s final vaccine visit, and for females, a spay before her first heat cycle almost completely resolves the risk of mammary cancer.
However, your vet might sometimes recommend waiting until a year of maturity, sometimes even longer, since a few canine breeds appear to have health benefits from a delay in spaying and neutering to allow more complete maturation before neutering takes place. Gaining full maturity may help prevent some hormonal, anatomic and orthopedic conditions, as well as certain cancers in some breeds.
Having said that, studies have been mixed and there remain pros and cons.
As one example of a potential benefit, delaying neutering in some large to giant breed dogs may decrease the risk of hip dysplasia or cruciate ligament rupture. Delaying spays and neuters in golden retrievers, German shepherds, boxers and Rottweilers, to name a few, may be beneficial in lessening the risk of certain cancers in addition to orthopedic and hormonal (hypothyroidism, for example) issues.
Each of the breeds mentioned have a higher incidence in certain cancers (lymphoma, mast cell tumors, hemangiosarcoma) that may benefit from a delay in spay or neuter, but these conditions tend to be both breed specific and gender specific, and the data remains somewhat mixed. This is why your veterinarian can be helpful in figuring this all out.
One also must consider behavioral concerns. As males mature, testosterone levels climb, and full maturity can sometimes lead to fighting or other aggressive behavior. The converse to this is if one adopts an adult male dog who has aggression issues, neutering can sometimes curtail that bad behavior.
It is important to know there are a few unintended consequences of spays and neuters. One example is that urinary incontinence can occur following spay. It doesn’t seem to correlate with early spays specifically and can be suppressed with hormone replacement therapy. Weight gain can occur in the first two years post-spay or neuter, but the data shows weights even out regardless of neutering status and can be mitigated by adjusting feeding plans. Keeping a neutered/spayed dog slender should be a manageable thing, which also helps with orthopedic issues as an added bonus.
Of course, there are some situations in which keeping animals intact is completely appropriate. Knowledgeable people dedicated to preserving and improving blood lines of their beloved breeds will not likely be spaying and neutering animals in their breeding program or those who are being shown. In these dogs, spaying and neutering may be performed for health-related issues such as pyometra, mammary or uterine cancers in females, or prostatitis or testicular tumors in males, when and if these conditions arise.
Well-behaved male dogs who get along with others and are not allowed to roam can lead a full healthy life intact. In females, intact dogs who are well supervised when they are in heat can also be managed as such, though it takes vigilance and knowledge.
In the last two columns, I have explored some of the ins and outs of choosing when and if to spay and neuter. As I said last month, in most situations, I call this a “when” and not an “if” for ease of pet ownership and pet longevity. But having more information allows the pet owner to make an informed and responsible decision for their animals.
Send questions and comments by email to Micki McCabe Walls at drmccabevet@gmail.com.
Related story: Despite recent research, spaying and neutering early still a good option.
Micki McCabe
Micki McCabe Walls, DVM, DACVIM, FAAVA, is a long-time Clayton resident. The recently retired local veterinarian has an interest in internal and integrative medicine.