The times they are a changing.  Every now and then in the course of medicine, we get new research that guides us to change our ways of thinking and how we practice.  And we live in exciting times because now is one of those moments.  New research has been presented regarding potentially more appropriate age of spay or neuter surgery for your dog, most notably larger dogs.  Don’t worry, I’ll also discuss cats.

age of spay or neuter can affect many heath factors

No, I haven’t changed my stance that the procedure should still be done.  But I agree and am glad to see some changes in the timing of when we as veterinarians recommend the surgery happen.  Let’s explore this and try make sense of the differences.

The first thing you have to look at is what breed, or at least size, of dog you have.  The next thing you have to consider is what are your goals you’re trying to achieve with your pet’s health – joint development & health, cancer risks, behavior, etc.  Lastly, we need to consider their lifestyle.  Much of the research focused on some common breeds (Golden Retrievers, Labrador Retrievers , Rottweilers, Viszlas) but we can try to extrapolate from this data.  So let’s discuss….

Bones & Joints

When you spay or neuter an animal, you are affecting their hormones.  Doing this too soon may affect growth by making females taller or cause malformations in the hips, knees, or elbows of both genders.  Waiting until skeletal maturity provides a better foundation especially when trying to lower the risk of something like hip dysplasia.  Spaying/neutering also has shown a higher risk if neutered at an early age.  This is more of an issue for larger dogs where as smaller dogs reach skeletal maturity at a younger age.

hip dysplasia, photo from

Cancer Risks

In school, much of the focus involving cancer and spay/neuter was involving mammary or testicular cancers.  While this is important, the research has extended to include neoplasias such as osteosarcoma (OSA), lymphoma, and hemangiosarcoma (HSA).  While delaying the surgery may slightly increase the risk of reproductive tumors, it can also potentially reduce or increase the chances of one of those other nastier tumors developing.


Not all intact animals are aggressive or bad.  But some of them could benefit from the loss of some hormones while also helping reducing the problem of pet overpopulation.  Particularly in the Vizsla breed, early spay/neuter has been documented to show increased storm phobias, separation anxiety, hyperactivity, and fear biting.  In other breeds in general, intact males have been found to have slower progression of cognitive disease issues.

Lifestyle & Other Factors

If you’ve got litter mates of opposite gender, they shouldn’t be bred so unless you are certain you can keep them apart when the girl is in heat, somebody better get fixed sooner rather than later.  Pyometra (uterine infection) is still a very real disease.  It can be fixed sometimes, but not all, and will cost you more in the long run as well as any illness or pain issues your pet would have to experience.  And in general, pets who have been spayed or neutered have a longer life expectancy but may get other illnesses associated with old age…an older age they might not have made it to if they weren’t spayed or neutered.

Check the summary chart below to assess increased risk for a few conditions based on age at the time of neutering or spaying.  It is not meant to be complete or encompass every breed or condition.

Condition Male Female
Hip Dysplasia less than 1 year old (GR, GSD) less than 1 year old (GSD), less than 2 years old (LR)
Torn ACL less than 1 year old (GR, GSD), less than 2 years old (LR) less than 1 year (GR, GSD)
Mammary Cancer greater than 1 year old (GSD and most dogs)
Lymphoma less than 1 year (GR) but concern at any age vs. intact status (Vizslas) less than 1 year (GR) but concern at any age vs. intact status (Vizslas)
Osteosarcoma less than 1 year old (Rott) less than 1 year old (Rott)
Mast cell tumors concern at any age vs. intact status (Vizslas) concern at any age vs. intact status (Vizslas), greater than 1 year old (GR)
Hemangiosarcoma greater than 1 year old (GR), concern if older than 1 year vs. intact status (Vizslas) concern at any age vs. intact status (Vizslas)
Behaviour issues & phobias greater chance of developing if less than 6 months old (Vizslas) greater chance of developing if less than 6 months old (Vizslas)
Chart adapted from OVMA Focus Jan/Feb 2018 Vol. 37, No. 1

GR = Golden Retriever, GSD = German Shepherd, LR = Labrador Retriever, Rott = Rottweiler



A brief note on cats… Cats are much different in that their size is fairly uniform even between purebreds and mixes. I still recommend waiting until a kitten is at least 6 months old before spaying and neutering. This will give them the benefit of the growth hormones for both body weight and good bone development.

Confused yet??  There’s a lot of factors to take into account and a discussion must be had between you and your veterinarian.   Please note that there will always be disagreements and new research coming forward.

Disclaimer: Blog posts may contain some opinions which are my own and may not reflect those of any current or former employers. 

Don’t forget to follow along on Instagram @drryanllera , Facebook , or  Twitter for more pet info.