Something we get asked about almost every day is WHEN is the right time to spay or neuter your dog? Unfortunately, it is as not as straightforward as it used to be. Historically, the simple answer to this question was 6 months of age, but as we learn more about the hormonal impact on growth, maturation and behavior this standard recommendation has evolved.
The rationale for the 6-month mark is that it will remove hormonal influence before animals are sexually mature. This will prevent heat cycles, significantly decrease the risk of breast cancer and potentially head off unwanted behaviors like marking, aggression and wandering (intact males will often leave their homes and yard in search of females and this puts them at risk for getting lost and hit by cars). These facts still hold true and make sterilization at the 6-month mark still a fair option for many animals.
The reason for the change of this, as a one size fits all recommendation for all animals, is mostly surrounding large breed dogs (for the sake of this post, we’ll call breeds that are 75-80lbs and above large). Because these dogs are not skeletally mature by the time that they are 6 months old we may be removing hormones too early as the musculoskeletal system is largely influenced by them as animals grow. The hypothesis is that by leaving the testicles and ovaries until the dog is fully grown, they will be less prone to certain orthopedic disease. This is absolutely not a fact and there is still significant research being done on the subject, however, we feel it is important that our clients be informed of the risk vs. reward profiles of both “early” (6 months old) and “mature” (18-24months) sterilization.
Below is hopefully a concise review.
| Spay | Early | Mature |
| Pros | – 95% reduction in chance of developing breast cancer
– 0% chance of accidental pregnancy – Do not have to deal with heat cycles – 0% chance of Pyometra – Less likely to bleed during surgery |
– Possible decreased risk for cruciate ligament tears
– Possible decreased risk of obesity |
| Cons | – Possible increased risk for cruciate ligament tears
– Possible increased risk of obesity |
– The more heat cycles the dog goes through the higher the risk of breast cancer
– Risk accidental pregnancy – Risk of Pyometra – Dealing with heat cycles – Dog may develop unwanted behaviors (aggression, marking) that may not resolve with sterilization – Higher risk of bleeding during surgery and a more expensive surgery |
| Neuter | Early | Mature |
| Pros | – 0% chance of accidental pregnancy
– Possibly head off unwanted behaviors (aggression, marking, wandering) |
– Possible decreased risk for cruciate ligament tears
– Possible decreased risk of obesity |
| Cons | – Possible increased risk for cruciate ligament tears
– Possible increased risk of obesity |
– Risk accidental pregnancy
– Dog may develop unwanted behaviors (aggression, marking) that may not resolve with sterilization |
A note on small dogs and cats
6 months is still very appropriate as most small animals (less than 50lbs) are very close to fully mature at this time, and waiting will only increase the risk of unwanted behaviors and disease.
At the end of the day, it is ultimately up to you, as an owner, to choose what you feel is right for you and your pet. As always, should you wish to discuss this topic further please reach out to your veterinary team.