By Jon Geller, D.V.M.
Q. We have a 7-month-old Chihuahua. Our question is about neutering. We have never neutered any dogs we had. Do we really need to? I understand that it's for their health, but are there any cons to it? Some people said it affects their growth. Is that true? I would like more info (pros and cons) before deciding to neuter.
A. You have touched on a topic that is suddenly becoming highly controversial in veterinary medicine.
If you had asked me this question more than 6 months ago, your answer would have been a resounding yes, you absolutely need to neuter your pet. This helps deter aggressive behavior, decreases risk of disease, results in a better-behaved dog, and will, most importantly, decrease the possibility of any unwanted pets due to an unplanned breeding.
Recent information has not changed that recommendation, but has qualified it. Neutering will help prevent unwanted pets, and for that reason alone, is strongly recommended. But other issues are not as clear as they used to be.
Dog behaviorists are discovering that un-neutered dogs are not necessarily more aggressive than neutered dogs, and in fact, may be more aggressive. Interestingly, neutered dogs have a higher incidence of prostate cancer than un-neutered dogs. They are generally just as healthy as neutered dogs, and possibly have lower incidence of certain injuries such as a ruptured cranial cruciate ligament in the knee. Some researchers speculate that the ligaments of neutered dogs are weaker and more prone to ruptures.
Finally, it is clear that neutered or spayed dogs have a higher incidence of obesity, possibly due to decreased activity or changes in hormonal balance.
Although the overriding consensus is still to neuter your pet, there is an interesting amount of new research that suggests there may be some downsides to doing so.
Keep in mind that millions of pets are killed every year in U.S. shelters due to overpopulation. Neutering is the best, and only effective method, of preventing this horrible tragedy. There is still controversy on what is the best age to neuter your dog, but if you do so at about 6 months of age, you can avoid the possibility of any growth abnormalities that have been discussed when neutering pets at a very young age.