Ask the vet: What's the best policy on neutering?

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April 2, 2013
By: Dr. Teresa Hershey
Dr. Teresa Hershey

Q: I have a new, 8 week old, male, yellow lab puppy.  When is the best time to have him neutered?

— Amy O.

A: Dear Amy,

What used to be a simple answer to this question, has now evolved into complicated discussion that takes the dog’s breed, age, sex and temperament into consideration. 

Neutering is the common name for orchiectomy (removing the testicles) and spaying is the common name for ovariohysterectomy (removing the ovaries and uterus) or ovariectomy (removing just the ovaries). 

Spaying and neutering is obviously great for population control. Shelters and rescue groups typically require that cats and dogs be altered before being adopted to ensure that they can no longer reproduce. It is very common for puppies and kittens to be altered as early as 6 weeks of age prior to adoption. 

When animals are growing, the bone growth takes place from a site at the end of the bones called the growth plate. Sex hormones, like estrogen and testosterone, close the growth plates. If a puppy is spayed or neutered before their bones are done growing, the closure of the growth plates is delayed, sometimes by several months. The result of this is that the dog will get a little taller. We also know that dogs that are spayed or neutered, are more prone to tearing the anterior cruciate ligament (ACL) in their knees. It is not known if asymmetrical growth plate closure, or other factors, like the tendency to become overweight after spaying or neutering, is the cause of this predisposition to ACL injury. In an ideal world, dogs wouldn’t be spayed or neutered until their skeleton is fully developed.  But, there are many other factors that need to be considered when deciding when to spay or neuter your dog.

Female dogs that are spayed before their first heat have an almost zero percent chance of developing mammary (breast) cancer. The more heats she goes through, the more likely she is to develop this form of cancer. Intact females that have gone through multiple heats are seven times more likely to develop mammary cancer than females spayed early on.  In fact, her risk goes up by 8 percent if she goes through even one heat.  Because of this, most veterinarians recommend that female dogs be spayed before their first heat. Each dog and breed is different as to when they come into heat the first time.  Some females can come into heat as early as 5 months of age. For other dogs, it can be as late as 18 months. On average, it’s at about 7-9 months of age that females go through their first heat. Most veterinarians will recommend spaying a female dog, regardless of size at about 6-7 months of age. 

Your dog’s behavior also plays a major factor in when he or she should be spayed or neutered. Undesirable behaviors such as marking can start to present themselves at 6-9 months of age, when your puppy starts to go through sexual maturity. If your pet is starting to exhibit behavioral problems, neutering early is definitely a better option. 

Dr. Teresa Hershey is a veterinarian at Westgate Pet Clinic in Linden Hills. Email her your pet questions at drhershey@westgatepetclinicmn.com.