Aside from difficulties getting pregnant and giving birth, the most common forms of reproductive disease in dogs and cats are cancers and infections – and these are quite common in intact (not spayed or neutered) pets. Breast cancer, or mammary gland tumors (MGT), are very common among middle aged to older intact female dogs and cats. About 50% of canine MGT ™s are malignant, but most feline MGT ™s are quite aggressive malignancies. Ovarian and uterine cancer are less common, but usually malignant. Dogs and cats that are spayed before every coming into heat can be almost guaranteed of never having these tumors. Prostatic cancer is almost always a dangerous malignancy in dogs, but is not very common. Testicular cancer is common, especially if a testicle is retained in the abdomen, but usually not malignant. Testicular cancer can be prevented by neutering at any time. Intact male dogs can develop prostatic hypertrophy, just like people, but the prostate is much more prone to infection. Prostatic infections can abscess and become life threatening. Neutering before the prostate hypertrophies can prevent this. Intact female dogs, especially those that have never been pregnant, are prone to a type of uterine infection called a pyometra. This is literally a bag of pus! It can make a dog severely ill, and requires surgery in most cases. These are true emergencies and delicate situations. This is another thing prevented by spaying.
You can probably tell I am a proponent of spaying and neutering. If you are not quite knowledgeable about pet reproduction and experienced with breeding, we strongly suggest altering your pets. They will be happier and likely live longer. If you have any questions about this, please call us.

by Bonnie Markoff, DVM, ABVP