There are three potentially life threatening diseases that are commonly seen in un-spayed (pets that still have their reproductive parts) female dogs, and I had to deal with each of them last week. They are pyometria, ovarian cancer, and breast cancer. The original full-length version of this story can be found on my website:

Until they’ve had to deal with one in their own dog or cat (human women can get them also), pyometra is a disease most people probably never heard of. But it’s out there. The word pyometra comes from the Greek words ‘pyon’ meaning pus and ‘metra’ meaning womb. And that’s exactly what the disease is: a very serious, life-threatening, disease in which the uterus of the un-spayed female fills with deadly, fetid-smelling, pus.

Most people have never heard of pyometra because most owners spay their female dogs or cats. Obviously, if your pet doesn’t have a uterus (the uterus and ovaries are removed during a spay), it can’t get a uterus infection. Spaying also addresses the second disease I mentioned, ovarian cancer. These tumors can be scary! But, again, spayed dogs don’t have to worry about ovarian cancer because their ovaries are removed during the spaying surgery.

The last disease which can be greatly reduced in numbers by spaying you pets is breast cancer. Although veterinary researchers say the cancer can still happen, in the hundred or so breast cancer surgeries I’ve done, every single dog and cat was not—I’ll say it again with emphasis—NOT spayed.

So why don’t people spay their dogs or cats? The reasons are very complex and the conclusions would fill this column for the next ten years. The reasons involve multiple issues that range all the way from simply not wanting to spend the money on the surgery, to the almost sacred notion of an owner not wanting to deprive their pet of it’s God-given right to reproduce. It wears me out just thinking about it.

Pyometria is seen in dogs and cats usually over the age of four years. Most of the time owners complain of the animal having a foul (and they really do smell) and sometimes bloody vaginal discharge that comes on very suddenly. With both pyometras and ovarian cancer, sometimes the only sign will be a prolonged bloody ‘spotting’ that is likely to be confused with a regular heat. With both diseases, frequently the only complaint is the dog or cat is very lethargic and is off their feed. All of these gals will die unless attended to; and some, despite heroic efforts, sadly will die anyway from the infection or cancer which spreads to other parts of the body. Treatment always involves an emergency ovariohysterectomy (spaying), usually on a Saturday night when the vet is outta town.

Breast cancers show up as hard nodular swellings along the mammary gland chains on the bellies of cats and dogs. Observant owners usually find them early and their removal is usually curative. However, just like in human women, the cancer can spread—especially in cats. Less observant owners usually wait until a softball-sized mass bursts open on the poor pet’s belly and then it’s too late.

Thanks again.


  1. Hi Doc!
    Can you recommend any adjuvant hormonal treatment after surgery for early stage breast cancer in dogs?
    My schnautzer has had her surgery done a couple of days ago. She has got breast cancer though she had had been spayed 2 years ago – pyometra.
    Thanks for an interesting article!


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