Mammary cancer

One of the most common cancers seen in female dogs is breast cancer, or mammary cancer. It is rare but does occur in male dogs. It is usually seen in dogs older than 7 years.About half of all these tumors are malignant; and, of those, about half have spread by the time of diagnosis. One of the rare forms is highly malignant and often fatal. There are also benign tumors and those that donít fit any classification. Yet, others can be simple hyperplasia or swelling during a heat cycle.So, the only way to tell what type of breast cancer your dog has is through a biopsy and having a pathologist carefully examine the tissue on a microscope. A dog can have benign and malignant cancer at the same time! A careful exam by both your veterinarian and a microscopic exam is essential.When to spay?While early spaying has been linked to an increased risk of some cancers, this is a case where it helps dogs at high risk reduce the chances of developing a cancerous breast growth. While breast cancer has a hereditary link in humans, that has not been established in dogs. The dog breeds at highest risk are poodles, English spaniels, English setters and terriers.If dogs are spayed before their first heat, the risk for developing a mammary cancer is less than 1%. But, after the third heat the risk for development of a mammary tumor increases dramatically to 26%. Another risk factor for the development of mammary tumors is obesity.What will you see?As you would expect, you can see and feel this cancer growing. Get used to feeling your female dogís breast so you know when a lump develops. It is most common in those breasts closer to the back legs. Sometimes these also change the color of the skin to a red or purple and they may be hard to the touch. If mammary cancer has spread, the pet may have lameness due to bone involvement, breathing difficulty due to lung involvement or other generalized signs, such as weight loss and poor appetite. All of this is bad, of course. You really want to catch this one early.TreatmentThe treatment for this cancer is surgery. Most of the time, one or more glands are removed. Then, depending on how extensive the growth is, the removal of other glands or the entire chain of glands is required. This is often followed by chemotherapy, which is usually a course of IV injections every three weeks for four to five treatments.What is the outlook?The prognosis all depends on the biopsy report. Any mammary cancer that has already invaded tissue next to it is a bad sign. Tumors are usually graded as we discussed in the article on mast cell tumors. Recurrence of a grade 1 tumor is 24%, a grade 2 tumor is 68%, and a grade 3 tumor is 90%.I have seen many great dogs that had to be put to sleep because this cancer had gone on way too long without any intervention. That is practically inexcusable because this is a cancer you can see and feel. Doing an at-home physical exam is very easy and will catch most of these. Feel or ìpalpateî these glands of your female dog every week. When a cancer begins to develop, you can catch it early and get proper treatment.About 75% of the cases we see in our practice are end-stage cancer. It seems like an epidemic of this horrible disease that takes our great pets away from us. Please, if you see a lump or bump, have it seen by your veterinarian. Finally, get your pets insured. It is not expensive and will pay 80 to 90% of the veterinary bill. Especially in cases of cancer, it could be the difference between treatment and economic euthanasia.