Pet cancer awareness – take a bite out of cancer

During October – BREAST CANCER AWARENESS month – women around the world celebrate the survivors of breast cancer. We celebrate those fighting so hard to beat cancer and we remember those who fought but unfortunately lost the battle.

The point of breast cancer awareness month is to bring breast cancer to the forefront. To make people aware that women are empowered to know what to look for and how to do so. I thought I would look at breast cancer from a different view – one we haven’t thought of – that of our pets.

While breast cancer affects 1 in 8 women, did you know that dogs and cats can develop breast cancer too? More commonly referred to as mammary cancer in dogs and cats, it can easily be prevented and the risk nearly eliminated just by spaying your pet before their first heat cycle. The risk of cancer goes up substantially with each heat the dog/cat has. Female dogs and cats who have been surgically sterilised (spayed) before their first heat, which is usually around six months of age for dogs and a bit earlier for cats, are essentially free of breast (mammary) cancer.  The reason for this is that hormones play a big role in mammary cancer. Unlike human breast cancer, mammary cancer in dogs and cats has been proven to be hormone dependent. A dog’s risk of mammary tumours’ decreases with early spays surgery. If she is spayed prior to her first heat cycle, the risk of cancer is as low as 0.05%, after the first heat it goes up to 8%, and then the risk increases to 26%. Unfortunately pregnancy doesn’t protect them from mammary tumours or cancer. In dogs, 50% of the mammary tumours’ are found to be malignant while, sadly, 90% in cats

Our pets can’t follow the first and most important rule of breast cancer awareness – self-examination, but as pet owners, we can do it for them! Dogs and cats have a chain of mammary glands rather than just two breasts, so checking for lumps and bumps takes a little time.

Here’s how it works: 

Many dogs like to lay on their sides or back. Dogs normally have 10 mammary glands – two rows of five going down the length of the body, one on the left and one on the right. Find the first teat on the left and right sides. First, keep fingers flat and fan through the mammary tissue up and down the axis of the torso (head to tail) and feel for “BB gun pellets,” or bumps passing under your fingertips. Go left to right as well. Next, gently press the mammary tissue between the thumb and the index finger with middle finger. Push your fingers together with the mammary tissue between them and move the thumb across the index and middle finger in a circular motion.

Admittedly cats are a little less co-operative!

Feel for breast lumps while your cat is standing and then gently roll them over on their back so you can look at the area as well. First, while they are standing, move your hands under their belly all the way up into their armpits. Then slowly move your hands back to their groin area (where their legs attach to their body). Many overweight cats have quite a “pouch” in this area and you may need to massage the skin and fatty tissue to detect any lumps or swellings.

pet cancer
What should you be looking for:

Signs of breast cancer include the following:

• small nodules within the mammary tissue (they feel like BB gun pellets)

• larger nodules within the mammary tissue but still under the skin

• bloody discharge from the nipple

• straw colored discharge from the nipple

• pus-like discharge from the nipple

• larger, deeper growths in the mammary tissue that protrude visibly and can be seen

Other signs to look for are pain, chronic lameness, fever, a non-healing wound, weight loss, anorexia, weakness, vomiting and/or diarrhoea, coughing and difficulty breathing, sudden blindness, seizures, drinking more than normal and/or urinating larger amounts or more often.

So, what do you do if you find a lump or notice any signs and symptoms?

Veterinary Screening for Breast Cancer!

Remember you know your pet best and if you are worried take her to the vet!! A mass is checked the same way as in humans- a vet will do a FNA (fine needle aspiration) or take a small biopsy and send it to the pathologist. If your pet is one of the lucky small percentages that comes back benign then all the details are noted on her file and the tumor is monitored. If it is malignant then it will be treated. They may start with a partial or full mastectomy.

Breast Cancer Treatment 

When it comes to breast cancer treatment dogs are luckier than cats. The tumour malignancy in cats is much likely to be positive than in dogs, but it metastasises really fast to other areas of the body because of the direct nodal and blood vessel connection. This makes it easy for the cancer to spread from mammary gland to mammary gland and then to other solid organs such as lungs; liver and bone, thus making early detection vital! Once confirmed the tumour can be removed, radiated and she can be given chemo – just like a human with breast cancer. They even use similar chemo mixes. The biggest difference with the use of chemo is that it is not the first line of treatment like it is with humans.

Overall most patients out there with just lumps and bumps that are being taken off by their regular veterinarian have a very good long-term prognosis. But sadly if the cancers are left untreated, we’re talking survival times in the months, not years.


Written by Gillian Bruce.