What You Need to Know About Breast Cancer in Dogs

golden retriever at the vet

Breast cancer affects humans, but did you know it can also affect your dog? Breast cancer in dogs goes by a few other names like canine breast cancer and mammary cancer. No matter what it’s called, the idea of someone you love developing cancer is a scary one. As with humans, education, check-ups, and preventive measures can go a long way in prevention, early detection, and treatment. Here’s what you need to know about breast cancer in dogs:

How Common is Breast Cancer in Dogs?

Breast cancer in dogs is one of the most common cancers that affect canines. It affects female dogs far more often than male dogs. Breast cancer occurs in approximately 25% of unspayed female dogs. The onset of canine breast cancer usually occurs in dogs that are between 5 and 10 years old.

Of the dogs affected, there is an even split between benign and malignant mammary tumors – 50% tend to be benign while 50% tend to be malignant. Benign tumors do not generally pose a threat as they are an internal growth that will not spread to the surrounding tissue. With malignant mammary tumors, they do spread to the surrounding tissue, but can be successfully removed with surgery if caught early enough.

Although this type of canine cancer is more common in female dogs, male dogs also have mammary glands and run a very small chance of developing breast cancer. Breast cancer in male dogs is extremely rare. Because it is rare, it is generally malignant and metastisizing by the time it is discovered. So, although it is rare, early detection is especially important for cases of breast cancer in male dogs.

Symptoms and Signs of Breast Cancer in Dogs

In most cases, breast cancer in dogs was discovered during routine physical exams at the vet, which only serves to emphasize the importance of regular check-ups and vet visits. It’s also a good idea to keep an eye on your dog in between vet visits. A great time to give your dog a quick check is when you are grooming them. Here are some symptoms and signs of breast cancer to look out for:

Lumps and Swelling

When looking over your dog for signs of mammary tumors, you want to look and feel around for single or multiple lumps. These will appear as firm lumps, swellings, nodules, or masses and will be confined to around the nipple area. They could be like ulcers or abscesses, or not. They may be freely movable under the skin or more fixed. Usually, if a lump is freely movable, it’s more likely to be benign. On the other hand, if it seems fixed to the muscle or skin and is irregularly shaped, it tends to be more likely to be malignant.

You may also find swollen lymph nodes under your dog’s armpits or around the groin area. There are other health conditions that can cause enlarged lymph nodes and swelling in other areas. So, if you find these symptoms, it’s important to visit your veterinarian and get things checked out before diagnosing on your own.

Pain and Abnormal Secretion

A few other potential signs and symptoms of breast cancer in dogs are pain in the mammary glands and abnormal secretions from the nipple. As you are giving your dog a once-over, rub their belly and gently press on their mammary glands. If they flinch away, yelp, whine, or even growl or snap at you, they’re letting you know that it hurts. Take note of where it seems the pain originated and make an appointment with your vet to get it checked out.

As odd as it may seem, you will also want to check your dog’s nipples. If an abnormal secretion, like pus, a yellow discharge, or a bloody discharge, comes out of one or more of them when you press on them, that’s a sign that something is going on. It may or may not be breast cancer, but you will still want to take your dog to the vet for a check-up.

Odd Issues in Other Areas

As you’re checking over your dog, keep an eye out for anything odd in other areas too. Lameness in limbs, respiratory issues, and any signs of systemic illness, like weakness, weight loss, loss of appetite, lethargy, and more, should be noted and followed up with an appointment with your vet. These symptoms can be signs that cancer has spread, but may also be an indication of something else. When your dog is not feeling well, there are several symptoms that overlap with many health conditions, so you want to make sure you plan to visit the vet if you see anything odd.

Treatment of Canine Breast Cancer

If your dog does develop canine breast cancer, there are treatment options available. As mentioned previously, about half of the tumors are benign and half are malignant. If your dog’s tumors are benign, you don’t usually need to worry about treatment as they generally do not pose a threat to your dog’s health.

With malignant tumors, surgery is currently the best treatment option. Usually, the tumor is removed with a small, local surgery. Depending on whether the cancer has metastasized or shown signs of spreading, the entire mammary gland will be removed in addition to the lymph nodes to prevent further spread. There may also be a recommendation to follow up with radiation or chemotherapy.

How to Prevent Breast Cancer in Dogs?

Because breast cancer affects unspayed females the most, one of the best ways to prevent it is to spay female dogs. If a female dog is spayed before going into their first heat, the risk of developing breast cancer drops from 25% to .05%. If they have had one heat cycle, but are spayed before their second heat, the risk drops from 25% to 8%.

Even spaying your female dog by the time they are 1 or 2 years old helps reduce their risk of developing breast cancer. Usually, the older the dog is when they are spayed, or if they remain unspayed, they are at a higher risk. Aside from spaying, regular check-ups and early detection are your best weapons. They may not help you prevent breast cancer, but they will certainly help give your dog the best chance possible to overcome it.

There is a small chance that spaying your female dog after they have had a litter could cause them to become incontinent. This “bed-wetting” reportedly occurs in around 20% of mated females that have been spayed. There could be other things happening in these cases, like the dogs are older or have another medical condition that causes incontinence, but there is the potential that the loss of estrogen from being spayed causes the incontinence. Should it occur, there is a daily oral medication available to help manage it.

Thinking about something happening to your dog or your dog getting sick is never a happy or fun time. But, staying educated, keeping regular check-ups with your vet, and implementing preventive measures can help keep your dog healthy and also ensure that you catch anything that may be happening early enough to help your pup overcome it.