Canine mammary cancer (CMC) is a cancer of the mammary glands in dogs, most commonly found in middle-aged dogs. These cancers are rare and account for about 1% of all canine cancers. The good news is that CMC is a highly treatable disease, and effective treatments are available.
CMC has a poor prognosis and is generally fatal. However, if your dog has been diagnosed with CMC, there is hope. With treatment, a large percentage of dogs with CMC can live long, healthy lives. Read on to learn more about canine mammary cancer, how it’s diagnosed, and how you can help your dog during treatment.
This article is intended for pet owners who are already familiar with the basics of canine cancer and canine cancer treatment options. If you’re looking for more information on canine cancer, we recommend our comprehensive guide to canine cancer.
What is Canine Mammary Cancer?
Cancer is a disease in which normal cells grow abnormally and invade other tissues in the body. One type of canine cancer, mammary cancer, causes female dogs to develop mammary glands that are abnormal or do not function properly. This can happen on one or both sides of the chest.
Mammary glands are present in all female dogs. The purpose of the mammary glands is to produce milk for nursing pups. When a dog develops cancerous mammary glands, they can become overgrown and interfere with the normal function of the female dog’s mammary glands.
The cancerous mammary glands can become irritated by milk production, resulting in mastitis. Mastitis is an inflammation of the mammary glands, which is caused by an overgrowth of breast tissue in the female dog.
Alternatively, the cancerous mammary glands can become engorged with milk, causing the dog to develop milk fever. If a dog develops milk fever, it usually isn’t serious and the milk should be removed from the dog via milking.
In addition to symptoms caused by mammary gland overgrowth and irritation, cancer can also cause pain and physical abnormalities. If a dog has cancer in the mammary gland, it can affect the symmetry between the two sides of the chest.
A mammary abscess rupture can spread the cancerous tissue around the body. However, the overall prognosis for most dogs diagnosed with CMC is generally very good.
Symptoms of Canine Mammary Cancer
Symptoms depend on where in the chest the cancer is located. Early-stage cancers that have not spread to other tissues or organs are found on the mammary glands and are typically painless. Late-stage cancers are found in the surrounding tissues and are associated with pain, swelling and difficulty breathing.
The most common symptom of early-stage disease is milk fever. This is caused by an overgrowth of milk-producing cells on the mammary gland. Milk fever usually lasts for less than 24 hours and the dog will not show any signs of an abscess or infection.
If a dog is diagnosed with mammary cancer that has not spread to other tissues or organs, it will be allowed to nurse the puppies. The puppy will be taken for regular mammograms to monitor for any signs of cancer.
Some dogs will not show any signs of CMC when they are first diagnosed. They will be monitored regularly and will require additional blood tests to detect disease progression.
Mammary cancer that has metastasized to other organs can be symptomless. In these cases, a dog will have difficulty breathing, have a reduced appetite and be in constant pain.
What Causes Canine Mammary Cancer?
The most common cause of this cancer is a genetic predisposition. This means that certain breeds are more likely than other breeds to develop the disease. Currently, researchers are looking into environmental factors that may be linked to canine mammary cancer.
Some researchers believe that exposure to certain irritants, such as certain chemicals and toxins, may cause the cancer. The exact cause of CMC is unknown, but can be attributed to a number of factors.
How Is Canine Mammary Cancer Diagnosed?
A mammary ultrasound is the most common diagnostic test used to detect cancer in the breast. The dog is placed on a short leash and a technician uses a handheld ultrasound device to view the breast.
The technician then reviews the images with the owner, who can see if the cells in the breast are abnormal or if there is any abnormal structure in the breast.
Other diagnostic tests for mammary cancer include:
Blood tests that test for circulating tumor cells (CTCs) and the protein carcinoembryonic antigen (CEA). The results from these tests can help determine if the cancer has spread to other organs and can be helpful in staging the disease.
Canine Mammary Cancer Treatment Options
Treating CMC is a challenge because the disease is rare and has few treatment options. If the disease is localized, surgical removal of the mastectomy, in which a section of the breast is removed, is usually curative.
Surgical removal can be curative if the cancer is localized to the breast. However, when the cancer has metastasized, there is no treatment that will remove all of the cancerous cells.
The Bottom Line
Canine mammary cancer is rare in dogs, but this cancer is treatable if diagnosed early. If your dog is diagnosed with CMC, there is hope. With treatment, a large percentage of dogs with this disease can live long, healthy lives.
If your dog develops symptoms of CMC, you should take them to the veterinarian immediately. If the cancer has spread to other organs, the treatment options are limited, but surgery can be curative. If your dog shows signs of CMC, you should take them to a veterinarian as soon as possible.
Your dog’s best chance for a healthy life is to be diagnosed with CMC as early as possible. CMC is a rare cancer, and it’s important to catch it as early as possible to make sure that the cancer is caught in its earliest stages. CMC is most often found in middle-aged dogs, so if your dog is exhibiting any signs of breast swelling, you should take them to a veterinarian as soon as possible.