Mammary Tumors in Dogs

Mammary tumors in dogs are frequently met in female dogs and are more common in females that haven't been spayed. In rare cases, mammary tumors may occur in male dogs. The tumors may be felt as small or larger lumps. The tumors may be harmless and benign or malignant and more aggressive. The early detection of a malignant mammary tumor may increase the dog's chances of survival.

Causes of Mammary Tumors

The exact causes of mammary tumors haven't been established yet, but due to the fact that the incidence of mammary tumors is higher in unsprayed dogs, the tumors may be caused by the presence of sexual hormones (estrogen or progesterone).

Female dogs are more often affected by mammary tumors than males. Typically, the tumors occur only after the age of 5.

Symptoms of Mammary Tumors

The mammary tumors may be felt as swellings or lumps on the dog's chest. You should always check for lumps and nodules when grooming your pet; however, make sure to palpate the mammary glands gently, so as not to cause tissue damage. Most typically, mammary tumors will be present on the 4th and the 5th mammary gland of the dog. However, the other glands may feature tumors too.

The mammary tumors may grow rapidly (they may double in just 30 days).

The dog may present additional symptoms such as lethargy, bleeding or ulceration of the tumor and behavior changes.

Detecting Mammary Tumors

There are 2 main types of mammary tumors: benign and malignant. A biopsy and a histopathology test can establish clearly the type of mammary tumor affecting your pet.

If the tumor is found malignant, the vet may perform several other tests including x-rays and blood tests to determine if the cancer has developed and affected other organs (most commonly the lymph nodes or the lungs).

Treatment Options

Benign tumors should be left alone, as they won't pose a health danger and they are less likely to develop. However, these should be monitored.

Malignant tumors require treatment; if possible, the cancerous tissues should be surgically removed. If the tumor is removed, there are chances that the cancer will not reoccur; the vet needs to remove the surrounding cells around the tumor to ensure that all cancerous cells are gone. Chemotherapy may also be recommended to keep the cancerous cells at bay.

However, if the cancer has spread to larger areas of the dog's body, the surgery may not be an effective treatment option. Chemotherapy and radiation therapy will be the only remaining options. Typically, at this point, a full recovery is no longer possible. However, with medication, the dog's life expectancy and quality can be improved.

Prevention of Mammary Tumors

Dogs spayed or neutered during the first year of their lives have minimal chances of developing mammary tumors. Ideally, the spaying must be performed just before the first heat cycle. Consult your vet to determine the best time for spaying or neutering your pet.