Mammary Tumor in Dogs

MAMMARY TUMOR

Mammary tumor is one of the most commonly occurring tumor in dogs. The dog is by far the most frequently affected domestic species. Almost 50 % of mammary tumors are malignant in dogs. Dogs get this tumor far more common than women(prevalence of almost 3 times that in women).

Mammary tumor is also seen in male dogs, although extremely rare. These tumors are commonly observed in intact bitches. Spaying before the first heat reduces the risk of mammary neoplasia to 0.5% of the risk in intact bitches.  However, dogs spayed after the attainment of maturity have been considered to have the same risk as that of an intact female.

A tumor can be suspected if you feel or find any lump on its mammary glands. The rate of growth of the mass usually helps in determining the prognosis. 

Your vet might ask for 3 radiographs ( X rays) to be taken. Two lateral views- left and right (animal lying on its sides) and a ventro-dorsal view( with the animal lying on its back). Additionally, a fine needle aspirate of the mass may also be taken to differentiate between inflammatory and neoplastic lesions; this, however is not conclusive. Definitive diagnosis is made by histopathological examination of the mass and is important to know the type of tumor and prognosis.

Treatment is usually through surgical removal of the mass. Depending on the type of tumor, lymph node involvement, glands involved etc, your surgeon decides the surgery procedure. Removal of the tumor(lump) alone, removing only the affected mammary glands, removing all the glands with its associated lymphatic drainage etc are the available options. Recent research suggests advantages of simper procedures over the more complex ones in terms of survivability and prognosis. 

Chemotherapy has not yet proved beneficial in treating mammary tumors, neither is radiation therapy.

Prognosis of dogs with mammary gland tumors varies. Usually metastasis takes place to the lungs and they have bad prognosis. Most mammary tumors that are fatal cause death within one year. 

Note the lump on the gland

 This 7 year old, non descript, intact female dog was presented to the Humane Animal Society Clinics for evaluation of a lump in her mammary gland. A fine needle aspirate was obtained and results suggested it to be neoplastic. The tumor invaded two glands, so it was decided to surgically excise both the affected mammary glands.

After preparation of the surgical site

2 weeks after surgical excision of the affected glands