Mammary Tumors in Dogs
General Information
Mammary tumors are the most common tumor in female dogs. Both malignant (cancerous) and benign tumors can occur. The cause of these tumors is unknown, but there is a hormonal influence on tumor development and rate of growth.
Treatments for mammary tumors include surgery, irradiation and chemotherapy. The type of treatment used is determined by the kind of tumor and the degree to which it has spread.
Understanding Your Pet's Medical Diagnosis
What are mammary gland tumors in dogs?
Mammary gland tumors in dogs are tumors that affect one or multiple mammary glands. About half of the dogs will have multiple tumors. Mammary gland tumors may be benign or cancerous (malignant). Benign tumors do not extend into other tissues (that is, they are relatively non-invasive) and they do not spread into other parts of the body (that is, they do not metastasize). Cancerous (malignant) tumors do extend into other tissues (that is, they are invasive) and they do spread into other parts of the body (that is, they do metastasize). Approximately 50% of mammary tumors in dogs are malignant.
What causes mammary gland tumors in dogs?
The actual cause of mammary gland tumors in dogs is not known; however, it is thought that tumors may be associated with hormonal changes. The risk of this disease is greater in intact female dogs. Dogs that are spayed before their first heat cycle (estrus) have 0.5% risk of developing this disease. This risk increases with the number of heat cycles. A dog spayed after its second heat has a 26% risk of developing mammary tumors.
What are the signs of mammary gland tumors in dogs?
The common clinical signs associated with mammary gland tumors in dogs include single or multiple masses in the mammary area. The tumors may be ulcerated.
How are mammary gland tumors diagnosed in dogs?
Mammary gland tumors are diagnosed in dogs upon physical examination. Benign tumors usually are unattached to the surrounding structures and freely movable. Tumors that are attached or "fixed" to the body wall or adherent to the skin are more likely to be cancerous. Chest radiographs (X-rays) may be performed to determine if the tumors have spread to the lungs (lung metastasis).
How are mammary gland tumors treated in dogs?
Surgical removal of the tumor, either by local tumor excision (lumpectomy) or by the removal of the entire mammary gland (mastectomy), is the treatment of choice. Chemotherapy also may be effective in some cases. However, due to the toxic side effects associated with chemotherapy, regular re-check examinations and blood work should be performed for the duration of the therapy. Pet guardians should be encouraged to spay their female dogs before the first heat to decrease the likelihood of mammary gland tumors.
What is the prognosis for dogs with mammary gland tumors?
The prognosis (outcome) for dogs with mammary gland tumors is variable, depending on the nature of the tumor and the presence of metastasis.
Important Points in Treatment
1. Surgical removal of these tumors is the treatment of choice. A sample of the tissue will be submitted to a pathologist to determine whether the growth is cancerous.
2. Various blood tests and radiographs (x-rays) may be necessary to determine if the tumor has spread to other parts of the body.
3. Give all medication as directed. Call the doctor if you cannot give the medication.
4. Diet: Follow the instructions checked.
____Feed the normal diet.
____A special diet is required. Feed as follows:
5. Activity: Follow the instructions checked.
____Allow normal activity.
____Restrict activity as follows:
6. Surgical patients: Inspect the incision daily. Report any abnormalities
to the doctor.
7. Special instructions:
Notify the Doctor if Any of the Following Occur:
* Your pet is reluctant to eat or drink, or seems depressed.
* Vomiting occurs and persists after the first few hours home.
* Your pet removes the sutures or otherwise damages the incision.
* There is swelling or drainage from the incision.
* There is a new enlargement of the mammary glands.
The information on this page was obtained from the site www.vetmedcenter.com