Skin gland, hair follicle, and sebaceous gland tumors are more commonly found to be benign. Matrical carcionoma and sebaceous gland adenocarcinoma are rare and more aggressive forms of the disease. Regardless of the type (sweat, hair, or sebaceous) diagnosis is made by fine needle aspiration, biopsy, and/or initial surgical removal and histopathology. In the majority of cases, surgery is recommended and other treatments are unnecessary. Chemotherapy and/or radiation therapy in pets with matrical carcinomas or sebaceous gland adenocarcinomas may be recommended.
The three most common testicular tumors are seminomas, Sertoli cell tumors, and interstitial cell tumors. Though other tumor types are possible, testicular tumors as a whole are generally not aggressive and have a low metastatic rate. Pets that are cryptorchid are predisposed to the development of Sertoli cell tumors and seminomas. Hyperestogenism is possible with Sertoli cell tumors. In any cryptorchid pet, removal of both testicles should be pursued. Intraabdominal tumors in cryptorchid pets may cause lethargy, decreased appetite, and fever. Standard staging is recommended in all cases, including a rectal exam. Surgery is typically the treatment of choice and may be combined with radiation therapy or chemotherapy if metastasis is evident.
Thyroid tumors can be benign or malignant and functional or nonfunctional. In dogs, they are usually malignant and nonfunctional, whereas in cats, they are usually benign and functional. A swelling in the neck may be the only sign in a dog, however a change in bark, coughing, difficulty swallowing, facial swelling, rapid breathing, breathlessness, weight loss, and a loss of appetite are possible. In cats, the signs are related to excess thyroid hormone production (hyperthyroidism). Thyroid tumors are diagnosed with a physical examination, bloodwork, various forms of diagnostic imaging, and in dogs, a tissue biopsy. In dogs, staging is required to determine the presence of spread. A variety of treatment options are available. These include surgery, radiation, chemotherapy, and radioactive iodine therapy in dogs, and medication, radioactive iodine therapy, surgery, and dietary therapy in cats. With appropriate treatment, the prognosis for dogs and cats with thyroid tumors is good.
Transmissible venereal tumors (TVTs) arise from immune cells called histiocytes. Dogs develop this tumor from direct contact with already affected dogs, most notably during sexual contact. The tumors typically develop on the penis, prepuce, vulva, and vagina, though can develop on the skin, eyes, oral, and nasal cavities as well. The tumors are usually cauliflower-like in appearance. Clinical signs are dependent on the location, but typically the tumors ulcerate and bleed. Metastasis is rare but can affect lymph nodes and other areas of the body. Treatment may include chemotherapy or radiation therapy (for those resistant to chemotherapy). Prognosis is usually good with a high response rate to chemotherapy.
Lipomas are benign fat tumors commonly found in Budgies, some Amazon parrots, galahs and sulphur crested cockatoos. They are most often found under the skin on the sternum (breastbone or keel bone) or on the ventral abdomen, but can be anywhere on the body.
Xanthomas are discrete masses or diffuse, thickened areas of skin that are yellow-orange and dimpled in appearance. They are accumulations of fat and cholesterol and are most commonly found in cockatiels and budgies (and they are more often found in females).
While not as commonly seen as they are in dogs and cats, tumors do occur in birds. Birds of any age can develop tumors.
Malignant lymphoma (lymphosarcoma) and leukemia are among the most common malignancies seen in ferrets. Diagnosis may be made by fine needle aspiration or biopsy. For a dedicated owner with a compliant patient, surgery and/or treatment with chemotherapy is an option. Remission of lymphoma is possible with treatment in ferrets, but recurrence is common. Ferrets also commonly develop insulin-producing tumors of the pancreas that lower the ferret’s blood sugar and cause weakness, weight loss, lethargy, seizures, coma, and death. Insulinoma commonly spreads from the pancreas to the liver, so surgical removal of pancreatic insulinoma nodules may not be curative. Affected ferrets respond well for months to years to medical therapy with glucose-promoting drugs (prednisone) and anti-insulin drugs (diazoxide). Drugs suppress effects of the tumor but do not eliminate it; and ferrets on medical treatment must have their medications increased over time as the tumor grows.
Urinary tract tumors can occur anywhere along the urinary system, from the kidneys to the urethra. They are more likely to be malignant than benign. In dogs, the most common type of urinary tract tumors are bladder tumors, and of these, the most common is transitional cell carcinoma (TCC). Lymphoma and renal carcinoma are the two most common primary kidney tumors in cats and dogs, respectively, but these are relatively rare. Staging is recommended with all urinary tract tumors. With TCC, staging should include X-rays of the spine and/or hips since bone metastasis is possible. With bladder tumors, treatment is usually medical (e.g., NSAIDs) with/without chemotherapy and radiation therapy. With unilateral kidney tumors, nephrectomy is usually the treatment of choice, while with bilateral kidney tumors, chemotherapy may be considered. Treatment and prognosis always depend on the type of tumor and degree of local invasion and metastasis.
Uterine tumors are quite rare in North American pets, mainly due to routine spaying practices. Several types of tumors can arise from the tissues of the uterus. How the tumor will affect your pet is entirely dependent on the location and type of tumor. By far, uterine cancer is most commonly diagnosed by abdominal ultrasound or during a spay procedure. Full staging is recommended prior to surgery to determine if the cancer has metastasized. Treatment for solitary masses without evidence of spread typically involves ovariohysterectomy. If metastasis is present, chemotherapy should be considered, however its efficacy is not completely known. Without evidence of spread, uterine tumors carry a good prognosis.