Educational Articles
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Stomach tumors are uncommon in dogs and cats. There are many kinds, including leiomyosarcomas, lymphomas, adenocarcinomas, mast cell tumors, fibrosarcomas, plasmacytomas, gastrointestinal stromal tumors (GISTs), and carcinoids (all malignant); and leiomyomas, adenomatous polyps, and adenomas (benign). Most tumors are malignant. Stomach tumors are more prevalent in older animals, males, and certain breeds. The signs of stomach tumors include chronic vomiting, inappetence, lethargy, and weight loss. Sometimes tumor ulceration will cause anemia. Paraneoplastic syndromes are possible with the muscle tumors. Stomach tumors may be diagnosed with imaging, endoscopy, or surgery, with a biopsy. Treatment may involve surgery, chemotherapy, or radiation therapy.
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Skin gland, hair follicle, and sebaceous gland tumors are often benign. Matrical carcinoma 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 surgical removal and histopathology. Further treatment is reviewed.
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Testicular tumors are generally not aggressive and have a low metastatic rate. Pets with undescended testicles (cryptorchid) are predisposed to the development of certain testicular tumors. 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.
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Thyroid tumors can be benign or malignant and functional or non-functional. In dogs, they are usually malignant and non-functional, 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.
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Transmissible venereal tumors (TVTs), often found in genital areas, are spread through contact with other dogs, most often sexual contact. The tumors are usually cauliflower-like in appearance. Diagnosis and treatment is discussed.
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Tumors are cancerous growths. They may be found on the surface of a bird's body or in the internal organs. Veterinary examination of any growth or lump is highly advised as tumors may grow rapidly or spread.
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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.
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Lipomas are fatty tumors that affect a variety of pet birds. These are typically benign fatty growths found under the skin. It is classically considered to have both a nutritional and genetic factor for development.
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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).
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Tumors of the urinary tract may present anywhere from the kidneys to the tip of the urethra. Tumors of the bladder are most common in the dog whereas tumors involving the kidneys are more prevalent in cats. Unfortunately, many tumors of the urinary tract are malignant and treatment options may be limited. Surgery is possible in select cases. Medical treatment may be beneficial in cases where surgery is not possible.