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Cats + Cancer & Tumors

  • Radiation is a type of energy produced naturally by the sun, earth, and rocks and artificially by machines. Although several types of tumors can be treated with radiation therapy alone (e.g., nasal tumors, brain tumors, and certain types of lymphoma), radiation therapy is most commonly used to destroy or limit the growth of cancer cells left behind (i.e., microscopic disease) after a tumor has been surgically removed. Side effects depend on the type and location of the tumor and its surrounding tissues.

  • Salivary gland tumors are rare in dogs and cats. The mandibular and parotid glands are most commonly affected. Signs include swelling of the upper neck or ear base, halitosis, anorexia, weight loss, difficulty eating, pain, and lethargy. The treatment of choice is usually surgical excision. If complete excision is not possible, adjunct radiation therapy may be pursued.

  • Soft tissue sarcomas are a broad category of tumors that can develop over the chest, back, side, legs, and facial tissues of your pet. The clinical signs depend on where the tumor is located and the tissues that are affected. Often, pets have a noticeable mass that is growing in size. One of the biggest concerns with soft tissue sarcomas is their ability to invade the local surrounding tissues. The most commonly pursued treatment is surgery. Chemotherapy is not usually pursued as a primary treatment unless surgery or radiation are not options for your pet based on the tumor size or location.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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.

  • 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. This handout discusses uterine tumors in dogs and cats. The various types of these tumors, along with the clinical signs, diagnosis, treatment, and prevention of this condition are outlined.

  • Vascular tumors of the skin develop from the blood vessels of the skin. These tumors may arise anywhere on the body and appear as a firm and raised lump on or under the skin. Hemangiomas may ulcerate and bleed; hemangiosarcomas may bleed into the surrounding tissues. This type of tumor is typically diagnosed via a tissue biopsy or surgical removal of the entire tumor. Surgery is the recommended treatment for vascular tumors of the skin.