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Lymphatic tumors are rare in pets. Lymphangiomas are benign and lymphangiosarcomas are malignant and have a moderate-to-high metastatic potential. Patients with lymphatic tumors typically have severe edema or cavity effusions because of lymphatic obstruction and leakage. These types of tumors occur more frequently in young dogs and cats. Treatment usually involves surgical excision and chemotherapy may be used as a follow-up treatment in the case of lymphangiosarcomas.
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Lymphoma is a cancer of the lymphocytes. Lymphocytes are cells that are involved in the immune system. Feline lymphoma most commonly affects the intestines; therefore, clinical signs of lymphoma are often similar to other intestinal diseases. Diagnosing lymphoma requires finding cancerous cells on microscopic examination. This cancer cannot be prevented, but the likelihood of a cat developing lymphoma can be decreased by preventing feline leukemia virus infection.
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Lymphoma is a cancer of the lymph nodes and lymphatic system. This cancer may be localized to one particular region, or may spread throughout the entire body. Lymphoma is a relatively common cancer, accounting for 15-20% of new cancer diagnoses in dogs. The prognosis for lymphoma varies, depending on various characteristics that can only be determined by specialized testing.
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The most common forms of cutaneous lymphoma are epitheliotropic lymphoma and dermal lymphoma. No specific risk factors or causes have been identified in the development of cutaneous lymphoma. Generally, cutaneous lymphoma can appear as various-sized irritated, ulcerated, or infected patches anywhere on the skin, including the gums, nose, or lip margins. These areas may become ulcerated and bleed, or become crusted. Secondary infections are possible. By far, the most common treatment for cutaneous lymphoma is chemotherapy. Unfortunately, the response to treatment, although initially encouraging, is typically short-lived, with gradual return of the tumors.
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There are several different types of malignant mammary tumors, with carcinomas being the most common. Carcinomas arise from epithelial (skin) cells, tubules of the mammary glands, or other cells found in the mammary chain. The size of the masses and their appearance may vary, but they are usually firm and nodular. Occasionally, the skin over the mass may ulcerate (open) and bleed, and the affected area may feel warm to the touch and become painful. Detecting and treating these tumors when they are small, and before spread has occurred, will provide your dog with the best chance for long-term control.
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A mammary tumor develops because of abnormal replication of the cells that make up the breast tissue. In cats, most mammary tumors (80-96%) are malignant. Sexually intact cats have a seven-fold increased risk for mammary tumors compared to spayed cats. Detecting and treating these tumors when they are small, and prior to metastasis, provides your cat with the best chance of long-term control. Surgery is by far the best treatment and, given the high metastatic rate in these tumors, chemotherapy is typically pursued afterward.
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Mast cells are a type of white blood cell that plays a large role in allergic response through degranulation. Mast cell tumors (MCT) can occur in the skin, spleen, or gastrointestinal tract of cats. Their cause is unknown; however, many affected cats show a genetic mutation in the KIT protein involved in replication and cell division. Cutaneous MCTs most often appear as hard pale/white plaques or nodules, often around the head and they may be itchy. Splenic MCTs cause decreased appetite, weight loss, and vomiting. Intestinal MCTs may cause GI upset and bloody stools, and a mass may be palpable. Diagnosis is typically achieved via fine needle aspirate although histopathology can be used. Treatment usually requires surgical removal of the masses or the spleen. Sometimes, chemotherapy or radiation is needed.
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Mast cell tumors are most common in the skin of dogs and may appear red, ulcerated, or swollen. They can be itchy and can fluctuate in size. Tumors can range from lower-grade, with minimal spread, to higher-grade, with a high risk of local invasion. Treatment usually involves surgical removal and may require supportive treatment including chemotherapy, radiation therapy, and therapy to target the mutation that instigated the tumor.
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Melanomas are cancerous growths of the cells responsible for pigmentation of the skin. They can develop anywhere on the body but those on the toes carry the highest chance for malignancy. They may be painful and you may notice your pet licking at the affected area. Surgery is often the treatment of choice and may be followed up with radiation or chemotherapy.
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Many herding breeds (most commonly Collies and Australian Shepherds) have a mutation at the MDR1 gene that makes them more sensitive to the negative effects of certain medications. These drugs include several antiparasitic agents (when given at high doses), the antidiarrheal agent loperamide (Imodium®), and several anticancer drugs. The effects of the mutation vary in severity, depending on whether the dog carries one or two copies of the mutation. There is a cheek swab or a commercially-available test that assesses blood samples for the presence of the MDR1 mutation.
