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Tumors

  • Skin cancers are fairly common in cats, but cutaneous lymphoma is quite uncommon. Only about 3% of lymphoma cases in cats occur in the skin. There may be a linkage between feline leukemia virus (FeLV) and feline cutaneous lymphoma. Unfortunately, feline cutaneous lymphoma is considered incurable.

  • Systemic lymphoma is a very common cancer in dogs, but the cutaneous form is actually quite rare. Current statistics suggest that cutaneous lymphoma accounts for only about 5% of canine lymphoma cases.

  • The histiocyte group of cells are part of the body's immune surveillance system. Cutaneous (reactive) histiocytosis is an uncommon condition of dogs. Cutaneous, reactive histiocytosis is an immune dysfunction, mainly of young dogs and probably due to persistent antigenic stimulation by a variety of antigens (foreign proteins).

  • Cytology is the microscopic examination of cell samples. Cytology can be used to diagnose growths or masses found on the surface of the body, and also to assess bodily fluids, internal organs, and abnormal fluids that may accumulate, especially in the chest and abdomen. Cells can be collected using various methods including fine needle aspiration, skin scraping, impression smear, cotton-tipped swabs, or lavage. A biopsy is the surgical removal of a representative sample of tissue from a suspicious lesion. The most common biopsy techniques are punch biopsy, wedge biopsy, and excision biopsy. The tissue is then processed and is examined under a microscope via histopathology. Histopathology allows the veterinary pathologist to make a diagnosis, classify the tumor, and predict the course of the disease.

  • Tumors of the intestinal epithelial lining include non-cancerous polyps, benign adenomas and malignant epithelial tumors (adenocarcinomas). The polyps and adenomas may be multiple and cause local obstruction.

  • Muscle (called smooth muscle) and fibrous connective tissues form the framework (stroma) that holds other tissues together within the organs of the body. They enable these organs to contract and stretch as part of their function, for example in digestion of food.

  • Common conditions of pet rabbits include upper respiratory tract infections, internal and external parasites, dental disease, GI stasis, uterine problems, and pododermatitis. Upper respiratory infections are often caused by bacteria including Pasteurella multocida. Rabbits can become infected with various intestinal parasites, as well as external parasites such as ear and fur mites, fleas, and occasionally ticks. Rabbits’ teeth are continuously growing but chewing food, as well as chewing on wooden blocks, branches, and toys, helps them wear their teeth down at a rate equal to their growth. Occasionally, tooth or jaw trauma or disease causes misalignment of the upper and lower jaws and overgrowth of teeth results. Regular yearly check-ups enables early diagnosis and treatment of some rabbit diseases. Whenever a rabbit stops eating, for whatever reason, it is important to take her to see your veterinarian immediately for an evaluation.

  • Common conditions of pet rodents include respiratory diseases, gastrointestinal problems, dental problems, and tumors. Signs of respiratory disease in rodents include nasal and/or ocular discharge in mild infections, and wheezing, coughing, and open-mouth breathing in severe infections. Gastrointestinal disease, including diarrhea from various causes and gastrointestinal stasis is common in pet rodents. All rodents have teeth that grow continuously throughout their lives. Occasionally, these teeth grow too long and cut into the gums, causing pain, or prevent the mouth from closing properly, which often makes the pet stop eating. Just as in people, cancer is often seen in pet rodents, especially mammary (breast) tumors in rats and mice. Rodents with signs of respiratory or GI disease or evidence of a tumor should be seen by a veterinarian who can properly diagnose and treat the underlying condition.

  • Ear canal tumors can be benign or malignant. Diagnosis is typically via fine needle aspiration or tissue biopsy. The treatment of choice for ear canal tumors is surgical excision. For benign tumors, complete surgical removal is curative. With malignant tumors, a CT scan is often performed prior to surgery to determine how invasive the tumor is and enable surgical planning. Total ear canal ablation and bulla osteotomy (TECA-BO) is the most common surgical option. Radiation therapy or chemotherapy may be pursued.

  • These are tumors arising from structures within the eye. The most common intraocular tumors originate from the melanin producing cells (discussed in a separate handout).