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Cancer & Tumors

  • Lipomas are common, usually harmless, tumors of fat that usually show up as a lump under the skin in middle-aged to older animals. Some pets will develop these tumors in their armpit region, between their legs, or around the neck, which can cause discomfort and/or lameness. You may see your pet exhibit an irregular gait, and/or reluctance to stand, walk upstairs, or go for their normal walks. This handout reviews the diagnosis, treatment, and prognosis of lipomas.

  • An adrenal cortex tumor is an abnormal growth of cells in the adrenal cortex. These tumors result in overproduction of cortisol and can be malignant (cancerous) or benign. In both cases, an adrenal cortex tumor can cause Cushing's disease in dogs. Malignant tumors can metastasize to other organs, including the kidneys, lymph nodes, and thyroid gland. The sooner a diagnosis and treatment plan can be determined, the better the outcome for your pet.

  • The adrenal medulla is responsible for producing hormones such as epinephrine, norepinephrine, and dopamine. An adrenal medulla tumor is the result of abnormal, uncontrolled growth of the cells that produce these hormones. These tumors may go undetected for a long time and clinical signs may be subtle. These signs could include weakness, excessive panting and restlessness, newly noted anxiety, and an increase in drinking and urination. The biggest concern with these tumors is their ability to continue to grow and invade local tissues, which can make surgical removal difficult or impossible.

  • Anal sac tumors grow quickly and have a moderate risk of spreading to other parts of the body. Depending on the tumor’s size, your pet could develop signs of straining to defecate or produce thin ribbon-like stool. An increased calcium level in the blood is consistent with anal sac tumors, which can cause other signs and result in kidney failure. The best and most well-described local treatment for the primary tumor is surgery. Radiation and chemotherapy may be considered if there is evidence of spread.

  • Basal cell tumors are a common type of skin tumor arising from cells in the deeper layers of the skin. They vary in size, from a few centimeters to inches in diameter, and most commonly appear as single, firm, hairless, raised masses in the skin, often on the head, neck, or shoulders. Most of these tumors are benign but removal may still be considered to prevent trauma or secondary infection. Surgical removal is curative in most cases.

  • Benign fibrous skin tumors can go by many names and in many cases don't need treatment. Surgical excision can be curative unless certain types are due to an underlying tumor elsewhere. The main focus in many cases is addressing underlying allergies or sources of pressure. To adequately diagnose these tumors, a biopsy and histopathology are usually necessary.

  • Mammary tumors develop due to abnormal reproduction of the cells that make up the breast tissue. They can be benign or malignant. The incidence of these tumors is related to hormone status, specifically whether a dog is intact or has had an ovariohysterectomy, age, and breed. Because dogs can have both benign and malignant tumors at the same time, surgical removal and histopathology of all tumors are very important.

  • Rabbits and guinea pigs commonly present symptoms related to the urinary system. At home, the owner may notice urine collecting in the hair on the inside of the rear legs, a more pungent smell to the urine, the pet straining to urinate, or hematuria (bloody urine). After a proper physical exam and a thorough palpation of the urinary bladder, the veterinarian may identify bladder stones (a firm, oval hard mass in the bladder) or "bladder sludge" in rabbits (a bladder filled with a grainy, sand-like material). X-rays of the abdomen allow the veterinarian to identify the type of bladder disease and/or the number of stones.

  • A chemodectoma is a type of tumor made up of chemoreceptor cells. Chemoreceptor cells detect chemical changes in the body and respond by regulating chemical or physical processes. These tumors are most often seen along one of the carotid arteries and the aorta. Brachycephalic breeds are more predisposed to these types of tumors, though they may occur in any dog breed. These tumors are usually locally aggressive, however, there are rare cases of metastasis to other organs, including the lungs, lymph nodes, and bone.

  • Chemotherapy is the therapeutic use of chemical agents to destroy or inhibit the growth and division of cancer cells. Usually, chemotherapy is used when tumors are widespread or when there is significant or immediate risk of spread from the primary location. It is often used following the surgical removal of tumors. In some cases, chemotherapy is started prior to surgery. The side effects of chemotherapy are related to the effects of chemotherapy on normal -as well as cancerous- cells. The principal goal of cancer care in pets is to provide cancer control without reducing quality of life.