Lipomas are benign tumors of fat seen in middle-aged to older animals. Sometimes these tumors grow in between muscle layers are called infiltrative lipomas. Lipomas are benign and do not typically behave aggressively. Liposarcomas are the malignant form of the disease. These tumors are usually diagnosed by a fine needle aspiration, though biopsy or advanced diagnostic imaging may be required before surgery. Surgery is the best course of action for pets with lipomas and fat-based tumors.
The adrenal glands are responsible for hormone production. Overproduction of these hormones typically manifests as Cushing’s disease (hyperadrenocorticism). Typically, these tumors are benign in nature and can be treated medically, though malignant tumors (e.g., carcinomas/adenocarcinomas) are possible. In these cases, surgical excision is generally required. The prognosis for patients with adrenal tumors is generally good if surgical removal is complete.
The adrenal medulla is responsible for producing hormones such as epinephrine and norepinephrine. Dysregulated replication of the chromaffin cells of the adrenal medulla lead to development of a pheochromocytoma. These tumors produce excess hormone that leads to episodes of hypertension and tachycardia. Early detection via abdominal ultrasound is imperative for surgical success. CT scan prior to surgery is recommended as these tumors have the potential for vascular invasion leading to post-operative complications. Staging is recommended given that approximately 40% of patients will have evidence of spread at time of diagnosis.
Anal glands are located on either side of the anus and normally produce secretions that are pushed when feces is evacuated from the rectum. An anal sac tumor is a tumor of made up of cells originating from the glands of the anal sac. These tumors can spread and therefore staging is recommended prior to surgery. To diagnose these tumors, a fine needle aspirate can be placed from the outside and into the anal sac to retrieve cells. After surgery, chemotherapy may be considered. Radiation therapy has also been considered as a primary or secondary treatment option.
A basal cell tumor is an abnormal growth/mass resulting from the uncontrolled division of basal cells. There is no known reason for the development of these tumors in cats and dogs; however, certain breeds of dogs and cats are more likely to develop basal cell tumors, including Wirehaired Pointing Griffons, Kerry Blue and Wheaten Terriers, Cocker Spaniels, Poodles, and Siamese Cats. Fine needle aspiration may aid to guide the diagnosis, but definitive diagnoses are typically made via surgical removal and histopathology. There are few reports of local recurrence and metastasis (spread) does not appear to occur. With adequate surgical removal, long-term control is likely.
Fibrous tumors, including hamartomas, are a group of benign tumors arising from fibrous and fibrous-like tissues. Nodular dermatofibrosis can be secondary to (or a consequence of) tumors in the kidney or uterus. Fibrous tumors can develop as the result of underlying, repeated trauma (e.g., pressure on the elbows when lying on hard surfaces and self-trauma with skin allergies). Therefore, once a diagnosis has been made, determining and understanding the underlying cause is important.
Mammary tumors in dogs are not very common in North America due to routine spay procedures. Hormones play a role in tumor development in dogs. Dogs spayed before their first heat have only a 0.5% chance of developing mammary tumors. Certain breeds appear to be predisposed to developing mammary tumors. Benign tumors are typically not painful and usually are discovered during routine examination by your veterinarian. Surgery is typically the treatment of choice.
Chemodectomas are tumors of chemoreceptor cells located in several locations in the body, with the most common areas being the carotid artery and aorta. These tumors are considered rare in dogs, and especially rare in the cat. Brachycephalic breeds may be predisposed to developing these types of tumors. The most common clinical signs associated with aortic tumors include weakness/wobbliness, lethargy, collapse, exercise intolerance, increased respiratory rate and effort, fluid within the sac around the heart, cough, vomiting, and sudden death. The most common signs associated with carotid artery tumor are swelling in the neck region, regurgitation, lethargy, difficulty breathing, weakness, and collapse. Advanced imaging is typically used to diagnose these tumors. Surgery is the most common treatment option and pericardectomy may be recommended.
Chemotherapy is the therapeutic use of chemical agents to destroy, or inhibit the growth and division of cancer cells. Chemotherapy is usually 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. Different protocols are used depending on the drug and the type of cancer being treated. The side effects of chemotherapy are related to the effects of chemotherapy on normal – as well as cancerous – cells. The principal goal with cancer care in pets is to provide cancer control without reducing quality of life. With pets, chemotherapy protocols are purposefully designed so the treatment does not become worse than the disease.
Chondrosarcomas arise from cartilage, which is a connective tissue primarily found where bones meet with joints, as well as at other locations in the body (such as the nasal cavity, ribs, etc.). Chondrosarcoma is the second most common primary bone tumor in dogs. Canine chondrosarcoma most commonly affects the flat bones of the body, such as the ribs, skull, nasal cavity and pelvis, although the limbs can also be affected. Aggressive surgical resection is typically recommended, although radiation therapy may also be used (depending on location). Metastasis may occur, but is relatively uncommon.