These notes are provided to help you understand the diagnosis or possible diagnosis of cancer in your pet. For general information on cancer in pets ask for our handout "What is Cancer". Your veterinarian may suggest certain tests to help confirm or eliminate the diagnosis, and to help assess treatment options and likely outcomes.
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.
Cats have a pair of anal sacs, one located on each side of the anus between the external and internal anal sphincter muscles. The sacs are lined with modified sweat glands called anal glands.
The bone marrow is the soft tissue inside the bones. Before birth, the marrow contains the primary (stem) cells that from all the red and white blood cells. After birth, some types of blood cells, particularly lymphocytes, are made in other parts of the body.
As continuous improvements in our knowledge and new and evolving methods of treatment are developed, pet owners and their veterinarians have more options available when cancer is diagnosed.
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 a rare tumor in cats, but it can occur. The reason why a particular pet may develop this, or any tumor or cancer, is not straightforward. Clinical signs of chondrosarcoma may vary significantly, depending upon where the tumor arises. Although the mass may grow rapidly, less than 20% of feline chondrosarcoma cases metastasize to other parts of the body. Therefore, surgical removal is curative in many cases.
All tissues and organs of the body may develop cancer (an abnormal overgrowth of their constituent cells). Every organ (liver, lungs, spleen, kidneys and so on) contains a supporting framework of fibrous connective tissue as well as nerves to relay information to and from the brain.
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.