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Dogs + Tumors

  • 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.

  • Esophageal tumors are extremely rare in dogs and cats. There are many kinds, including squamous cell carcinomas, leiomyosarcomas, fibrosarcomas, osteosarcomas, and undifferentiated sarcomas (all malignant); and leiomyomas and plasmacytomas (benign). Most tumors are malignant. These tumors occur mostly in the upper esophagus in cats and the lower esophagus in dogs. In dogs, most cases of esophageal sarcoma are associated with spirocercosis. Esophageal cancer causes progressive signs of regurgitation, difficulty swallowing, excessive salivation, weight loss, and lack of appetite. It is diagnosed with imaging, endoscopic or surgical biopsy, and histopathology. Surgery is a treatment option, with the possibility of radiation therapy for tumors of the upper esophagus. Avermectins may be used with benign spirocercosis. Palliative care may be possible with the placement of a feeding tube.

  • Infertility in a female dog is defined as the inability to conceive and deliver viable puppies, even when mated multiple times with a known fertile male surrounding the time of ovulation. This handout outlines the varying causes of infertility in female dogs and how they may be diagnosed and treated.

  • Intestinal tumors are uncommon in dogs and cats. There are many kinds, including leiomyosarcomas, lymphomas, adenocarcinomas, mast cell tumors, GISTs, plasmacytomas, carcinoids, and osteosarcomas (all malignant) and leiomyomas, adenomatous polyps, and adenomas (all benign). Most intestinal tumors are malignant. Intestinal tumors are more prevalent in older animals, males, and certain breeds. The signs of intestinal tumors vary according to the area of the intestinal tract that is affected, and can include vomiting, lack of appetite, lethargy and weight loss for the upper bowel and difficulty defecating, ribbon-like stools, and rectal prolapse with the lower bowel. Sometimes tumor ulceration causes anemia. Paraneoplastic syndromes are possible with the muscle tumors. Intestinal tumors may be diagnosed with imaging, endoscopy, or surgery, with a biopsy. Treatment may involve surgery, chemotherapy, or radiation therapy.

  • 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.

  • Radiation therapy is the medical use of high dose radiation to destroy cancer cells by damaging the cells’ DNA to interfere with cell replication and kill them. It may be used on its own or in combination with other treatments, such as surgery or chemotherapy, or to reduce the size of very large tumors prior to surgery. There are several radiation protocols used in veterinary medicine. Your veterinary oncologist will choose the therapy most appropriate for your pet’s individual situation.

  • Round cell tumors are among the most common skin tumors in dogs, and they typically form just under the skin, although they may change the surface of the skin above them. When caught early, most round cell tumors are removed easily, and surgery is generally curative. The most important take home message is to be vigilant, and to have any skin lumps or bumps assessed by your veterinarian promptly.

  • Seizures and syncope are commonly confused with one another due to similarities in the appearance of these episodes. Both present with collapse but there are several details, explained in this handout, that can differentiate between them, which is important for determining treatment. The prognosis for each condition varies depending on the underlying causes.

  • Skin gland, hair follicle, and sebaceous gland tumors are more commonly found to be benign. Matrical carcionoma and sebaceous gland adenocarcinoma are rare and more aggressive forms of the disease. Regardless of the type (sweat, hair, or sebaceous) diagnosis is made by fine needle aspiration, biopsy, and/or initial surgical removal and histopathology. In the majority of cases, surgery is recommended and other treatments are unnecessary. Chemotherapy and/or radiation therapy in pets with matrical carcinomas or sebaceous gland adenocarcinomas may be recommended.