Ovarian tumors are quite rare in North American pets, mainly due to routine spaying practices. Several types of tumors can arise from the tissues of the ovary. How the tumor will affect your pet is entirely dependent on the location and type of tumor. By far, ovarian cancer is most commonly diagnosed by abdominal ultrasound or during a spay procedure. Full staging is recommended prior to surgery to determine if the cancer has metastasized. Treatment for solitary masses without evidence of spread typically involves ovariohysterectomy. If metastasis is present, chemotherapy should be considered, however its efficacy is not completely known. Without evidence of spread, ovarian tumors carry a good prognosis.
Parathyroid tumors are uncommon in dogs and cats. Benign adenomas occur more often than malignant tumors. Keeshonds appear to have a genetic predisposition to developing parathyroid tumors, however no breed or genetic relationship has been established in cats. Pets may exhibit signs of lethargy, little or no appetite, vomiting, and muscle twitching. Diagnosis is confirmed with PTH testing and ultrasound of the neck region after hypercalcemia is observed on bloodwork. Surgery to remove the affect gland(s) is the typical treatment, however ultrasound-guided ablation may be pursued. Careful monitoring of calcium levels post-surgery is important, as some pets may develop a transient hypocalcemia and require calcium supplementation. Prognosis is excellent, and the metastatic rate for these tumors is extremely low.
Clinical signs of pituitary tumors depend on whether the tumor is functional or nonfunctional. Functional tumors can cause Cushing’s disease in dogs, and both acromegaly and insulin-resistant diabetes in cats. Nonfunctional pituitary tumors can enlarge to cause neurological signs. Diagnosis may be based on the history, bloodwork, urinalysis, and sometimes a CT scan or MRI. Medical therapy is often the treatment of choice for functional tumors. Radiation therapy is another option and is usually the primary treatment for nonfunctional tumors.
Plasma cell tumors develop as a result of dysregulated production of plasma cells and are relatively uncommon in dogs and cats. Some plasma cell tumors are benign and are typically confined to the skin or oral cavity, and most are very treatable. Surgical excision is the treatment of choice for removal of benign plasma cell tumors, with little to no recurrence if completely excised. Conversely, multiple myeloma is an aggressive cancer that is usually treated with chemotherapy.
Tumors of the prostate are relatively uncommon in dogs and extremely rare in cats. The most common tumor is prostatic adenocarcinoma. Clinical signs include blood in the urine, changes in urination habits, or straining to urinate or defecate. Metastasis to the pelvic bone and/or lumbar spine is likely. FNA of the prostate aids in the diagnosis, though surgical biopsy may need to be considered. Treatment is limited. Stents may be placed in patients with tumors obstructing the urethra. Radiation therapy in conjunction with NSAID therapy has shown significant survival advantage when compared to pets who did not receive NSAID therapy. The role and/or benefit of chemotherapy is not well understood.
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.