"Chemodectoma" TUMOR TIDBITS, AN EMAIL NEWSLETTER FROM GULF COAST VETERINARY ONCOLOGY Number 107; October 10, 2003. ======================================================================= THIS WEEK'S ANNOUNCEMENTS FROM GULF COAST VETERINARY ONCOLOGY *Please call our Houston or San Antonio offices regarding our ongoing clinical trials. *Please visit our web pages about our Foundation Golf Tournament November 11th. ======================================================================= THIS WEEK'S TUMOR TIDBIT: Chemodectoma. ======================================================================= OVERVIEW Chemodectomas are any benign, chromaffin-negative tumor of the chemoreceptor system. The most common types are the carotid body tumor (arising along the mid-portion of the neck) and the aortic body tumor (arising near the heart-base region). They are uncommon in dogs and rare in cats. About 80-90% of chemodectomas in dogs are aortic body tumors, affecting dogs that are 10-15 years old. Boxers and Boston terriers most commonly affected. Males are predisposed to aortic body tumors, but no sex predilection for carotid body tumors exists. Chronic hypoxemia is a suspected risk factor. This may explain the predisposition of the brachycephalic breeds. CLINICAL PRESENTATION Aortic Body Tumor * Signs of congestive heart failure * Coughing * Dyspnea Carotid Body Tumor * Regurgitation * Dysphagia * Neck mass * Arteriovenous fistula in the neck Aortic and Carotid Body Tumors * Sudden death if acute hemorrhage from invaded blood vessels * Distant metastasis with associated signs of organ dysfunction in up to 20% of patients * Local invasion of blood vessels in up to 50% of patients Differential diagnoses * May include congestive heart failure, megaesophagus, or thyroid carcinoma. LABORATORY AND IMAGING FINDINGS * Review a complete blood count to identify anemia from bleeding; nucleated RBC may be present in some animals without anemia * Review a serum chemistry profile; high liver enzymes, BUN, and creatinine suggesting metastasis to liver or kidneys * Consider thoracic radiographs or cardiac ultrasonography to identify a heart-base mass, lung metastasis, or vertebral invasion in animals with an aortic body tumor TREATMENT APPROACH * Surgical removal is difficult because the tumors are highly invasive. Debulking carotid body tumors may be the treatment of choice, especially if the masses are somewhat freely movable. * Radiotherapy has been used successfully as adjuvant treatment to surgery in some dogs with carotid body tumor. * Pericardectomy or a pericardial window may be helpful in some dogs with pericardial effusion secondary to an aortic body tumor. * Chemotherapy may be considered to reduce tumor growth but reports to-date are anecdotal in response. PROGNOSIS * Median survival time in dogs following surgical removal (carotid body tumor) or pericardectomy (aortic body tumor) is 2 years (range 1 month to 5 years). ======================================================================= As always, we hope this info helps and don't hesitate to call or email us Gulf Coast Veterinary Oncology! Kevin A. Hahn, DVM, PhD, Diplomate ACVIM (Oncology), drhahn@gcvs.com Janet K. Carreras, VMD, Diplomate ACVIM (Oncology), drcarreras@gcvs.com Glen K. King, DVM, MS, Diplomate ACVR (Radiology & Radiation Therapy), drking@gcvs.com Gulf Coast Veterinary Diagnostic Imaging & Oncology 1111 West Loop South, Suite 150, Houston, TX 77027 P: 713.693.1166 F: 713.693.1167 W: www.gcvs.com ======================================================================= Copyright c 2003, Gulf Coast Veterinary Oncology