Overview

• Chemodectomas are tumors arising from the chemoreceptor cells (such as in the aortic body and the carotid body).
• Other names-aortic body tumors, cardiac paraganglioma, APUDoma (amine precursor uptake decarboxylase), and glomus body tumor.
• Aortic body tumors more common (80–90%) in dogs than carotid body tumors (10–20%).

Signalment

• Rare in cats.
• Dogs age 6–15 years.
• Any breeds-but brachycephalic breeds predisposed-especially boxers, Boston terriers, English bulldogs, and German shepherd dogs.
• Males predisposed for aortic body tumors, no sex predilection for carotid body tumors.

Signs

• Nonspecific and dependent upon tumor size and anatomic localization, and can include lethargy, anorexia, weakness, collapse, coughing, respiratory distress, exercise intolerance, distended abdomen, vomiting, sudden death.
• Carotid body tumor-may notice neck mass, regurgitation, dyspnea, Horner's syndrome, laryngeal paralysis.
• May be associated with pericardial effusion and cardiac tamponade-muffled heart sounds, poor pulses, tachycardia, tachypnea, weak pulses, slow capillary refill time, ascites.
• May be associated with cranial vena cava syndrome (edema of head, neck and forelimbs), and in long-standing cases peritoneal effusion might develop consequent to right-sided heart deficits.
• May be associated with pleural effusion-decreased lung sounds ventrally, cyanosis.
• Cardiac arrhythmias with pulse deficits.

Causes & Risk Factors

Chronic hypoxia may play a role in the development of this disease in brachycephalic breeds.

Differential Diagnosis

• Other masses located at the heart base (i.e., hemangiosarcoma, thymoma, ectopic thyroid carcinoma, mesothelioma, abscess, and granuloma).
• Idiopathic pericardial effusion.
• Pericarditis.
• Cardiomyopathy.
• Valvular insufficiency.

CBC/Biochemistry/Urinalysis

Typically normal, but 36% of patients can have nucleated red blood cells without anemia.

Other Laboratory Tests

N/A

Imaging

• Thoracic radiography-to evaluate for mass in the region of the heart base, pericardial effusion, metastatic lesions in the lungs.
• Cervical ultrasound, CT or MRI-to evaluate for masses arising in the neck.
• Echocardiography-to image mass and aorta/pulmonary arteries/veins.

Diagnostic Procedures

• Biopsy of mass.
• ECG-if evidence of arrhythmia, may see low-amplitude QRS complexes with pericardial or pleural effusion, or electrical alternans with pericardial effusion.

Aortic Body Tumors

• Surgical removal of mass-if possible.
• Subphrenic pericardectomy has been shown to prolong survival.
• Symptomatic pericardiocentesis or thoracocentesis.
• Conformal radiation therapy.
• Palliative thoracoscopic-guided pericardial window.

Carotid Body Tumors

Surgical removal if possible-discuss with owners possibility of postoperative Horner's syndrome and laryngeal paralysis.

Both

Possible role of chemotherapy (doxorubicin) and radiation therapy; however, definitive studies are lacking.

Drug(s)

• The role of chemotherapy in this disease has not been published.
• Pharmacologic intervention for cardiac insufficiency.

Patient Monitoring

Serial thoracic radiography or advanced imaging for monitoring tumor progression and metastasis.

Expected Course and Prognosis

• Carotid body tumors treated with surgery-median survival time 25.5 months.
• Aortic body tumors-animals treated with pericardectomy MST 730 days versus animals that did not have pericardectomy MST 42 days. Larger tumors (as determined by tumor weight to body weight ratio) more likely associated with metastasis.
• Conformal radiation therapy in 1 dog – survival >42 months.

Pregnancy/Fertility/Breeding

It is not recommended to breed animals with cancer. Chemotherapy is teratogenic-do not give to pregnant animals.

See Also

Pericardial Effusion

Abbreviations

• ECG = electrocardiogram
• MST = median survival time