LAUSR

Cardiac tumors are relatively rare in dogs and cats. They account for only a minor percentage of all neoplasms found in dogs. The most common cardiac tumors are hemangiosarcoma (HSA), heart base tumors (chemodectoma) and lymphoma. The incidence of a heart base tumor among all heart tumors in small animals is estimated at 27.9% (4, 15). In addition, the following cardiac tumors are also being reported: myxomas, rhabdomyosarcomas and chondrosarcomas (11). Clinical symptoms mainly depend on the tumor location and size. These neoplasms can cause no clinical symptoms or clinical signs can vary from mild up to severe, lifethreatening ones. Clinical symptoms may depend on the histological type, but they mainly result from the tumor’s influence on the hemodynamics of blood flow or are due to fluid or blood accumulation in the pericardial sac (15). In everyday veterinary practice, the most useful diagnostic tool is transthoracic echocardiography, but also more advanced diagnostic tools such as computed tomography (CT), positron tomography (PET) scans and magnetic resonance imaging (MRI) are used (9). Treatment options include surgery, chemotherapy and radiotherapy. Heart base tumors are neoplasms that occur in the proximity of major blood vessels. Their growth is assessed as slow and sometimes for many months or years they do not give any clinical symptoms and can be found accidentally. Larger tumors put pressure on the heart tissue including the aorta or pulmonary artery, making it difficult for blood to flow from the left or right ventricle. Heart base tumors are most common in brachycephalic breeds such as Boxers, English and French Bulldogs, and Boston Terriers. It is assumed that due to the specific structure of the skull, chronic hypoxia causes irritation and overgrowth of chemoreceptors (5, 11, 12). Heart base tumors include non-chromophilic paragangliomas (aortic carcinoma, nonchromaffin paraganglioma) and adenomas or adenocarcinomas originating from ectopic thyroid tissue (5-10%) (12). The chemodectoma is a tumor derived from chemoreceptor cells originating Chemodectoma located in the left atrium in 11 month survival dog with the use of palliative therapy