ABSTRACT
The idiopathic hypereosinophilic syndrome is a part of the yet rather unknown diseases and the aetiology remains at the least hypothetical. This syndrome is characterized by a variable hypereosinophilemia as well as a massive infiltration of several organs by mature eosinophils, causing an important tissue damage leading to organ dysfunctions and resulting in the patient death. In this reported case, the acute idiopathic hypereosinophilic syndrome was diagnosed in a 4-year rottweiler female dog based on an increased eosinophilemia and the infiltration of stomach, small intestine, colon, pancreas, spleen, ganglions, skin, lungs and bone marrow by mature eosinophiles. The acute development of the disease precluded any therapeutical hope success.