A dog with a lesion in the left elbow area and presence of purulent materials was referred to hospital;history, clinical examination, laboratory test and radiological evaluation of the dog proved the presence of osteomyelitis. Eosinophilia was evident by haematologic test. Intensive antibiotic, anti-inflammatory medication, local wound management and restricted physical activity, improved osteomelitis condition and reduced eosinophil number. Therefore it seemed that osteomyelitis was the cause of eosinophilia in this dog.