Paraneoplastic pruritus in a 7-year-old Slovak Warmblood with malignant round cell tumour

A 7-year-old Slovak Warmblood gelding, used as a police horse, initially presented to the referral clinic as a 5-year-old, with a prominent nonhealing, itchy hypertrophic scar on the distal limb, which required surgical removal. After removal of the scar and successful closure of the skin, it was necessary to bandage the healing wound to prevent self-mutilation as the site remained pruritic post-operatively. Two years later, the horse was presented to the clinic again, but this time with pruritic and alopecic regions of the head, neck, limbs and base of the tail. Attempts to find the cause of dermal irritation included dermatological, parasitological, microbiological and ultrasonographic examination. Treatment with corticosteroids, antiparasitics and antibiotics were not successful. Further investigation, due to the horse's worsening general status, subsequently identified marked pleural effusion. Cytology of the pleural fluid confirmed there was, as suspected, neoplastic changes in the thoracic cavity. Upon post-mortem, there were gross pathological changes of the lymphatic tissue of the cranial mediastinum, surroundings of the thoracic aorta and the lymph nodes of the abdominal cavity. Histology of the lymphatic nodes confirmed poorly differentiated round cell tumours. Histopathological findings suggested that there was a very aggressive form of lymphoma present. The pruritus, generalised moth-eaten alopecia and self-mutilation were the first symptoms of terminal disease in this case.