Brain and ocular metastases from a transmissible venereal tumour in a dog

A five-year-old crossbred dog was referred with rapidly growing masses over its penis and right popliteal lymph node. The dog had severe blepharospasm , congestion of episcleral vessels and rubeosis iridis of the left eye. A p resumptive diagnosis of transmissible venereal tumour (TVT) and iridocyclit is was made based on the results of fine needle aspiration. Chemotherapy wi th vincristine and prednisolone was initiated and after four months the dog made a complete recovery. However, the dog subsequently relapsed, showing miosis, blepharospasm and a well defined mass within the anterior chamber o f the left eye. In addition, the dog exhibited generalised 'grand mal' type seizures. Computed tomographic (CT) examination of the brain revealed two distinct masses in the left frontal lobe, Because of the poor prognosis, th e owners elected to have the dog euthanased, On histopathology, metastases of TVT in the left eye and left cerebral hemisphere were found, showing no specific staining for CD3, immunoglobulin (Ig) G, IgM and lambda light chai ns. It was therefore concluded that the tumour growth was progressive, and that there was an absence of local humoral immune response against TVT in t his case.