Idiopathic phenobarbital-responsive hypersialosis in the dog: an unusual form of limbic epilepsy?

Three unusual cases of salivary gland enlargement and hypersialosis in the dog that responded to anticonvulsant therapy are reported. Presenting complaints included weight loss, hypersalivation, retching and vomiting of several weeks' duration. Two dogs were presented with enlarged painful mandibular salivary glands. The third dog exhibited bizarre behaviour (including jaw chattering) and developed enlarged painful mandibular salivary glands during hospitalisation. Fine needle aspirate cytology and biopsies from the enlarged salivary glands revealed no significant pathological changes. In one dog, an electroencephalogram revealed changes consistent with epilepsy. Hypersialism and salivary gland enlargement resolved completely during phenobarbital administration in all cases. Two dogs were successfully weaned off treatment six months after diagnosis. The remaining dog relapsed after eight months, but normalised with the addition of oral potassium bromide. It is hypothesised that the syndrome idiopathic hypersialosis may in fact be an unusual form of limbic epilepsy.