Tonic-clonic convulsions in meadow voles.

Some meadow voles (Microtus pennsylvanicus) exhibit prolonged tonic-clonic convulsions, possibly epileptiform seizures, when handled or exposed to a strange environment. These convulsions are often preceded by a period of slow head shaking and/or stiff-legged hopping, but never by the explosively wild running bouts that characterize convulsions in some mammals. Convulsions occasionally occur in meadow voles in response to mild disturbance, as when an individual in its home cage is carried from one room to another. In contrast, they can not be elicited by some of the auditory or olfactory insults used to induce epileptiform seizures in other mammals. Breeding experiments have established the genetic basis of the convulsions seen in meadow voles, and of particular interest here is the fact that some of the convulsing voles were caught in the wild. This raises the interesting possibility that wild voles in natural habitats might be susceptible to convulsions when startled.