Handling-induced tonic/clonic seizures in captive born bank voles (Clethrionomys glareolus)

Handling-induced seizures observed among 23 of 333 captive born bank voles was characterized by tonic/clonic convulsions, occasionally accompanied by an apparent loss of consciousness. Seizures were never observed among wild caught voles (N = 71). Median age for first observation of seizures was 157 days. Median latency to onset following mild handling was 12.6 s and median time to resumption of normal behaviour after arrest of convulsions was 28.05 s. Consecutive daily tests to provoke seizures indicated that more seizures were elicitated on the first day of testing (25.6%) compared to the following 4 test-days (8.7%). Incidence of seizure prone (SP) voles declined from 10.2% in F1 to 5.1% in F2 with no sex bias. A possible explanation for this decline could be that all F1 voles (N = 118) descended from non-stereotyping (N-Ster) parents where the majority of F2 voles (n = 138) descended from two stereotyping (Ster) parents: incidence of SP voles were five times higher among offspring from N-Ster parents than Ster parents (10–11% vs. 2.2%; p < 0.0001). However, the development of stereotypic behaviours did not affect seizure proneness. Roughly one-third of the captive born voles developed diabetes. However, the disease did not affect seizure proneness. SP voles were distributed among the litters (n = 60) in accordance with the negative binomial distribution, which indicate a “lumped” distribution. The proportion of SP voles which had SP full siblings, was significantly higher than the proportion of non-SP voles having SP full siblings (15/23 vs. 30/310, p = 0.0001), which, taken together, suggest the possibility for future establishment of lines differing in seizure proneness.