Behavioural changes in hamsters with otoconial malformations.

For a period of 10 months, the perceptive-motor skills of golden hamsters were tested as part of an experiment to investigate vestibular controlled behaviour. We found that four out of 40 hamsters had more difficulties with swimming and equilibrium maintenance than the rest of the group. These disturbances either were apparent during the first months of testing or developed at a later period. In three hamsters the disturbances persisted over time while in one hamster performance in perceptive-motor skills increased. Histological examination with scanning electron microscopy revealed otoconial abnormalities in the saccule and/or the utricle. The otoconia were either malformed or replaced by spherulites. We conclude that the observed behavioural disturbances were caused by a defective peripheral vestibular organ. The results show similarities with data from pathology in other animals as well as in the human inner ear.