The occurrence of tarsal injuries in male mice of C57BL/6N substrains in multiple international mouse facilities

Abstract

33Dislocation in hindlimb tarsals are being observed at a low, but persistent frequency in adult 34 male mice from C57BL/6N substrains. Clinical signs included a sudden onset of mild to severe 35 unilateral or bilateral tarsal abduction, swelling, abnormal hindlimb morphology and lameness. 36Contraction of digits and gait abnormalities were noted in multiple cases. Radiographical and 37 histological examination revealed caudal dislocation of the calcaneus and partial dislocation 38 of the calcaneoquartal (calcaneous-tarsal bone IV) joint. The detection, frequency, and cause 39 of this pathology in five large mouse production and phenotyping centres (MRC Harwell, UK; 40