Myotonia congenita is a skeletal muscle channelopathy reported to occur naturally in humans as well as mice, water buffalo, sheep, goats, dogs, cats, horses, pigs and cattle, for which associated variants in CLCN1 have been reported in each species except cattle which remains undetermined [4,10,11,12,13,14,15,16,29]. Here, CLCN1 is linked to Thomsen and Becker disease.