Day 21: At the originally scheduled weaning day (day 21), the home cage was placed into the testing room for at least 10 minutes. After this the pups were weighed and placed individually into an empty opaque cage (observation cage; similar to the housing cage as described above) for close inspection. There each animal was screened for apparent deviations from fluid gait, horizontally extended tail position, normal body position (e.g. hunched back), normal body proportion (e.g. lumps) and normal respiration while moving freely in the cage. While being restrained in a dorsal position, signs of dehydration (lifting a skin flap between index finger and thumb), general fur condition (smoothness), the presence of wounds, trimmed whiskers, presence of discharge in nose and the anogenital region, general eye condition and skin colour were recorded. Muscle tonus in fore/hind legs and abdomen was recorded by applying slight pressure with the index finger of the free hand.