Some observations on the dietary vitamin D requirement of weanling pups

A study was conducted to test the hypothesis that growing dogs do not require supplementation with cholecalciferol (vitamin D-3) in a nonpurified extruded diet. Twenty-eight weanling pups from four litters of English pointers and two litters of German Shepherd dogs were allotted equally to two groups by gender and weight. Dogs were raised in indoor-outdoor kennel runs for the 102-wk evaluation. One group was fed a diet that contained no added vitamin D while the other group was fed the same diet to which had been added 60.5 micrograms cholecalciferol/kg diet. Both diets contained approximately 14% calcium and 1.0% phosphorus. Growth as measured by body weight and length, serum calcium, phosphorus and alkaline phosphatase and urine hydroxyproline were not significantly different (P greater than 0.05) between the two treatment groups. There was no relationship between dietary treatment and nutritional secondary hyperparathyroidism (NSH), rickets or other skeletal abnormalities. The data support the concept that addition of vitamin D to typical commercial dog foods for purposes of prevention or amelioration of rickets, NSH or other skeletal diseases is unnecessary.