Results of recent trials show that Vitamin C influences bone development and strength through its effects on the production of vitamin D metabolites and calcium-binding protein.
Vitamin D3 supplied in a feed supplement is transported to the kidneys for conversion to the active metabolite form. Latest studies show that vitamin C is required to achieve optimum conversion of vitamin D3 into these active metabolites. Improvements in bone synthesis appear to be directly related to an increase in the conversion of vitamin D3 to the active metabolite and to the increase of calcium-binding protein through the influ-
ence of supplemented vitamin C in the diet.
At times of stress unfortunately absorption of vitamin C from the gut may not be fully ef- fective, therefore daily supplementation is recommended.
In large breeds of dogs, hip dysplasia, long considered to be an inherited birth defect, may be an easily controlled biochemical condition. The lesion in hip dysplasia appears to merely poor quality, low strength collagen in the affected ligaments. In litters from dysplastic German Shepherd parents or parents that produced dysplastic offspring, there have been no signs of hip dysplasia when the bitches were given higher than nor- mal doses of vitamin C during pregnancy and the pups were given daily doses of vitamin
C until they reached young adulthood.
In potentially dysplastic pups of large breeds, the first year or two of life is a high stress period. The demands on the body are great, the demands for large quantities of vitamin C even greater. The laxity of the hip ligament and changes in the pectineus muscle and tendon, consequent upon lack of high quality collagen is evident. The weak collagen in the ligaments causes them to stretch or loosen, resulting in joint laxity, which allows the
young femoral head to separate from the hip socket.
After separation of the femoral head from the acetabulum, an inflammatory process (arthritis) ensues. Varying amounts of scar tissue form in the acetabulum, preventing the head of the femur from returning to its normal position. This results in coxofemoral subluxation (hip dysplasia). Simultaneously, the poor quality of collagen in the pec- tineous muscles and ligaments retards their growth and development. The impaired growth and development of tendon and muscle, together with the rapid growth of the
femur, contributes further to the cause of the dislocation.
In trials conducted over a five-year period using eight litters of German Shepherd pup- pies from dysplastic parents, or parents known to have produced dysplastic offspring, none of these pups which have been maintained on high doses of vitamin C have, to date, shown dysplasia. The regime consists of giving the pregnant bitch high doses of
vitamin C in the ration daily. At birth, the pups are given 50 to 200mg of vitamin C orally.
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