Why do dogs not having grey hairs ?

One of the reasons I found out is that animals like dogs can produce Vitamin C in their liver.
The amount can go as high as 10g per day produced depending on their stress level and various conditions.
Polar bears although so padded with fat but never got a heart attack. Anyway has anyone seen a dog died of
heart attack ?

Unfortunately for humans and some species of apes and guinea pig somehow lost the ability to produce
vitamin c in their body but has to take in from outside ! a genetic defect indeed !

To most humans 1000mg of ascorbic acid should be ok ! Nothing to be afraid of !