I highly doubt it as humans and dogs and many other mammals synthesise their own vitamin C - so if the dog is getting the correct food then you do not need to supliment. The odd carrot as a treat though wouldn't hurt :-)
Humans do NOT synthesise their own vitamin C; if they did scurvy would not exist!
Dogs do synthesise their own vitamin c however just as in everything else it does not mean they synthesise enough for their particular needs.
I give mine Vitamin C and if I wanted to find a vegetable or fruit to provide Vitamin C I doubt I would choose a carrot; as of course they are high in Carotene, a form of Vitamin A!
hi there ive read in the past that giving extra vit c has helped dogs down on their pasterns.never needed to try it but some breeds do swear by it ,apparently they will pee out what they dont need.hope this helps,roy.