Innes (1931) demonstrated that the dog was independent of a dietary supply of vitamin C. Puppies fed a diet devoid of vitamin C for 147 to 154 days showed neither growth impairment nor lesions of bones and teeth, although the same diet killed guinea pigs within 25 days with severe signs of scurvy. Furthermore, the livers of dogs on the deficient diet contained the vitamin in sufficient amounts to prevent the onset of scurvy in guinea pigs, indicating that the dog can synthesize vitamin C. Naismith (1958) showed that this synthetic ability is present in puppies during the first weeks of postnatal life.
Naismith and Pellet (1960) reported that the concentration of vitamin C in the milk from bitches is approximately four times that of the blood. The comparative rates of liver synthesis of vitamin C in dogs and cats appear to be lower than those in ruminants, rodents, and rabbits (Chatterjee et al., 1975). Dogs synthesized vitamin C in the liver at a rate of 5 µg per mg of protein per hour while cows, rats and rabbits had rates of 68, 39, and 23 µg per mg of protein per hour, respectively.
