I once had a water spaniel, born in January, that ate his way through all the fruit - apples, pears, strawberries, raspberries, blackberries, gooseberries in the garden. Then he started on the vegetables - sprouts, cabbages, etc. etc. In October, when nothing in the garden was green, he collapsed!
He had a vitamin C deficiency. Vitamin C tablets from the chemist sorted him, and he lost his deficiency in his second year.
John