VITAMIN D
Did you know that dogs and cats, perhaps because their fur blocks their skin’s ability to absorb sunlight and produce Vitamin D, secrete an oil that converts to Vitamin D when exposed to sunlight? It then has to be ingested orally, which is one reason that pets are always licking themselves.
–Brooke Jarvis, reviewing Monty Lyman’s The Remarkable Life of the Skin
another eye opens 