Vitamin A

Vitamin A is a fat-soluble vitamin essential for vision, the integrity of skin and mucous membranes, bone growth and immune defence. Here the dog and cat diverge sharply: dogs can convert plant carotenoids such as beta-carotene into active vitamin A, but cats cannot, and so must receive preformed vitamin A from animal tissue such as liver or fish oil, a defining hallmark of the cat's obligate-carnivore status. Vitamin A is needed within tight limits, because excess is toxic, especially in cats. The figures are striking: in pregnant queens, feeding 100,000 IU per 100 g of dry matter caused severe fetal malformations in studies, whereas 2,000 IU per 100 g caused no adverse effects, and FEDIAF sets a nutritional maximum near 33,330 IU per 100 g of dry matter for breeding females (FEDIAF, 2021). Deficiency causes eye disorders, a poor coat and weakened immunity. Chronic over-supply produces a particularly painful condition in cats, hypervitaminosis A, in which excess vitamin A drives bony growths along the spine and joints, classically linked to liver-heavy home diets. In a complete commercial food, levels are formulated to stay safely inside the window. On a label vitamin A appears among the added vitamins, often in international units. See the [Petipedia glossary](/glossary).

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