Vitamin E has a wide margin of safety in animals, and little information is available for toxicity considerations for dogs and cats. Compared with vitamin A and vitamin D, both acute and chronic studies with animals have shown that vitamin E is relatively nontoxic but not entirely devoid of undesirable effects. However, prolonged excessive consumption of tocopherol may have a depressing effect on the absorption of the other fat-soluble vitamins, and extraordinary parenteral doses (100 to 200 mg per kg per day; 45.5 to 90.0 mg per lb) in kittens have induced hepatosplenomegaly and death (Ralston Purina, 1987). It has been observed that although vitamin E did not interfere with coagulation in normal dogs, it was able to block oxidation of vitamin K to the epoxide form in warfarin-treated dogs and thereby exacerbated the coagulopathy (Corrigan, 1979). Hypervitaminosis E studies in rats, chicks and humans indicate maximum tolerable levels in the range of 1,000 to 2,000 IU per kg (455 to 910 IU per lb) of diet (NRC, 1987).
