Each species of animal digests, absorbs, metabolises and excretes herbs differently. Because a herb is safe in humans, or one species of animal, doesn’t automatically mean it is safe in all species.

For example, cats are very sensitive to salicylic acid, found in willow bark, meadowsweet (the original source of aspirin). Because they metabolize it very slowly it can be poisonous at doses that are safe in other animals. Cats are also very sensitive to many essential oils. Tea tree oil, for instance, is potentially very toxic to cats and small dogs.