Cynthia Foley provides a thorough discussion of the hypoallergenic description, its history, lack of regulatory basis and suggests it is the best word we have for less-likely-to-cause-allergic-reactions. She opines the products that are marketed as particularly gentle or for dogs with particularly sensitive skin should be held to a higher standard than regular shampoos.
Source: Whole Dog Journal, June 2017.
Dog shampoos that claim to cure, treat, or otherwise mitigate a disease or ailment are regulated by the FDA’s Center for Veterinary Medicine. Dog shampoos that claim to kill or control fleas or ticks fall under the regulatory purview of the Environmental Protection Agency. But “regular” dog shampoos, “hypoallergenic” or otherwise, fall under the category of “grooming aids,” which are not regulated by any governmental or non-governmental agency in this country.