Shampoo for animals (such as for
dogs or
cats) should be formulated especially for them, as their skin has fewer cell layers than human skin. Cats' skin is 2-3 cell layers thick, while dogs' skin is 3-5 layers. Human skin, by contrast, is 10-15 cell layers thick. This is the main reason why one should never use even something as mild as baby shampoo on a cat, dog, or other pet.
Shampoo intended for animals may contain
insecticides or other medications for treatment of skin conditions or
parasite infestations such as
fleas or
mange. These must never be used on humans. It is equally important to note that while some human shampoos may be harmful when used on animals, any haircare products that contain active ingredients/drugs (such as zinc in antidandruff shampoos) are potentially toxic when ingested by animals. Special care must be taken not to use those products on pets. Cats are at particular risk due to their instinctive method of grooming their fur with their tongues.