Raw eggs. These could give your cat food poisoning from bacteria like salmonella or E. coli. But that's not the only concern. Avidin, a protein in raw egg whites, interferes with the absorption of the B vitamin biotin. That can cause skin problems like dermatitis, as well as hair loss.
Milk. Many cats are lactose-intolerant, which means they cannot break down the milk sugar in diary products. If yours laps up some milk and then shows signs of diarrhea or dehydration, it may be smart to eliminate such products. Lactose-free brands of milk designed for cats are available at pet stores.
If you suspect your pet has wolfed down something he shouldn't have, don't wait around to see if he improves. "Call your family vet right away, or the local emergency vet if it's after hours," Ryan says. And the American Society for the Prevention of Cruelty to Animals' Poison Control Center has trained veterinary toxicologists on-duty around the clock. A phone consultation costs around $65.