When pets are young, it is important that the gut barrier be strengthened. Young animals are born with leaky or open guts. This allows absorption of immune system proteins from their mothers’ first milk that will protect them from disease. Young pets always need deworming, and sometimes prescriptions, to kill off parasites. The gut remains slightly open to protein absorption throughout life, and so veterinarians use an animal’s excrement to judge and manage reactivities to different foods. Healthy excrement is firm excrement usually, unless an animal is dehydrated.