Cats are experts at hiding their clinical signs. Evolutionarily, cats are programmed to conceal signs of illness. Predators instinctively look for the weakest or sickest animal to prey on, so cats do everything they can to pretend that they’re not sick until they simply can’t hide it anymore. By the time the cat reveals to the owner that he is sick, the illness may have progressed too far to successfully treat. Early detection of illness is the key to keeping your cat healthy.