This influences their behavior in many ways. Cats are subject to gum disease and to dental caries. They should have their teeth cleaned by the vet or the cat dentist once a year. Cats, especially older cats, do get cancer. Many times this disease can be treated successfully.
Most cats have no eyelashes.
Many cats cannot properly digest cow's milk. Milk and milk products give them diarrhea. Cats lack a true collarbone. Because of this lack, cats can generally squeeze their bodies through any space they can get their heads through. You may have seen a cat testing the size of an opening by careful measurement with the head.