Hiccups are a sign that something has caused the diaphragm, a large breathing muscle located just behind the lungs, to spasm. Occasional hiccups are normal in cats of all ages. Cat hiccups in older cats can be caused by many things, including gulping air from eating too fast, hairballs, intestinal parasites, heartworm disease, feline asthma, heart disease, cancer, food allergies, or ingestion of a foreign body.