"The most common is kidney disease, then pancreatitis and then food allergies," Halligan said. Even flea sensitivity can cause a cat to vomit - and go bald.
Some owners swear by grain-free food as a way to reduce tummy troubles, or by adding bran or fiber, pumpkin, prunes, psyllium hulls or slippery elm to the cat's diet. But Halligan advises consulting with a vet before making dietary changes.
She's added pumpkin to cat food to remedy constipation, but she noted that cats are carnivores, programmed to eat animal protein, and may have trouble processing carbohydrates.
On the other hand, she said, a diet of nothing but grain-free food is not necessarily good either. "Grain-free is low in carbohydrates and high in protein," she explained. "Some of the cheaper foods use corn or other vegetables as the protein source, which is not good for cats. The grain-frees have done well because they have lower carbohydrates and essentially are a high-protein diet. But we are not sure how that's going to affect the kidneys long-term because it's a lot of protein. It might be too much. You can feed some grain-free but that shouldn't be their main diet."
Halligan's cats eat only canned food. She recommends pet owners feed their pets at least 50 percent canned food - and believes 75 percent would be better. "The only benefit of dry is that it's cheaper," she said, adding: "My cat Nathan, if I give him regular dry cat food, he vomits like crazy. Once I switched over to canned, no vomiting."
Excessive vomiting may require blood tests or X-rays to reveal the problem. Cats will eat catnip mice, needles and thread, buttons, earrings, erasers, tin foil balls, and almost any other small thing they can bat around, Halligan said.
"They will play with it, then swallow it. My cat has a fetish for rubber bands. Those things keep vets in business."
Hairballs can also get stuck in a cat's intestines. A cat that stops eating for 24 or 48 hours and repeatedly vomits is at risk for dehydration and liver failure. In as little as three days, jaundice can set in, with telltale symptoms of yellowing of the gums, ears and whites of the eyes. Fast treatment by a vet is essential.
"If you get them to us on time, we can probably save them," she said.