Pets are suffering from something more often associated with humans - an intolerance to certain foods.
Research has shown than one in 10 cats and dogs get ill when they gobble up stuff like wheat and dairy products.
It's thought that it might have come about because we feed our pets different food to what they ate in the old days.
Instead of eating scraps of human food, they're now more likely to have canned food or dried cereal biscuits.
Intolerance symptoms can include throwing up, dried skin or the pet being tired all the time.
Many pet owners are getting special diets drawn up by vets and some people are only feeding their animals home-made food.