For those giving their furry friends "grain-free" dog food, you might want to think twice.

Unusual cases of a potentially deadly heart disease have been occurring in dogs that have been eating "grain-free" dog food containing legumes and potatoes, spurring the FDA into conducting an investigation.

DVM with Highview Animal Clinic, Doctor Krista Gavel, says, "what makes this case even more unusual is that it's occurring in all dog breeds, even those that are not predisposed to heart disease."

Over 200 cases have been reported so far, and the FDA is recommending those feeding their dogs this diet to consult with a licensed veterinary professional about changing their diet.

Doctor Gavel says, "people often feed their dogs a "grain-free" diet out of the assumption that it's more healthy but there is absolutely no research in dogs to indicate that it's true. Feeding grain-free diets in 99% of the cases is purely a fad or a boutique type of experience. There's no benefits to the dogs."

Affected dogs may seem tired, weak, lose weight and/or even collapse suddenly.

If you're concerned, contact your vet immediately.