A heartworm medication may not be safe for dogs.

Fort Dodge Animal Health has agreed to immediately cease production and recall its heartworm medication ProHeart6 from the market.

The U.S. Food and Drug Administration requested the product be recalled while further research is conducted into reports from pet owners and veterinarians that dogs were having adverse reactions to the product.

The FDA has observed an increase in the number of cases associated with liver and bleeding abnormalities in dogs followed in some cases by death.

The FDA asked Fort Dodge Animal Health to develop a strategy to help prevent such problems in the future before the product is marketed again. The FDA will convene an independent scientific advisory committee to thoroughly evaluate all available data.

The FDA is also advising veterinarians to avoid using the product on dogs until further notice.

ProHeart6 is an approved, injectable heartworm prevention product for dogs.

Heartworm disease is a serious and potentially fatal condition of dogs, cats, and other species of mammals. The parasite that causes heartworm disease is transmitted through the bite of a mosquito.

As of Aug. 4, the FDA's Center for Veterinary Medicine had received 5,552 adverse event reports for ProHeart6.