The drug -- produced by Ford Dodge Animal Health of Overland Park, Kan., a part of the Wyeth Pharmaceutical Co. -- had been withdrawn because of serious, life-threatening reactions, including loss of appetite, lethargy; vomiting and seizures, followed in some cases by death.

The FDA said it is allowing the reformulated ProHeart 6 (moxidectin) Sustained Release Injectable for Dogs to be sold under a risk minimization and restricted distribution program designed to provide for safe, appropriate use of the product, while minimizing risk to dogs.

"This is the first veterinary drug to be marketed under a risk minimization and restricted distribution program," said Dr. Bernadette Dunham, director of the FDA's Center for Veterinary Medicine. "Numerous drugs for use in people have been successfully marketed under similar programs."

The FDA said the risk minimization and restricted distribution program requires veterinarians who wish to purchase ProHeart 6 to register with the company and participate in an Internet training program prior to obtaining the product.