FORT WORTH, Texas - If your dog has heartworms it will be harder to get a cure. The only company producing the parasite-killing drug has run out and veterinarians don’t know when they’ll get more. Veterinarians across the country are in a quandary because Immiticide is the only FDA-approved drug available to treat dogs with heartworms. Drug company Merial said its supply is gone and it can’t produce any more because it can’t get the drug’s active ingredient in the United States. The FDA has been hesitant to allow overseas suppliers to fill American orders. Vets are working with what...