Proheart tablets are given once each month for the prevention of heartworm infections in dogs.Safety in dogsProheart tablets when used as directed, are safe to use in all dogs, including stud dogs and breeding bitches.  Do not use in puppies under 4 weeks of age. Contact your Veterinarian prior to administration of these tablets if your dog is not currently on heartworm prevention.  Active Ingredients: Moxidectin NOT TO BE USED FOR ANY PURPOSE, OR IN ANY MANNER, CONTRARY TO THE LABEL DIRECTIONS