Heartgard Plus for Dogs is a standard medicine used to treat dogs with diseases like Canine Distemper, Lassa, and Heartworms. This medication is given to dogs every six weeks to ensure that their immune systems are as strong as they can be. As with other medicines, Heartgard Plus for dogs' ingredients can sometimes cause adverse reactions in your dog, especially if you've never taken this type of treatment before. While Heartgard Plus for dogs is generally safe to give, it's still important to talk to your vet about what kinds of foods and treats you can give your dog.