Heartworm prevention is critically important here in the Southeastern US. Heartworms are parasites transmitted by mosquitoes. They are very easy to prevent and can be fatal if infected. Often there are no clinical signs of heartworm disease until the pet is very sick. In agreement with the American Heartworm Society (https://www.heartwormsociety.org/) we strongly recommend annual testing and monthly prevention. There are many excellent, safe products available. Please feel free to discuss your options with us so we can pick the one that is right for your pet!