It is the policy of our veterinary clinic that all patients will receive a heartworm check before we will dispense heartworm preventative. It is under the recommendation of the American Heartworm Society, as well as the American Veterinary Medical Association, that we have made this our policy. Our clinic also recommends that heartworm preventative be given to your pet year round. The American Heartworm Society has developed a very informative website that details the reasons and health benefits for using year round preventative. Their website can be found at http://www.heartwormsociety.org/think12/. For further information, you may feel free to contact us at (712) 323-2147.