Management and Outcome of Intracardiac Heartworms in Dogs

Abstract

Abstract Background Intracardiac heartworm (IH) disease is a serious condition that can become life threatening if the patient develops caval syndrome. We aim to describe the management and outcome of IH in dogs evaluated by Medvet’s New Orleans cardiology service from November 2015 to December 2021. Methods Records of 27 dogs with IH were examined retrospectively. Follow-up information was obtained from phone conversations with referring veterinarians and owners. Results 9/27 dogs had a previous diagnosis of heartworm disease and were undergoing “slow kill” treatment, 12/27 dogs heartworm disease was a new diagnosis, and 6/27 had either scheduled or started adulticide therapy. Nine dogs had heartworm extraction. No dogs died during the heartworm extraction procedure. 4/9 dogs have died (survival time 1; 676; 1,815 and 2,184 days). One dog died the day after the procedure secondary to continued respiratory distress, the other 3 died of non-cardiac causes. 5/9 are alive (median follow up 1062 and range of 648 to 1831 days). Eleven dogs had IH resolution. In 7/11 this occurred while undergoing stabilization for heartworm extraction. In 4/11 heartworm extraction was not recommended due to low IH burden. All dogs with IH resolution were discharged from the hospital. 4/11 have died (survival time 6; 22, 58 and 835 days) and 6/11 are alive (median follow up 523 and range of 268 to 2,081 days). One was lost to follow up after 18 days. Five dogs were medically managed. In 1/5 dogs, extraction was not recommended due low IH burden. In 4/5 extraction was recommended but declined. 1/5 has died (survival of 26 days) and 4/5 are alive (follow up of 155; 371; 935 and 947 days). Two dogs were euthanized at the time of diagnosis. 15/27 dogs were considered to have caval syndrome. Conclusion The results suggest that patients with IH resolution have a good long-term prognosis. Most often IH resolution occurred while undergoing stabilization for heartworm extraction. When IH are present, heartworm extraction should still be considered the treatment of choice and recommended as 1st line therapy whenever possible.