Vet clinic to offer free heartworm tests May 21 Published May 14, 2013 28th Bomb Wing Public Affairs ELLSWORTH AIR FORCE BASE, S.D. -- The first 50 dog owners eligible to receive care at the Ellsworth Veterinary Treatment Facility will receive free heartworm tests for their four-legged friends during a special event, May 21. Heartworm tests, which normally cost $25, will be administered during Heartworm Day from 8 to 11 a.m., and from 1 to 3 p.m., at the facility located in Bldg. 6010. No appointment is necessary. Over-the-counter sales will be the only other services provided that day. For more information, call the VTF's appointment line at (605) 385-1589.