Abstract
The sensitivity and specificity of a commercial heartworm (Dirofilaria immitis) antigen test kit were evaluated in 100 dogs with and without heartworm infections. All 25 microfilaremic heartworm-infected dogs, in which the number of heartworms ranged from 3 to 91, were identified correctly as positive (sensitivity: 100%). The test detected occult infection in 18 of 25 (72.0%) dogs. All heartworm-free dogs with (25 dogs) and without (25 dogs) roundworm (Toxocala canis) infection were indentified as negative (specificity: 100%). The accuracy in all 100 dogs tested was 93%. Changes in the circulating antigen levels after surgical heartworm removal were examined in 10 dogs using this kit. By surgical treatment, all heartworms were removed in 6 dogs, and removal efficiency ranged from 65.5 to 86.7% in the 4 other dogs. After heartworm removal, the circulating antigen levels declined in all dogs. The mean antigen level in 10 dogs was×730±1238 before removal, ×84±98 at 4 weeks after removal, ×36±39 at 8weeks after, and ×14±8 at 12 weeks after. There were no dogs in which the circulating antigen disappeared.
