Comparison of heartworm antigen test kit performance in dogs having low heartworm burdens

Sensitivity and specificity of four in-clinic heartworm antigen test kits, AbboScreen (Abbott Laboratories), Snap PF (IDEXX Laboratories), Solo Step ( HESKA Corporation), Witness (Synbiotics Corporation) and two heartworm anti gen microwell plate assays, DiroCHEK (Synbiotics) and PetChek PF (IDEXX) we re compared in a blinded study using serum or plasma drawn from 237 random source dogs, including 140 with necropsy-confirmed, low worm burden infecti ons (minimum 1 worm, maximum 10, mean 2.3, median 3) and 97 confirmed heart worm-free at necropsy. In general, microwell format tests were more sensiti ve than membrane format tests and tests using ELISA technology were more se nsitive than tests using lateral flow immunochromatographic technology. Per cent sensitivity and specificity, respectively, were PetChek PF 76 and 97, DiroCHEK 71 and 94, SNAP PF 67 and 98, Solo Step 60 and 98, and AbboScreen 52 and 96. The Witness test protocol was changed by the manufacturer midway through the study, and the newer version of this test kit arrived containi ng a package insert alerting the user to a change in procedure, which purpo rtedly resulted in improved sensitivity. PetChek was significantly more sen sitive than all other tests except DiroCHEK and the new version of Witness. DiroCHEK was significantly more sensitive than all tests except PetCheck, SNAP and the new version of Witness. Snap was more sensitive than AbboScree n and the old version of Witness. Differences in specificity were not signi ficant (P > 0.05). (C) 2001 Elsevier Science B.V. All rights reserved.