Fig. 1
Serum samples were collected from all study dogs monthly throughout this study. Heartworm antigen concentration was tested using the DiroCHEK® for both pre- and post-heat-treatment of samples. The optical density for both samples was read at 490 nm. No significant differences were found between these two methods with respect to the distribution of categorical labeled negative, slightly positive and positive antigen results according to visual color change. However, analyses of the actual optical density values resulted in absorption values post-heat-treatment as being significantly higher (P < 0.05) than those results pre-heat-treatment on study days 28 (t(29) = 3.98, P = 0.0004), 84 (t(30) = 5.40, P = <0.0001), 112 (t(30) = 4.89, P = <0.0001), 140 (t(32) = 2.09, P = 0.0450) and 196 (t(34) = 2.17, P = 0.0371) using a repeated measures analysis of variance having a significant treatment by time interaction (degrees of freedom were rounded for display purposes). Overall, the optical density readings for heat-treated samples were higher than non-heat-treated samples