A second-generation, point-of-care immunoassay provided improved detection ofandantibodies in PCR-positive dogs naturally infected withorspecies.

Abstract

A validated second-generation SNAP 4Dx Plus (Idexx) incorporates new peptides for improved detection of antibodies againstandtick-borne pathogens in dogs. We compared the first- and second-generation SNAP 4Dx Plus using dogs naturally infected withorspecies, or dogs seroreactive by anindirect fluorescent antibody test (IFAT). The second-generation immunoassay was more sensitive than the first-generation for dogs infected with(51.1% and 29.2%, respectively),(63.6% and 35.3%, respectively),(96.2% and 88.3%, respectively), or(73.7% and 70.8%, respectively), and for dogs seroreactive byIFAT (87.3% and 83.9%, respectively). The second-generation immunoassay detected significantly more- or-infected dogs that were(&#x2009;<&#x2009;0.001) or(&#x2009;=&#x2009;0.031) seroreactive, respectively, than did the first-generation test. Whenseroreactivity byIFAT and both immunoassays was compared, significantly more-infected dogs were seroreactive byIFAT than the first-generation (&#x2009;=&#x2009;0.006) but not the second-generation (&#x2009;=&#x2009;0.125) immunoassay. Significantly more-infected dogs were seroreactive by the first- (&#x2009;=&#x2009;0.011) and second-generation (&#x2009;=&#x2009;0.049) immunoassays than theIFAT. Medical records available for 7 dogs that wereseroreactive by the second-generation but not the first-generation immunoassay revealed case management decisions that might have been different with an immediate anaplasmosis diagnosis, including earlier doxycycline therapy and less hospitalization. The second-generation SNAP 4Dx Plus test offered improved serologic detection ofandin naturally infected dogs.