Use of a Qualitative Horse-Side Test to Measure Serum Amyloid A in Mares With Experimentally Induced Ascending Placentitis

• A commercial lateral flow device (LFD) for determination of serum amyloid A concentrations was evaluated in mares with experimental placentitis.
• Serum amyloid A concentrations measured by the LFD were compared with a quantitative immunoassay.
• Serum amyloid A concentrations were elevated in mares with experimental placentitis beginning at 6 days before abortion as measured by both the LFD and the quantitative immunoassay.
• Serum amyloid A concentrations determined by the LFD were moderately but significantly correlated to those measured by quantitative immunoassay.

The objectives of this study were to assess (1) changes in serum amyloid A (SAA) detected by a lateral flow device (LFD) in mares with experimental placentitis and (2) to assess the correlation of this assay with a quantitative immunoassay. Horse mares carrying normal pregnancies were assigned to a control group (n = 12) and to a group with experimentally induced ascending placentitis (n = 13). Blood samples were obtained immediately before inoculation and/or initial sampling for control mares and then daily for 12 days or until abortion. Concentration of SAA was analyzed using a turbidometric immunoassay. Retrospectively, samples −9, −6, −3, and 0 days from abortion (DFA) were analyzed. Day 0 was defined as the day of abortion for mares in the placentitis group and the last sampling day for mares in the control group. Based on the LFD results, there were significant differences between mares in the control group and mares in the group with experimentally induced placentitis (P < .0001). There was a progressive increase in SAA from −6 to 0 DFA determined by the LFD. There were no significant differences among examiners (P > .05). The results obtained using the commercial LFD were moderately correlated (ρ = 0.51; P < .001) with the concentrations of SAA determined by the turbidometric assay. Five of 91 LFDs (i.e., 5.5%) failed to provide any reading. The LFD for determination of SAA appears to be a useful tool for quick assessment of whether inflammation is present; however, quantitative evaluation may still be warranted.