A diagnostic evaluation of real-time PCR, fluorescent antibody and microscopic agglutination tests in cases of equine leptospiral abortion.
Authors: Erol E, Jackson C B, Steinman M, Meares K, Donahoe J, Kelly N, Locke S, Smith J L, Carter C N
Journal: Equine veterinary journal
Summary
# Editorial Summary Leptospirosis remains a significant cause of equine abortion, yet diagnostic confirmation has traditionally relied on serological and microscopic methods with varying sensitivity. Erol and colleagues conducted a comparative evaluation of real-time PCR (targeting the LipL32 gene), fluorescent antibody testing (FAT) and microscopic agglutination testing (MAT) across fetal tissues and maternal serum from 339 necropsied equine fetuses to determine which diagnostic approach most reliably identifies leptospiral abortion. Real-time PCR demonstrated superior detection, identifying all 21 confirmed leptospiral cases compared with 19 for MAT and 18 for FAT, whilst placental and renal specimens yielded the most reliable results across methods—though kidney proved optimal for FAT analysis. Of note, serovar Pomona predominated in positive cases with titres ranging from 1:100 to 1:204,800 in fetal heart blood, with minimal cross-reactivity to serovar Grippotyphosa. For practitioners investigating equine abortions, particularly during the winter months when cases cluster, real-time PCR offers definitive diagnostic sensitivity; however, MAT remains essential for precise serovar identification, which can inform herd management, vaccination strategy and epidemiological tracking.
Read the full abstract on PubMed
Practical Takeaways
- •Real-time PCR targeting LipL32 is the most sensitive diagnostic test for equine leptospiral abortion and should be considered the gold standard method
- •Continue using MAT in clinical cases alongside PCR for accurate serovar identification, which has epidemiological and herd management implications
- •Heightened clinical suspicion for leptospiral abortion is warranted during January–February when 62% of cases occur; ensure appropriate tissue sampling (placenta and kidney) for diagnostic confirmation
Key Findings
- •Real-time PCR detected all 21 leptospiral abortion cases (100%), compared to 19/21 (90.5%) for MAT and 18/21 (85.7%) for FAT
- •Placenta and kidney yielded comparable cycle threshold values on real-time PCR, but kidney was superior for FAT diagnosis
- •Leptospiral abortions showed strong seasonal clustering with 13 of 21 cases (61.9%) occurring in January and February
- •Serovar Pomona was predominant in all MAT-positive fetal heart blood cases with titres ranging 1:100 to 1:204,800, with minimal cross-reactivity to serovar Grippotyphosa