A Murine model of Mare Reproductive Loss Syndrome

Abstract

Background Mare reproductive loss syndrome (MRLS), first reported in 2001 from Kentucky, has caused thousands of equine abortions and estimated $1/2 billion in economic loss. MRLS affects mare after ingesting caterpillars. This may result in irritation, lesions and increased gut permeability. The á hemolytics Strep. sp and Actinobacillus sp, present in normal digestive tract, have been isolated in field and experimental aborted cases. Bacterial replication in the fetal fluids is likely to compromise the fetus and causes abortion. A murine model would facilitate the study of MRLS. Methods Seventy programmed pregnant ICR mice were injected via tail vein or IP with 1X104–8 CFU Strep. cricetus and/or Actinobacillus sp isolated from aborted fetus. Control animals received saline. Results Injected dams did not develop any clinical symptoms. There were sporadic cases of aborted fetuses that correlated with the amount of bacteria. No significant difference was noted between the number of delivered pups and their weight between groups. Day old pups when injected with bacteria developed focal abscess, lost weight but recovered after one week. However, SRA/CD36 deficient pregnant mice developed 100% fetal death and abortion 24–74h after bacterial injection. We conclude that deficient mice may serve as a pivotal model to study MRLS.