A 12-year retrospective study of equine abortion in Michigan.

This research article presents a 12-year retrospective study (1985-1996) conducted in Michigan on the causes of equine (horse) abortions or stillbirths to understand the factors contributing to such instances.

Study Overview

• The researchers sought to investigate the reasons leading to equine abortions, emphasizing that historically, determining the cause has been challenging, with up to 16-16.9% of cases leaving the reason unresolved.
• Existing equine abortion data primarily comes from the extensive analysis of the Kentucky bluegrass region and Newmarket, England’s equine populations. However, given the regional and population variations between Kentucky, England, and Michigan, the study aims to add unique value in understanding the abortion cases specific to Michigan.
• The investigation involved studying the abortion submissions to the Animal Health Diagnostic Laboratory (AHDL) at Michigan State University.

Data Collection and Analysis

• The study included 290 cases of equine fetal submissions, of either aborted or stillborn foals, from February 1985 through June 1996.
• Majority of the submissions were from Michigan, except one from Missouri, two from northern Ohio, and three from western Pennsylvania.
• The recorded data incorporated a range of parameters like geographic distribution, equine breeds, sex, gestational age, and whenever available, diagnostic findings.

Study Observations

• The study represented 22 equine breeds, indicating a diverse sample population for the research.
• The sex of the foals was well-distributed with 123 males, 108 females, and 59 foals without a sex descriptor.
• Most submissions were recorded between November and May, with the heaviest prevalence during January to March. The study suggests that this period may be crucial in preventing equine abortions.
• The gestation ages at the time of the abortion or stillbirth varied greatly, but the majority of abortions occurred between 270 and 300 days of gestation.