Foal Heat and Contaminant Bacteria5
SETTLE decreases postpartum intrauterine
bacterial infections and increases conception rates at the foal
Although the foal heat in mares is fertile, it is associated with a
high incidence of late embryonic mortality. This is attributed to the
presence of microbial contaminants associated with
incomplete uterine involution at the foal heat.
Eighty-nine pregnant mares were identified at the Tandil military
equestrian facility and randomly divided into two groups. All mares
were treated the day after foaling with either a single dose of
intravenous SETTLE or placebo. Twenty-five mares were sampled for
intrauterine bacteria and cytology at the time of treatment and seven
days later (n[SETTLE]=13, n[placebo]=12). Mares were bred at the foal
heat to stallions of known high fertility.
There was no difference in bacterial contaminants for mares in
either group on the day after foaling, with
and E. coli being the most common contaminants. Sixteen different
organisms were cultured from 12/13 mares in the SETTLE group and 16
from 12/12 in the placebo group. Seven days later, only two mares in
the SETTLE group had mild bacterial infections, whereas nine mares in
the placebo group were still infected (p<0.001).
The overall reduction in total bacterial colony forming units (cfu)
was 99% for SETTLE and 45% for placebo. Similarly, total PMN counts
were reduced by 92% in SETTLE treated mares compared with 59% in the
placebo treated animals. At day seven, 11/12 SETTLE mares had <5 PMN/400x
whereas the placebo group had only 2/12 animals with <5 PMN/400x.
Eleven of 12 sampled mares in the SETTLE group ovulated at the foal
heat and were bred. Only 6/12 placebo-treated, sampled mares ovulated
and were bred within three weeks of foaling.
Results for all foal heat breeding pregnancies were 28/43 (65%) for
SETTLE treated mares and 9/38 (24%) for the placebo treated group
With large numbers of mares and indifferent mare management, this
facility has historically obtained poor pregnancy results (average
pregnancies / cycle less than 25%) when compared to well-run broodmare
farms. That being said, this facility offered a single site, with
numerous endometritis susceptible mares available for study and the
foal heat breeding results obtained were statistically significant