Effects of a Streptococcus equi infection--mediated nutritional insult during mid-gestation in primiparous Thoroughbred fillies. Part 1: placental and fetal development.
Authors: Wilsher S, Allen W R
Journal: Equine veterinary journal
Summary
# Editorial Summary During mid-gestation, the equine placenta undergoes rapid proliferative growth, making this period particularly vulnerable to nutritional disruption; Wilsher and Allen's 2006 investigation examined how two planes of nutrition and an unexpected *Streptococcus equi* infection affected placental development and fetal outcomes in twenty maiden Thoroughbred fillies. Whilst controlled high versus moderate feeding throughout pregnancy had no significant impact on placental or fetal growth parameters, the acute infection-mediated weight loss experienced by all mares in mid-gestation produced measurable morphological changes to the allantochorion and resulted in reduced foal birthweights. The findings suggest that maternal bodyweight gain per se does not trigger compensatory nutrient partitioning away from the developing fetus, but transient weight loss during the critical mid-gestational window impairs placental efficiency with lasting consequences for fetal growth. For practitioners managing pregnant mares, this work underscores the importance of preventing or rapidly treating systemic infections during mid-gestation, as the associated metabolic stress and feed intake reduction pose greater risk to pregnancy outcome than does controlled higher plane nutrition during other periods of gestation.
Read the full abstract on PubMed
Practical Takeaways
- •Acute maternal infections causing significant weight loss during mid-gestation can compromise placental development and reduce foal birthweight; monitor pregnant mares closely during illness and consider supportive nutrition.
- •Overfeeding early-pregnant maiden mares does not improve foal outcomes, so tailor nutrition based on body condition scoring rather than maximizing weight gain.
- •Clinicians should counsel clients that maternal systemic infections during pregnancy may have lasting effects on fetal growth despite apparent recovery, and plan for potential complications at foaling.
Key Findings
- •High plane of nutrition resulted in significantly greater maternal bodyweight gains during gestation compared to moderate nutrition, but did not enhance placental or fetal growth parameters.
- •Mid-gestation infection with Streptococcus equi caused transient weight loss and resulted in morphological changes to the allantochorion and reduced foal birthweight.
- •Sudden weight loss during the proliferative phase of placental development (mid-gestation) had detrimental effects on placental structure that persisted to term.
- •Excessive maternal weight gain during pregnancy does not result in preferential nutrient partitioning to the dam at the expense of the fetus in maiden Thoroughbred fillies.