Gestation Length is Associated With Early-Life Limb Deformities in Foals

Gestation Length is Associated With Early-Life Limb Deformities in Thoroughbred Foals
J Equine Vet Sci. 2023 Oct;129:104896. doi: 10.1016/j.jevs.2023.104896. Epub 2023 Aug 2.
Authors
Rebecca Mouncey 1 , Juan Carlos Arango-Sabogal 2 , Amanda M de Mestre 3 , Kristien Verheyen 4
Affiliations

1 Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, UK. Electronic address: rmouncey18@rvc.ac.uk.
2 Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, UK; Département de Pathologie et Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, Canada.
3 Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, UK; Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, USA.
4 Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, UK.

PMID: 37541603
DOI: 10.1016/j.jevs.2023.104896

Abstract

Flexural and angular limb deformities (LD) are an important cause of early-life morbidity and mortality/euthanasia in Thoroughbred foals. The majority are congenital in origin but, to date, their precise aetiology is poorly understood. We hypothesized that maternal- and pregnancy-level factors, particularly those with potential to influence in-utero growth and development, could play an important role. The aim of this study was therefore to investigate associations between such factors and early-life LD in Thoroughbred foals. A birth cohort was established on seven farms across the United Kingdom and Ireland and details of veterinary interventions for LD in foals in the first six months of life prospectively recorded. Details of dams’ signalment, breeding history and reproductive and veterinary history in the breeding season(s) of interest were retrieved retrospectively from stud farm and veterinary records. Associations between mare- and pregnancy-level factors and LD in offspring were assessed using multivariable logistic regression. Records were available for 275 pregnancies in 235 mares, over two breeding seasons. Pregnancies resulted in the birth of 272 live foals, 21% of which (n = 57/272, 95% CI, 16-26) required veterinary intervention for LD in the first six months of life. Odds of LD decreased by 4% per day increase in gestation length between 314 and 381 days (OR 0.96, 95% CI, 0.93-0.99, P = .01). Longer gestation length appears to reduce the odds of early-life LD, including within the normal range of gestation length for Thoroughbred foals. Further work is required to elucidate biological mechanisms behind this association.

Keywords: Equine; Foal; Gestation; Limb deformity; Thoroughbred.