title: Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.
abstract: BACKGROUND
  The birthweight of Thoroughbred foals has increased in recent years. It is unknown whether this is associated with increased broodmare obesity or endocrine dysfunction.
  
  
  OBJECTIVE
  To determine insulin, leptin and triglyceride concentrations in obese and non-obese Thoroughbred mares throughout gestation and to investigate their association with foal birthweight.
  
  
  METHODS
  Prospective, cohort study.
  
  
  METHODS
  Fifty-seven pregnant Thoroughbred mares were included in the study. From 40 days post-breeding, body condition score (BCS), weight and venous blood samples were obtained every 60 days throughout gestation. Feed was withheld for 6 h before blood sampling. Serum/plasma insulin, leptin and triglyceride concentrations were measured using validated/standard methods. Foal birthweight was recorded. Association of hormone or triglyceride concentration with time, BCS and birthweight were analysed using a linear mixed effects model. A Pearson correlation co-efficient was calculated between hormone or triglyceride concentration, BCS and birthweight.
  
  
  RESULTS
  Serum insulin concentrations were significantly greater (P<0.05) at 0-59 days compared with 240-299 days and at 60-119 days compared with 180-359 days gestation. 55% of mares had BCS ≥ 7. There was 1.5% incidence of fasting hyperinsulinaemia throughout gestation and no association of fasting insulin concentration with BCS. Leptin concentration was significantly (P<0.0001) greater at 180-239 days compared with all other time points and was significantly (r = 0.29, P<0.0003) correlated with BCS. Triglyceride concentration was significantly (P<0.02) greater at 240-299 days compared with earlier time points but was not associated with BCS. Foal birthweight was significantly positively correlated with BCS (r = 0.13, P<0.001) and inversely correlated with leptin concentration at 60-119 days and 240-299 days gestation (r = -0.64, P<0.05).
  
  
  CONCLUSIONS
  Mare BCS correlated with foal birthweight such that obese mares had heavier foals. Significant fasting hyperinsulinaemia was not identified in this population. Increased leptin concentration in early and late gestation was associated with decreased foal birthweight and may be useful to predict foal birthweight. Ethical animal research: Informed client consent was obtained for all animals used in the study.
  
  
  BACKGROUND
  Private donor. Competing interests: None declared.
authors.affiliation: Royal Veterinary College, London.
authors.forename: S
authors.initials: S
authors.lastname: Smith
authors.affiliation: Rossdales Equine Hospital, Exning, Newmarket, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Marr
authors.affiliation: Royal Veterinary College, London.
authors.forename: N J
authors.initials: NJ
authors.lastname: Menzies-Gow