Factors associated with long‐term athletic outcome in Thoroughbred neonates admitted to an intensive care unit

Abstract

Summary Background Limited information exists on the long‐term outcome of foals that survive following hospitalisation for disease as a neonate. Significant financial investment is required to raise foals to racing age, therefore improved understanding of factors that affect long‐term outcome and future athletic performance is important. Objectives To analyse racing performance in Thoroughbred foals hospitalised as neonates, compared with their maternal siblings and to determine factors associated with failure to race and racing performance. Study design Retrospective cohort study. Methods Medical records of Thoroughbred foals admitted to a neonatal intensive care unit between 1982 and 2008 were reviewed. Surviving foals of registered mares were included. Data including the foal's primary and concurrent diseases were extracted from the medical record. Racing records for foals and maternal siblings were evaluated. Multivariable logistic regression was used to identify disorders associated with failure to race and decreased racing performance. Results Two‐hundred and sixty‐nine of 454 previously hospitalised foals (59%) raced. Sixty‐eight percent (269/394) of registered foals raced, compared with 79% (697/880) of registered siblings. Foals with prematurity/dysmaturity (P = 0.002) and those with orthopaedic disease (P = 0.007) were significantly less likely to race than their siblings. Premature/dysmature foals also had significantly fewer starts and wins and lower earnings than siblings. Foals with orthopaedic disorders had a lower percentage of wins, relative to their siblings. There was no significant association between racing performance and other disease categories. Main limitations Small sample size in some disease categories and retrospective nature of study. Conclusions Foals hospitalised due to prematurity/dysmaturity or orthopaedic disorders were less likely to race than their maternal siblings and those that did race had decreased performance.

The effect of neonatal dysphagia on subsequent racing performance in Standardbred horses

“…(Previous statistical analysis of their physical exam and clinical pathology data had revealed no significant difference between these two groups of foals) 7 . Some studies examining the effects of a neonatal disease on subsequent athleticism have used maternal siblings as controls 9,10 . While this was desirable, it was not possible to match every dysphagic foal with an unaffected sibling control during the study period.…”

Clinical insights: Recent development in equine neonatology and foal medicine (2017–2019)

“…In this study, of the 454 hospitalised foals, 394 foals were registered with the US Jockey Club which provided racing data to compare with 880 registered siblings that were never hospitalised. Previously hospitalised foals were significantly less likely to race with 68% of hospitalised registered foals racing as compared to 79% of their 880 siblings . In addition, hospitalised foals that were premature/dysmature and those with orthopaedic disease were significantly less likely to race than their siblings.…”

“…In this retrospective study, 269 of 454 hospitalised foals (59%) survived to discharge and subsequently raced. Factors associated with failure to race that were retained in the multivariable model included prematurity/dysmaturity, noninfectious orthopaedic disease and female sex . It is not surprising that premature/dysmature foals were less likely to race because of the strong association with incomplete ossification of the cuboidal bones .…”

“…Numerous studies have already documented survival to discharge of hospitalised equine neonates, but minimal information is available with regard to the long‐term outcome and athletic performance of ill neonatal foals that survive to hospital discharge . Because of the significant financial and emotional investment in the care of ill foals, a recent publication expanded the time‐line for outcome and examined factors associated with long‐term athletic performance in hospitalised Thoroughbred neonates . In this retrospective study, 269 of 454 hospitalised foals (59%) survived to discharge and subsequently raced.…”

“…In addition, hospitalised foals that were premature/dysmature and those with orthopaedic disease were significantly less likely to race than their siblings. Further details with regard to racing performance between hospitalised foals and siblings documented that hospitalised foals that went on to race had a lower percentage of wins, adjusted earnings and standard starts index (SSI) as compared to their siblings .…”