Factors associated with outcome in foals with neonatal isoerythrolysis (72 cases, 1988-2003)

Neonatal foals with isoerythrolysis (NI) often die, but the risk factors for death have not been identified.

To identify factors associated with outcome in foals with NI and to identify factors associated with death from liver failure or kernicterus in the same population.

Seventy-two foals with NI examined at referral institutions.

Retrospective case series. Information on signalment, clinical examination findings, laboratory testing, treatment, complications, outcome, and necropsy results were obtained.

The overall survival rate was 75% (54 of 72). Liver failure (n=7), kernicterus (n=6), and complications related to bacterial sepsis (n=3) were the 3 most common reasons for death or euthanasia. The number of transfusions with blood products was the factor most strongly associated with nonsurvival in a multivariate logistic regression model. The odds of liver failure developing in foals receiving a total volume of blood products >or= 4.0 L were 19.5 (95% confidence intervals [CI]: 2.13-178) times higher than that of foals receiving a lower volume (P= .009). The odds of kernicterus developing in foals with a total bilirubin >or= 27.0 mg/dL were 17.0 (95% CI: 1.77-165) times higher than that of foals with a lower total bilirubin (P= .014).

Development of liver failure, kernicterus, and complications related to bacterial sepsis are the most common causes of death in foals with NI. Foals administered a large volume of blood products are at greater risk for developing liver failure.