Risk Factors associated with the Incidence of Foal Mortality in a Pregnant Mare Urine Herd

The purpose of this study was to determine the incidence of neonatal mortality in a large pregnant mare urine (PMU) herd and determine what risk factors were involved in foal mortality. For a 6 week period between April 18, 1994 and May 31, 1994, 334 foals were born, of which 74 died before reaching 10 days of age, giving an overall mortality of 22% for this period. Seventy four percent of the foal deaths occurred within 48 hours of parturition. The major causes of foal mortality included starvation/exposure 27%, septicemia 26%, and dystocia 20%. Weekly incidence varied significantly ranging from 67% for week 1 to 14% for week 5 (p< 0.01). Other risk factors which were associated with foal death included failure of passive transfer (p< 0.0001), poor mothering ability (p< 0.0001), the presence of dystocia (p< 0.0001), low birth weight (p< 0.05), lack of rainfall (p< 0.01), and low temperatures (p< 0.1). The effect of sire, mare age, mare body condition score and foal sex were not significant risk factors for foal survival (p> 0.1). Further studies are required to determine if changing management procedures will be effective in reducing the incidence of neonatal foal mortality in PMU herds