Use of stored equine colostrum for the treatment of foals perceived to be at risk for failure of transfer of passive immunity.

OBJECTIVE-To assess the use of stored equine colostrum for the treatment of foals perceived to be at risk for failure of transfer of passive immunity (FTPI). DESIGN-Cohort study. ANIMALS-232 Thoroughbred foals and 191 Thoroughbred mares (41 mares gave birth to 1 foal on 2 occasions). PROCEDURES-Postpartum, presuckle colostrum samples were collected from mares; samples with a colostral refractive index (cRI) > or = 23% were frozen (-20 degrees C [-4 degrees F]) and stored for > or = 7 days but < 2 years. Foals of dams that produced colostrum with a cRI value < 20% were treated with > or = 300 mL of stored colostrum that was thawed and administered via nasogastric tube on 1 to 4 occasions within 6 hours after parturition. Serum samples were obtained from colostrum-treated and nontreated foals 24 hours after treatment or suckling, respectively, for determination of serum IgG (sIgG) concentration. RESULTS-8 foals and their respective dams were excluded from the analyses. For the remaining 30 treated and 194 nontreated foals, mean +/- SD sIgG concentration was 1,597 +/- 574 mg/dL. Thirteen (5.8%) foals had sIgG concentrations < 800 mg/dL, of which 1 (0.4%) had an sIgG concentration < 400 mg/dL. Nine of these foals had suckled mares producing colostrum with a cRI value > or = 20%, and 2 foals had been treated with stored colostrum. CONCLUSIONS AND CLINICAL RELEVANCE-Treatment with stored colostrum appeared to be effective for prevention of FTPI in at-risk foals. However, foals were still at risk for FTPI despite suckling of or treatment with colostrum with adequate cRI values.