PSXV-15 - Effect of Supplemental Garlic on the Incidence of Heinz Body Anemia in Non-working Horses

Abstract: Garlic (Allium sativum) has been historically used as a fly and pest control for horses, a practice that continues today. Recent research has shown garlic supplementation may cause Heinz body anemia in horses. The purpose of this study was to evaluate the incidence of Heinz body anemia in horses supplemented with incremental amounts of powdered garlic. The study included 12 horses divided into 4 groups (n=3), with horse serving as the experimental unit. Supplementation groups included: Control (0.0 g garlic/kg BW and 14.3 g molasses) and 3 supplementation rates: Low (0.0625 g garlic/kg BW and 14.3 g molasses), Medium (0.125 g garlic/kg BW and 14.3 g molasses), and High (0.1875 g garlic/kg BW and 14.3 g molasses) that were fed daily for 74 days. Horses were maintained on dormant tall fescue pasture and had ad libitum access to medium quality tall fescue hay throughout the study. Blood samples (jugular venipuncture) and weights were taken on day 0, 25, 50, and 74. Data were analyzed using Proc Mixed (SAS 9.4) for a completely randomized design, α = 0.05. Garlic supplementation reduced red blood cell count (P = 0.028) compared with Control and lymphocyte count (P = 0.046) showed a quadratic response to supplementation rate, with Low having the greatest lymphocyte count. A trend was noted for white blood cell count (P = 0.090) and hemoglobin count (P = 0.074) with garlic supplementation. Heinz body count (P = 0.406) was not affected by garlic supplementation. Results are interpreted to mean that garlic supplementation did not induce Heinz body anemia in horses; however, other blood constituents, including red blood cell and lymphocyte counts, were affected. Horses in the study were non-working, further research would be needed to evaluate any potential health impacts these variations in blood constituent concentrations would have in working horses.