Association of maximum voluntary dietary intake of freeze-dried garlic with Heinz body anemia in horses.
OBJECTIVE
To characterize hematologic and clinical consequences of chronic dietary consumption of freeze-dried garlic at maximum voluntary intake in horses.


METHODS
4 healthy sex- and age-matched horses.


METHODS
An initial garlic dose (0.05 g/kg, twice daily) was fed to 2 horses in a molasses carrier as part of their normal ration and was gradually increased to maximum voluntary intake (0.25 g/kg, twice daily) over 41 days. Dietary supplementation then continued for a total of 71 days. Two control horses were fed molasses with no garlic with their ration. Blood samples were collected weekly and analyzed for hematologic and biochemical changes, including the presence of Heinz bodies. Recovery of affected blood values was followed for 5 weeks after termination of dietary supplementation with garlic.


RESULTS
At a daily dose of > 0.2 g/kg, horses fed garlic developed hematologic and biochemical indications of Heinz body anemia, as characterized by increases in Heinz body score (HBS), mean corpuscular volume (MCV), mean corpuscular hemoglobin, platelet count, and serum unconjugated and total bilirubin concentrations and decreases in RBC count, blood hemoglobin concentration, mean corpuscular hemoglobin concentration, and serum haptoglobin concentration. Recovery from anemia was largely complete within 5 weeks after termination of dietary supplementation with garlic. Heinz body score and MCV remained high at the end of the 5-week recovery period.


CONCLUSIONS
Horses will voluntarily consume sufficient quantities of garlic to cause Heinz body anemia. The potential for garlic toxicosis exists when horses are chronically fed garlic. Further study is required to determine the safe dietary dose of garlic in horses.
Pearson
Wendy
W
Department of Animal and Poultry Science, University of Guelph, Guelph, ON, N1G 2W1 Canada.
Boermans
Herman J
HJ
Bettger
William J
WJ
McBride
Brian W
BW
Lindinger
Michael I
MI
D000704:Analysis of Variance; D000740:Anemia / Q000139:chemically induced / Q000662:veterinary*; D000818:Animals; D001774:Blood Chemical Analysis / Q000662:veterinary; D019587:Dietary Supplements / Q000633:toxicity*; D004220:Disulfides; D004906:Erythrocyte Count / Q000662:veterinary; D005737:Garlic / Q000737:chemistry / Q000633:toxicity*; D006366:Heinz Bodies / Q000473:pathology*; D006454:Hemoglobins / Q000378:metabolism; D006734:Horse Diseases / Q000139:chemically induced*; D006736:Horses; D013441:Sulfinic Acids / Q000032:analysis
D004220:Disulfides; D006454:Hemoglobins; D013441:Sulfinic Acids; C006452:allicin