Preliminary Observations of the Effect of Garlic on Egg Shedding in Horses Naturally Infected by Intestinal Strongyles

Intestinal strongyles are the most common endoparasites of horses, and anthelmintic treatments are the main strategy to control these nematodes. However, the development of anthelmintic resistance has led to a decreased efficacy of synthetic drugs, and for this reason, there is a growing interest in alternative control strategies as the use of medicinal plants. The aim of the present study was to determine the in vivo efficacy of garlic (Allium sativum) in horses naturally infected by intestinal strongyles. The field trial was conducted in a horse trotter farm in Southern Italy. Fifteen mares were selected based on fecal egg count >200 eggs per gram and allocated into three groups of five animals: fresh garlic group (FG group), animals received 40 g of fresh crushed garlic once daily for 15 days; dry garlic group (DG group), animals received 40 g of commercial dry garlic flakes food supplement once daily for 15 days; and control group (C group), not treated. Two weeks after the first administration of garlic, fecal egg count reduction test showed failure of garlic to reduce intestinal strongyles egg shedding (−11.7% and −19.4% for FG and DG groups, respectively). Red blood cell count values were in the normal ranges over the entire period of garlic administration. In our study model, the oral administration of garlic formulations has no effect on reducing the egg shedding of intestinal strongyles, and the garlic supplementation over a short period of time is not responsible for hematological changes in horses.