Anti-strongyle activity of a propylene glycol-glycerol formal formulation of ivermectin in horses (mares).

ABSTRACT

Four groups of 10 horses (mares) each were treated with a 1% solution of ivermectin (200 micrograms/kg of body weight) in a propylene glycol-glycerol formal base orally, a 1% solution of ivermectin (200 micrograms/kg) in a propylene glycol-glycerol formal base via nasogastric tube, a 1.87% paste of ivermectin (200 micrograms/kg) orally, or a 22.7% paste of oxibendazole (10 mg/kg) orally. Fecal examinations were done before treatment and on posttreatment days (PTD) 14, 28, 42, 56, and 70. Strongyle egg per gram counts and sugar flotation fecal examinations were performed. Results of fecal examinations before treatment were similar in all horses. All horses treated with ivermectin had similar percentages of reductions in mean strongyle egg per gram counts after treatment; 100% on PTD 14, 28, and 56 and 93.4% to 98.7% on PTD 70. All ivermectin treatment groups had 0 horses detected as passing strongyle eggs on PTD 14 and 28, 0 to 2 on PTD 42, 3 to 5 on PTD 56, and 8 to 9 on PTD 70. Horses treated with oxibendazole had 99.9%, 99.7%, 92.9% 78.6%, and 54.5% reductions in mean strongyle egg per gram counts and 5, 7, 8, 9, and 9 horses detected as passing strongyle eggs on PTD 14, 28, 42, 56, and 70, respectively. Adverse reactions to treatment were not observed.