Technical Abstract: In this study, 35 horses were infected with 1000, 5000, or 10,000 T. spiralis muscle larvae and the course of infection was followed for 1 year. Larval burdens in selected muscles, the condition and infectivity of larvae in tissue, and the serological response of infected horses were assessed. The results of the study demonstrated that T. spiralis establishes infection in horses in a dose dependent manner. Low dose infections may be detected by an increase in parasite-specific serum antibodies despite an inability to recover parasites. Anti-Trichinella IgG antibodies peaked between weeks 6-10 post-inoculation and declined to pre-inoculation levels by weeks 24-26. Viable, infective larvae persist in horse musculature for at least 12 months, and exhibit no reduction in muscle burdens over this period. Given the lack of a detectable serological response by 26 weeks p.i. despite the persistence of infective muscle larvae, direct methods of detection are the only methods suitable for both meat inspection and epidemiological studies of Trichinella infection in the horse.