Plasma l‐indospicine and 3‐nitropropionic acid in ponies fed creeping indigo: Comparison with results from an episode of presumptive creeping indigo toxicosis

Background Creeping indigo (Indigofera spicata) toxicosis is an emerging problem among horses in Florida and bordering states. Objectives To quantify the putative toxins l‐indospicine (IND) and 3‐nitropropionic acid (NPA) in creeping indigo collected from multiple sites and to measure plasma toxin concentrations in ponies fed creeping indigo and horses with presumptive creeping indigo toxicosis. Study design Experimental descriptive study with descriptive observational field investigation. Methods Air‐dried creeping indigo was assayed for IND and NPA content. Five ponies were fed chopped creeping indigo containing 1 mg/kg/day of IND and trace amounts of NPA for 5 days, then observed for 28 days. Blood samples from these ponies and from horses involved in a presumptive creeping indigo toxicosis were assayed for IND and NPA. Results IND in creeping indigo plants was 0.4‐3.5 mg/g dry matter whereas NPA was