Urinary excretion of theobromine in horses given contaminated pelleted food.

This study details a method to measure the amount of theobromine in cocoa husks, pelleted food, and horse urine, and its detection time post intake. This resulted from horses consuming feed with 38.4 mg of theobromine twice daily over a 2.5 days period. The key findings indicate the theobromine concentration fell below the threshold value 2 micrograms/ml after two days from the last intake.

Research Method

• The researchers used a high pressure liquid chromatographic (HPLC) method to measure the theobromine content in materials such as cocoa husks, pelleted food, and horse urine. HPLC is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture.
• The method was sensitive enough to detect theobromine concentrations as low as 500 ng/ml from a starting sample of 2 ml of urine.

Administration of Theobromine

• In the experiment, horses were given feed containing 38.4 mg of theobromine twice daily over a period of two and a half days.
• Following the last intake of theobromine-infused feed, two days were needed before theobromine concentrations in the horse’s urine fell below the threshold value of 2 micrograms/ml.

Peak Excretion Rate and Urinary Flow

• It was observed that the time for peak excretion rate, or the point when the theobromine was most heavily present in the urine, varied from 2 to 12 hours after the last administration of theobromine-infused feed.
• The researchers also noted that the rate of theobromine excretion seemed to be dependent on the urinary flow.

Presence of Theobromine in Plasma

• After this method of administration, theobromine could not be detected in the horse’s blood plasma.