Short‐Term Daily Oral Administration of Cannabidiol Does Not Impact Rebound Tonometry Intraocular Pressure or Schirmer Tear Test Values in Healthy Adult Horses

ABSTRACT Objective To assess the effect of orally administered cannabidiol (CBD) on TonoVet measured intraocular pressure (IOP) and Schirmer tear test I (STT) in horses. Animal Studied Horse. Procedure This was a masked, randomized, balanced cross‐over study of six healthy adult horses. Horses were randomly assigned and received 3 mg/kg CBD in sesame oil or volume matched placebo by mouth once daily for three days. Baseline and daily 4‐, 12‐, and 24‐h post treatment IOPs were measured in triplicate without sedation or eyelid akinesia. Baseline and 24‐h post final (day 3) treatment STTs were measured without sedation or eyelid akinesia. After a five‐week washout period, horses received the alternate treatment, and measurements were repeated as above. Results Overall, there were no clinically relevant differences in IOP with CBD administration. Irrespective of treatment, IOPs were significantly higher in the second treatment period ( p = 0.009). There were no differences in STT with CBD administration. Conclusion Oral CBD administration in healthy horses does not impact rebound tonometry IOP or STT measurements.