This is the article postprint. The final publisher PDF is available at the Journal of Veterinary Behavior website:


Esophageal obstruction or “choke” is a relatively common occurrence in the equine industry. It often results from improper mastication, consuming feed too quickly, dehydration or a decrease in saliva production. Esophageal obstruction is a medical emergency during which a horse cannot dislodge a bolus of feed from the esophagus and must wait for human intervention or for the block to be softened and moved by peristalsis. This condition may result in the formation of ulcers, esophageal rupture, aspiration pneumonia, and possibly death. Grazing muzzles have been shown to slow the rate of forage intake. We hypothesized that grazing muzzles could also be used to decrease the rate of pelleted feed intake and so possibly reduce the risk of equine esophageal obstruction in horses fed large meals of pelleted feed. The objective of this research was to compare the rate of pelleted feed intake for horses wearing grazing muzzles to those wearing no muzzle. Utilizing a crossover design, horses were randomly assigned to three groups with each horse receiving each treatment. Treatments were as follows: No Muzzle (NM), Easy Breath Grazing Muzzle (EBGM), or Tough 1 Nylon Grazing Muzzle (TNGM). Eight adult stock-type horses age 5 ±1 years, were offered 2.27 kg of pelleted concentrate to consume in a 10-minute period once daily. The study was comprised of three periods (5 days each) with a two-day resting period between each. Horses were weighed daily and no significant change in bodyweight was observed. Data for daily intake were analyzed using the PROC MIXED procedure of SAS with significance established at P < 0.05. Both the EBGM and the TNGM reduced rate of intake (P < 0.05) during a 10-minute feeding interval as compared with NM. The findings of this study revealed that grazing muzzles may be a viable option to reduce the rate of intake of pelleted feed, which may benefit horses susceptible to choke as a 31 result of rapid feed ingestion.