Low pH Levels and Stereotypies

Stereotypies are repetitive behaviors such as weaving or cribbing. They are common in horses kept in stalls the majority of the time, but are not unknown in pastured horses. Some research has shown a link between stereotypic behaviors and a typically low hindgut pH levels. Because the antibiotic virginiamycin has been shown to increase hindgut pH in horses, it was theorized that administering virginiamycin might ease discomfort and allow horses to reduce stereotypies.

However, the theory was not supported by results of a study at the University of Sydney. When virginiamycin was given to six weavers, five cribbers, and six control horses, no significant effects were seen on cribbing, weaving, heart rate, digestibility of feed, blood glucose peak response, or a number of other behaviors and physiological parameters.

The only measurable change was that treated cribbers drank more water, treated weavers drank less, and control horses show no change in water consumption.