For both humans and equines, exposure to high altitude not only affects athletic performance, but can also be life threatening, triggering high altitude cerebral or pulmonary edema. While there are numerous studies on the physiological adaptations of humans to altitude, there is little or no data on equines.

Equine research technician Holly Greene sayas that the altitude study could have an impact on the state's 240,000 equines.

A Cal Poly Pomona research team hopes to change all that through a study educating horse owners and the scientific community on the dangers of moving equines from low to high altitudes without taking appropriate precautions. The team has performed exhaustive tests on 12 horses and mules in the High Sierras.

"With more than 240,000 equines in California, a state that has easy access to both high and low altitudes, such a study could have a huge impact, especially on those who routinely trailer their equines to the mountains for trail riding, athletic events or packing expeditions," says alumna Holly Greene, an equine research technician at Cal Poly Pomona.

A pilot study in 1996 featured a team from the university's Equine Research Center taking six horses to the University of California's White Mountain Research Station near Bishop to monitor their reaction to altitude changes.

The team discovered that horses, like humans, experience an immediate and dangerous 60 percent increase in pulmonary artery pressure at altitude, a fact that many horse owners were simply unaware of.

"When we analyzed the pilot study data, we decided it would be beneficial to look at other species within the equine world, especially those commonly used in the commercial packing industry," says Greene. "We tested burros in 2000 with very interesting results and decided to expand the study to include mules, a sterile hybrid cross between burros and horses."

Burros did not experience severe hypertension at altitude, although they did demonstrate some increase in pulmonary artery pressure. Mules, which are horse-like in shape and size yet incorporate the ruggedness and strength of burros in their genetic makeup, experienced more hypertension than burros but less than horses.

The findings will do much to aid in the development of practical guidelines for transporting horses, mules and burros safely into hypoxic environments. In addition, findings support new ways to care for equines commonly used at high altitude for work and recreation.

Cal Poly Pomona's study was funded by grants from the UC Davis Center for Equine Health, the American Mule and Donkey Society and the Agriculture Research Initiative, which is a $4 million award from the state to the four CSU colleges of agriculture-including Cal Poly Pomona's-to stimulate research in agricultural areas.

For more information on the Equine Research Center, call (909) 869-2156.