Two landmark clinical studies examining the effects of treating foals with septic (infected) joints and "dummy foals" (those which suffered from lack of oxygen during delivery) in hyperbaric chambers have begun in Lexington, Ky. Hagyard-Davidson-McGee veterinary hospital has two of these devices that deliver 100% oxygen in a pressurized chamber to sick animals. A one-horse model (fits two foals) will be used to treat septic foals. A smaller, neonate model will be used to treat dummy foals.

"Dummy foal" before (above) and two weeks after hyperbaric oxygen therapy.

Photos Courtesy Fairfield T. Baid, DVM, DIPL. ACVIM, ACVP, ACVECC:

The clinic treated two foals during its public introduction of the procedure on April 11--one outpatient filly which has shown significant improvement after 20 treatments for a salmonella-infected joint, and one in-patient colt with three resistant E. coli-infected  joints.

Initially, the HDM veterinarians wanted to confirm that the therapy was safe for foals. Nathan Slovis, DVM, Dipl. ACVIM, of Hagyard-Davidson-McGee said, "Now that we know it's safe, we can begin administering treatments to foals that have undergone routine therapy such as joint flushes and antibiotics, but that aren't recovering satisfactorily."

History of the Hyperbaric Chamber

A manufacturer in Vancouver, BC, holds the patent to equine hyperbaric chambers, which hit the market in 2000. Each chamber looks like a capsule-shaped horse trailer. Within the chamber, pressure can go up to between two and three "atmospheres"--an atmospheric pressure roughly equivalent to the pressure experienced at 66 to 99 feet underwater.

The first hyperbaric tank for human patients was built in France in 1834. In humans, the hyperbaric chamber is used to assist in the healing of burn victims, gangrene, and chronic wounds. Also, when divers surface too quickly, the tremendous pressure forces oxygen into their bloodstream, causing decompression sickness, or "the bends." These cases are often placed in a hyperbaric chamber in order to allow the body to equilibrate safely with the above-seal-level atmosphere.

"The therapy is supposed to increase the level of oxygen in the bloodstream, and the level gets so high that it more easily diffuses into the tissues to aid in healing," said Slovis.

Another potential use of the chamber is that the pressurized oxygen might improve the way antibiotics are utilized in the horse. "If we can oxygenate the tissues, the potency of the drug may be enhanced," Slovis added. (Learn more about how hyperbaric oxygenation therapy works at

While studies have shown that the therapy is effective in stimulating healing in humans and in laboratory animals, few studies have been completed in horses. Clinical studies on healing of certain adult equine athletic injuries in California suggest that the therapy is valuable. There are several chambers in use in California, Texas, Florida, and Kentucky, at veterinary clinics, therapy centers, and private farms (for example, WinStar Farm in Kentucky).
Whereas a typical hyperbaric chamber treatment in humans might last for several hours, with up to 20 to 30 treatments, it is not realistic to have that many treatments for each equine patient. Neonates must be sedated with valium before treatments in the smaller hyperbaric chamber, because if they were to thrash around, they could injure themselves.

"Our current sedative protocol gives us about an hour to work with," said Fairfield Bain, DVM, Dipl. ACVIM, ACVP, ACVECC, of Hagyard-Davidson-McGee. Dummy foals are treated for 30 minutes to an hour, for one to three treatments. Foals with bone infections will have 15-20 treatments that last one to 1 1/2 hours each.

Initially, this service will be available on a selective, research-only basis, and Equine Hyperbaric Oxygen Therapy owner Hub Johnson is providing the chambers to Hagyard-Davidson-McGee during the study so that there will be some hard numbers associated with the treatment's effectiveness. After the study is complete and if the data shows a significant improvement in animals treated in the chamber, each treatment could cost between $400 and $500. The initial cost of the hyperbaric chamber is from $175,000 to $200,000.

Bain estimates that 80% of neonates admitted to the Neonatal Intensive Care Unit have some degree of birth asphyxia. "We tried to pick two problems that we feel comfortable monitoring," said Bain. "We're in the world's Thoroughbred nursery. We see over 400 neonates a year, and we'll get to see those numbers we're looking for."

"We have just begun to admit neonatal patients to the Brain asphyxia portion of the study. Our first patient is about 3 weeks of age and has been reported to be doing very well. Our hope is that this brief therapy will reduce brain swelling and improve brain function in those foals with significant birth asphyxia."

By the end of the summer, Bain and Slovis hope to have treated at least 20 septic foals and 20 dummy foals in the hyperbaric chamber. It will be a prospective study in that veterinarians will compare the outcome of foals treated with hyperbaric therapy to records of foals with nearly identical symptoms.

Intermittently, the veterinarians hope to be able to use the larger hyperbaric chamber to treat grown horses recovering from torsion colic surgery, and mares which have abnormal placentas.

"We're happy with what we've seen so far," said Slovis, "but it is still a bit too early to make any conclusions."

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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