Getting a Little Air

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As we know, oxygen is essential for the normal function of living tissue, for helping injured tissues heal, and for maintaining a healthy immune system, whether horse or human. But, kicking it up a notch, high pressure oxygen chambers, similar to those used in human medicine, facilitate faster healing for injuries and certain disease conditions in horses, too.

How Does It Work?

At normal atmospheric pressure, there is limited oxygen in blood plasma. Oxygen delivery to body tissues is accomplished when it binds with the hemoglobin in red blood cells; the red cells transport oxygen from the lungs and release it where needed in the body. Thus, oxygen delivery is limited to the hemoglobin saturation in the blood stream. If there is blood loss or impaired circulation due to injury, oxygen availability to body tissues is greatly reduced.

Here is where the increased pressure levels in a hyperbaric chamber come in. After the patient enters the chamber, air pressure is gradually increased, and when it reaches the prescribed pressure, the air is replaced with pure oxygen. As the patient breathes pressurized oxygen, it becomes dissolved in the blood and body fluids at high levels, making its way to any damaged area of the body that can’t be reached by normal circulation, such as vessels that have been damaged by injury or infection. In doing so, it promotes healing by helping preserve damaged tissue that would otherwise die from oxygen deprivation, and it also hastens elimination of toxic substances. Oxygen forced into areas of poor circulation, such as infected bone tissue, for instance, can help treat infections that don’t respond to ordinary treatment.

In human medicine, hyperbaric oxygen therapy (HBOT) is used to speed the healing of soft tissue injuries and aid recovery of stroke victims and burn patients. It is also used for treating multiple sclerosis, cerebral palsy, carbon monoxide poisoning, Lyme disease, coma, circulatory problems, severe wounds, diabetes and traumatic brain injuries.

The technology is not new. As early as the 17th century, one innovative physician named Henshaw was treating his patients in a crude airtight enclosure with pressurized air, pumping it in with a hand bellows. But the exaggerated claims for cure-all healing powers gave it the reputation of quackery. The only pressure chambers in common use during the 20th century (until the 1990s) were those designed for saving deep sea divers who came to the surface too quickly, suffering from the “bends.” In recent years, however, HBOT chambers for humans have become important in medicine and for treating sports injuries; some professional teams have chambers for their athletes.

HBOT for Horses

The first experimental chamber for horses was created in Vancouver, British Columbia by Tim Martin (Equinox Technologies) in 1999. His uncle had Thoroughbreds, and they decided to try hyperbarics on some of the horses’ injuries. They built a portable chamber that could be pulled around like a horse trailer, and tested it at racetracks. “We used our first unit to rehab Thoroughbreds at the track at Hastings Park in Vancouver, then took it to the track at Cloverdale, for trotters,” says Martin.

Dr. Doug Herthel purchased their first commercial unit for his Alamo Pintado Equine Medical Center in California. Herthel wanted one after losing a filly to a bone infection. He realized that oxygen therapy might have saved her. Herthel began treating a wide variety of equine ailments with HBOT and did a number of studies, such as inducing laminitis in test horses and reversing it with oxygen therapy. He found that that oxygen therapy works very well for treatment of laminitis in the early stages; it’s harder to reverse the condition if there is already severe damage and the coffin bone has dropped. In acute laminitis, however, the horses’ pain was greatly reduced after just one treatment, due to improvement in impaired blood circulation.

Herthel found that many surgical colic cases responded better to surgery when treated with HBOT before and after surgery, and that chronic wounds were able to heal. One of his early cases was a severe tendon sheath infection on a horse’s leg that was so terrible the horse was to be put down. After three treatments with HBOT and surgical flushing, the wound healed and the horse became sound.

Some of the first injuries treated with HBOT were bowed tendons. “We’ve had great success, with some horses back in racing again in four weeks,” says Martin. His company now makes five different horse chambers, including a single and a double unit (which can treat two horses at once), portable and stationary, and also a vertical 10-foot diameter two-horse chamber in which a horse can be turned loose, as in a stall. “We also sell smaller chambers for small animal treatment,” he says.

One of their first small chambers was used for treating foals at Hagyard, Davidson and McGee (now called Hagyard Equine Medical Institute) in Lexington, Ky. It was instrumental in saving many septic foals that suffered from severe joint infection, and foals with pneumonia. Hagyard now has a larger chamber, enabling it to treat adult horses as well as foals.

As explained by Dr. Nathan Slovis at Hagyard, some types of bacteria are very susceptible to high concentrations of oxygen. “The high pressure oxygen also helps increase white blood cell function. High oxygen levels can penetrate deep into bones, where infections may lurk. We leave a sick foal in the chamber for 20 minutes to an hour, once a day, for several days,” says Slovis. Their chamber has also helped save a number of “dummy” foals that suffered from birth asphyxia (going without oxygen too long during birth).

A study at Hagyard shortly after it got its first chamber consisted of treating all foals that did not respond to standard treatments for septic joints (systemic antibiotics, flushing the joints, etc.). A high percentage of these foals are put down, and the ones that survive are often crippled. To improve the odds, veterinarians at Hagyard used HBOT on all the hopeless foals (the ones that were going to be put down after 30 to 90 days of traditional treatment), combining HBOT with continued antibiotics. They had a 60 percent success rate (recovering to soundness). They also found that if sick foals can be started on oxygen therapy early on, the recovery rate is even higher.

The first breeding farm to install a chamber was Winstar Farms, in Kentucky. Bill Casner wanted to be able to treat horses on the farm, including newborn foals that suffer from oxygen shortage, or foals that develop septicemia and joint infection. “If we combine HBOT with the other protocols as soon as the foal gets sick, in two weeks the foal is fully recovered.

“One reason it works so well in infections is that it increases blood flow to the site, along with antibiotic delivery,” explains Casner. “In addition, the oxygen therapy increases effectiveness of the antibiotic and magnifies the way it works against bacteria. Oxygen acts to kill most bacteria, because the types that cause serious infection are usually anaerobic, working best in an environment without oxygen. At pressure (higher levels of oxygen), it also is detrimental to aerobic bacteria. HBOT also stimulates faster cell turnover, so it stimulates healing,” he says.

HBOT at U. of Tennessee

A growing number of veterinary hospitals and rehabilitation centers are now using hyperbaric chambers for treating horses. There is a chamber at the College of Veterinary Medicine, University of Tennessee, for example. Clinicians there have used this technology for five years. Dennis Geiser, DVM, assistant dean of Organizational Development at the University, says, “Hyperbarics for horses is still relatively new. Most of the information we have on horses (for what we treat and how we treat it) is still mostly anecdotal, based on cases that come in. There is very little controlled research that has been reported in veterinary literature,” he says.

But, Geiser adds, “We’re excited about doing research; one of our residents completed a project last year on wound and graft healing and reported at the American College of Veterinary Surgeon’s meeting in Chicago. This is one controlled study we’ve done.

“Our Veterinary Hyperbaric Medicine Society (VHMS), which was started two years ago, is a case-based registry. There are several facilities around the country that are members, including one in Redmond, Wash., and they send us the cases they’ve done, how they’ve done them, and what the results were. We are putting these in a spreadsheet and collating the information, to see what kinds of similar cases have been done and what the results were. Our plan is to meet periodically and discuss what we are doing,” says Geiser. “This will be a way to compare notes to see what works best and how to improve various techniques.

“We are trying to develop a certification program for veterinarians and veterinary technicians, so a person can become a certified veterinary hyperbaric medicine technician. We’re also developing a task force to look at safety issues, because these chambers are a little different than the human chambers in terms of fire risk. We have a website for the VHMS, so it’s slowly taking shape,” he says.

“We are trying to get information out to veterinarians as quickly as we can,” Geiser continues. “It takes a while to get things going with research and get projects funded. There is still a lot of skepticism among veterinarians. I think many of them look at it like they look at acupuncture and other alternative medicines.

“Right now its use is mainly client driven. If one client has a horse that’s treated and does well and tells another person, more clients want it. Eventually, this will be veterinary driven; veterinarians will be referring horses to centers because they know it works,” says Geiser.

Treatable Ailments

So where have they found success? “We treat wounds, and have also found HBOT beneficial in horses with endotoxemia and those with osteomyelitis. We treat athletic injuries like tendon and ligament tears that don’t heal well. The horse’s lower leg is a good test case for hyperbaric treatments, since it has poor blood flow and poor tissue perfusion. If we can increase the oxygen in the blood flow that it has, this is very beneficial.

“I’ve seen cases of OCD and bone cysts that have been treated and they show good improvement. Any tissue that is diseased or damaged can be helped in healing, so we are hoping to be able to show that HBOT decreases length of hospital stay. It’s helpful in treating post-operative colics. Colon torsions produce a lot of edema in the intestine, and it’s very beneficial in those. If a horse needs a portion of dead intestine taken out it is also very helpful.” The extra oxygen helps minimize reperfusion injuries (when blood goes back into the compromised tissues after the surgery) and improves gut motility. It speeds healing so the horse doesn’t have to spend so much time in the clinic.

How Much?

Unfortunately, none of this comes cheap. “Cost per treatment runs about $325 to $1,000, depending on the facility,” says Geiser. That’s because an equine chamber costs between $450,000 and $500,000. And that’s just the beginning, he adds. “You also need an oxygen source. In the end, you have to treat a lot of animals to make it pay for itself,” he says.

A large liquid oxygen tank requires an installation fee and a monthly rent on the tank, which is about $600 per month. It takes $10 to $12 worth of oxygen to fill the equine chamber each time. Then, “We have to charge for our technician’s time to run the chamber. It takes an hour and a half to get a horse prepped, run him through a cycle, and get him back out again,” he concludes.

But consider the alternative. When all is said and done, Geiser feels hyperbarics will be of benefit to a lot of animals that otherwise would be put down.