The condition of Debbie Stephens’ grand prix jumper All Star was deteriorating rapidly in February of 2009. After a routine rhinopneumonitis vaccination, he showed severe neurological symptoms as a result of a virulent bacterial infection in his spinal cord.

“When it went downhill, it went downhill fast. He couldn’t move or eat or turn his head or lay down,” Stephens said.

“He’d had his sacrum injected maybe a month before the immunization, and it’s hard to say, but we’re thinking possibly that went septic,” she added, “and when we gave him the rhino shot, possibly his immune system was so compromised that he contracted the infection.”

Stephens’ veterinarian, Dr. Haynes Stevens, was aggressively treating All Star with antibiotics and anti-inflammatories, but without good results.

“This horse had atrophied so badly that there was an L shape from his spine to his hip bone. He was concave where his gluteal muscles are. I’ve never seen anything like it before,” said Stephens, of Palmetto, Fla. “But I just wanted to save him no matter what, even if he just lived in a field for the rest of his life.”

Stevens recommended consulting with Dr. Meg Miller-Turpin of the Equine Hyperbaric Center of South Florida.

“In a spinal tap, we got pus from his cerebrospinal spinal fluid, and that is horrible,” Miller-Turpin said. “He’d lost all the muscle on one side, and he couldn’t urinate. He’d lay down and then have difficulty standing back up.”

All Star received 30 sessions of hyperbaric oxygen treatment, conjunctively with 60 days of antibiotic treatment.

“I told Debbie that they don’t usually recover from these types of infections, but he made a total recovery,” said Miller-Turpin. “Even with the hyperbarics, I told her his prognosis was very guarded. It was guarded even for his survival, but he would most likely retain permanent neurological deficits and not be usable as an athlete. I didn’t think the horse was going to make it, and he really made a remarkable recovery.”

Within months, All Star had recovered enough to go back to work.

“We put weighted boots on him, and we’d just walk him, and then he trotted with them. We worked the weights up just like you would in a rehab center. When he started jumping, we just jumped a lot of low jumps to get his muscles back,” said Stephens.

All Star was back to jumping in small classes by August, then showed in the adult amateur division in early 2010 with Kyle Owens.

By the spring of 2010, All Star was strong enough to show in the high junior jumper classes with Michael Murphy, and he traveled to Europe that summer as Murphy’s second mount on the U.S. Equestrian Federation Young Riders tour, showing in France, Belgium and the Netherlands. In the fall, Stephens took back the reins on All Star for grand prix classes, and they placed sixth in the $250,000 FTI Consulting Grand Prix CSI-W at the Hampton Classic (N.Y.) in September.

“It’s a real fairytale,” said Stephens. “I’m thrilled that he lived and even more thrilled that he’s back jumping. The hyperbaric chamber was a team effort, and I have to say that was a key factor in his recovery. He could have gone either way, and without it, I think he wouldn’t have lived. He was a really sick horse. He was on IV antibiotics and all kinds of treatment, but what I think really turned him around was the hyperbaric oxygen. He was in such incredible pain when he’d go into the chamber, and then when he came out, he got relief. For about an hour, you could see he was feeling better. He kept getting better and better. Every time he went to the chamber, his period of being in less pain lasted longer and longer. And his blood count got better, and he got stronger,” Stephens continued.

“The hyperbaric chamber wasn’t the only thing, but it certainly was a huge contributing factor that put him over the edge to live,” she said. “It’s an amazing thing.”

Getting Oxygen On The Fast Track

What is this fairytale cure? It’s not a new drug or a high-tech process. It’s simply oxygen, delivered to the body in a pressurized form known as hyperbaric oxygen therapy.

In hyperbaric oxygen therapy (HBOT), the horse is contained in a sealed chamber. Then ambient air is removed through the top of the chamber, while pressurized 100 percent oxygen is released into the chamber. The oxygen is inhaled by the horse and absorbed into the blood.

The normal sea level atmospheric pressure of air is 14.7 pounds per square inch. The pressure in a hyperbaric chamber is measured by atmospheres absolute, and 14.7 PSI is equivalent to 1 atmosphere, or ATA. So horses live at 1 ATA, or normal atmospheric pressure. In the hyperbaric chamber, air is pressurized to higher ATAs. At 2 ATA, the pressure in the chamber is the equivalent of being 33 feet under water, or 29.4 PSI, and at 3 ATA, the pressure is at 44.1 PSI. Hyperbaric oxygen therapy utilizes between 1.5 ATA and 3 ATA, though most conditions are treated at 2 or 2.5 ATA.

Breathing ambient air at sea level pressure results in about 0.31 milliliters of dissolved oxygen per deciliter of blood. Breathing 100 percent oxygen at sea level pressure results in about 2.1 ml of dissolved oxygen per dl of blood. Breathing 100 percent oxygen at 2 atmospheres of pressurization results in 4.4 ml of dissolved oxygen per dl of blood; at 3 atmospheres, that number goes up to 6.8 ml.

Oxygen, carried in the blood stream by plasma and red blood cells, is a potent healing agent for tissues in the body. But the body can only absorb so much oxygen into the blood via respiration of normal ambient air, even if it’s 100 percent oxygen. When the horse inhales 100 percent oxygen in a pressurized form, however, the amount of oxygen absorbed into the plasma is increased exponentially.

With more oxygen dissolved in the blood plasma, more oxygen can get to body tissues to aid the healing process. It’s similar to pressure-washing an internal site in the horse’s body with oxygen.

While HBOT can work wonders, it’s strictly an adjunct, or additional, therapy. It doesn’t take the place of conventional treatments.

“It should be considered and the options should be weighed,” said Dr. Nathan Slovis, a board-certified internist and hyperbaric technologist at Hagyard Equine Medical Institute in Lexington, Ky. “It’s a decision made case by case and depending on the injury and the budget. I use conventional treatment, and if that’s not working after X amount of time, I’ll bring up hyperbarics.”

Oxygen Heals

The applications for HBOT are many, but they all involve increasing the amount of oxygen that gets to the site of injury or infection.

Let’s say your horse gets cast in his field, getting his leg caught in the fence. The leg swells from bruising.

“Not only do you have the initial injury of deep tissue bruising, but you also have edema,” said Slovis. “Edema decreases blood flow to certain areas of that leg. If a horse gets a severe injury to the leg and it develops severe edema, those deeper tissues in the leg—tendons, ligaments, muscle—will weaken and even die if they don’t get oxygen. If tissue dies, then it’s going to remodel and form scar tissue. Or it may never heal properly again. “Oxygen cannot diffuse properly through an edemitive leg to areas that have been traumatized,” Slovis continued.

“Hyperbaric therapy pressurizes oxygen in the blood so it can diffuse more effectively across the edemitive tissue to parts of the body that need oxygen to survive and heal, the deep tissue structures.

“I know it doesn’t seem like much, but oxygen normally will diffuse into tissue to the depth of about a thickness of a piece of paper. With hyperbarics, it can diffuse across, depending on the pressures, up to three thicknesses of paper. You and I think, ‘Three sheets of paper, that’s nothing. Big deal.’ But you have so many capillaries; if you can pressurize oxygen into those capillaries, three thicknesses of paper can be life or death for tissue,” said Slovis.

Pressurized oxygen in the plasma also reduces the amount of pressure in the blood vessels and capillaries, also known as vasoconstriction, which aids in reducing swelling. HBOT can also increase oxygen delivery to areas with compromised capillary circulation due to clotting in the blood vessels.

HBOT also acts to release vascular growth factors, which results in the growth of more capillaries, further deepening the delivery of oxygen to tissues. HBOT has also been shown to speed the healing of large surface wounds, encouraging skin growth by stimulating fibroblasts, which build new tissues.

Battling Infection

Hyperbaric oxygen therapy has shown remarkable results in treating infections, especially bone infections and abdominal or lung abscesses that are difficult to treat with conventional antibiotics.

Delivering more oxygen to an infection site not only helps with reducing edema, it also speeds resolution of the infection, jump-starting the work of the antibiotics.

“Bacteria hate oxygen. With oxygen, you create free radicals. Cells in our body have natural antioxidants that can absorb free radicals. Bacteria don’t. If you get all these free radicals in there, you’ll disrupt the bacteria and weaken them, so that the antibiotic can work better,” said Slovis.

In All Star’s case, hyperbaric oxygen therapy helped reduce the inflammation around the spinal cord, enhancing circulation. The increased oxygen delivery to the site also helped increase the effectiveness of the antibiotics.  “I can’t say for sure if it wouldn’t have gotten better without the hyperbaric treatment, with just antibiotics and anti-inflammatories and putting him in the sling, but the majority of those kinds of cases don’t recover the way he did,” Miller-Turpin said.

Bone infections show significant progress with the addition of HBOT. Within the bone are cells called osteoclasts, which work to absorb dead and diseased bone so that new bone can grow.

“If osteoclasts can’t clean up dead bone, the bone will never heal properly and will always be brittle. Osteo-clasts need more oxygen than the bone-producing cells; without oxygen they’re not going to work properly,” said Slovis.

“If you have diseased bone, a large part of the blood supply has probably also been destroyed. But pressurized oxygen can get deep into that tissue. With oxygen diffused into that tissue, the osteoclasts can work and clear out the dead bone. Then the osteoblasts, which also need oxygen to work effectively, can form new bone.”

Giving New Life To Lungs

Miller-Turpin has seen good results with treating joint infections and tendon sheath infections with HBOT. “It seems the antibiotics work better. We’ve had a few horses go into the chamber three-legged lame, and when we take them out, they’re walking on the leg,” she said. “I think that relief is because the HBOT helps take away some of the swelling. It may come back in four hours, but if you can decrease the swelling for that amount of time and make the horse more comfortable, then you’re getting rid of inflammation.”

Infections and abscesses deep within the body, such as in the abdomen or lungs, respond well to HBOT.

“I’ve had good luck with treating pleuropneumonia with hyperbarics,” said Miller-Turpin. “If they have a lot of inflammatory fluid in their chest, then we still need to put chest tubes in to drain this fluid.  However, we also use the hyperbaric oxygen in conjunction with the intermittent chest tube drainage, and it seems to help them recover. We had two horses that had horrible infections and were definite candidates for a rib resection, where you remove a rib and drain the pleural space. But we didn’t do the resection—we treated them in the chamber, and now the horses are back into work.”

Miller-Turpin also treats a large number of racehorses with exercise-induced pulmonary hemorrhage, which can be caused by a persistent infection in the lungs. HBOT can help resolve the infection and heal lung tissue. Slovis has also seen the use of HBOT at the racetrack, as part of a post-race therapy.

“After a horse works hard in a big race, the horse goes into oxygen debt, because the body has been in anaerobic metabolism. Hyperbaric will repay that oxygen debt a little bit faster. It may reduce soreness the next day. People use it post-racing for a faster recovery and preventative measure,” he said.

But Slovis and Miller-Turpin emphasize that HBOT is not a performance-enhancing procedure and is not intended for use before a horse competes. In fact, some tracks and some state racing commissions have banned horses from running within a certain amount of time after HBOT treatment.

“If you have a healthy horse and you think you’ll put it in a chamber and hyper-oxygenate it, and it will go better, that’s not true,” Miller-Turpin said.

A Myriad Of Applications

Another useful application for HBOT is in recovery from colic surgery, especially for colon torsion. “When a bowel has been twisted and then untwisted, you get a ton of free radicals that are released and can injure the bowel further. Hyperbaric oxygen will relieve that and decrease them by altering the way the white blood cells react to the injured blood vessels in that bowel,” said Slovis.

HBOT can also increase blood flow to the intestinal tissues, aiding healing.

“We had a case last year where they resected the entire colon and then immediately after surgery put the horse in the chamber,” said Miller-Turpin. “It helped reduce the endotoxemia and inflammation in the intestines.”

Miller-Turpin’s partner at the Equine Hyperbaric Center of South Florida, Dr. Byron Reid, will sometimes put a horse in the hyperbaric chamber immediately after colic surgery.

HBOT also facilitates the healing of the incision site after colic surgery, reducing the incidence of hernias.

Veterinarians are applying the benefits of HBOT to many conditions. Early stage laminitis can respond well to HBOT, as the oxygen helps reduce inflammation and enhances circulation. Researchers at the University of Tennessee are studying the effects of HBOT on laminitis.

Head trauma and birth asphyxia are other problems that have responded well to HBOT, as well as infections from puncture wounds or spider bites. Horses with smoke inhalation benefit from the increased oxygen delivery of HBOT, while surface burns heal more quickly.

Veterinarians are also considering the possibility that HBOT could be beneficial in treating Lyme disease and Equine Protozoal Myeloencephalitis.

“There are a multitude of approved indications for hyperbaric oxygen,” said Slovis. “We’ve extrapolated a lot of information from human data, and now human medicine is looking at what we’re doing with hyperbarics. There are a lot of exciting things going on in hyperbaric therapy. The problem is getting funding for all the studies.”

This article appeared in the Feb. 21, 2011 issue of The Chronicle of the Horse. To subscribe and get access to all the Chronicle’s news and feature stories, click here.