Courtesy of Kentucky Equine Research
Hyperbaric oxygen therapy, or HBOT, refers to a treatment in which a patient is placed in a sealed chamber and exposed to oxygen at several times normal atmospheric pressure. Oxygen is forced into the blood and other body fluids (lymph, cerebrospinal fluid, bone marrow), destroying bacteria and helping to heal injuries.
How does HBOT work?
The air we breathe contains about 21% oxygen, with the remainder made up of nitrogen and tiny amounts of other gases. Red blood cells take up oxygen from the lungs, carrying it in dissolved form to all parts of the body. Breathing more rapidly or deeply does not increase the amount of oxygen carried by the blood, and breathing pure oxygen at normal atmospheric pressure increases it only slightly.
However, putting a horse in a hyperbaric chamber and increasing the atmospheric pressure to much greater than normal is very effective in enhancing the oxygen-carrying ability of the blood because oxygen is forced into the plasma in addition to being carried by the red blood cells.
HBOT aids healing in the following ways:
- Increasing oxygen to the body stimulates growth of new blood vessels in bone or soft tissue, thus allowing more oxygen-rich blood to reach the affected area after treatment.
- Swelling and inflammation are decreased, allowing blood (and therefore oxygen) to flow more freely to the area.
- High oxygen levels increase the ability of the white blood cells to kill bacteria in infected tissues.
- Anaerobic bacteria are killed directly by the high level of oxygen reaching infected tissues, even if normal circulation has been affected.
What types of injuries and ailments can be treated?
When used as an adjunct to traditional veterinary techniques, HBOT has produced excellent results in a variety of applications.
- HBOT helps the uterus return to normal size and shape following foaling, and dummy foals improve with increased blood flow to the brain. The therapy has also been reported to increase libido in aging stallions.
- Anemia or blood loss. For horses that are anemic and those that have lost a large volume of blood because of injury or surgery, HBOT allows the remaining blood to carry a larger amount of oxygen, sustaining body functions while more blood is being produced.
- Bone infection. HBOT increases the oxygen concentration in all body tissues including bone and bone marrow. Bone infections that have not responded to traditional antibiotic therapy often clear up after treatment in the hyperbaric chamber. Joint infections in foals also respond well to this therapy.
- Wounds in skin and muscle tissue. Improved oxygen delivery and stimulation of capillary formation assist in healing, especially in skin grafts, amputations, ulcerated wounds, and injuries where tissues have been crushed and circulation has been destroyed or impaired.
- By enhancing oxygen delivery and minimizing inflammation and swelling, HBOT can dramatically minimize the destruction of tissue structures within the hoof.
- Post-surgical patients. Horses recovering from colic surgery and other procedures benefit from HBOT to oxygenate damaged tissues, restore blood flow, and reduce swelling.
- Connective tissue injuries. Torn ligament and bowed tendons heal more quickly when HBOT is included in treatment.
How do horses respond to being treated?
Protocol is different for each horse, and many conditions are treated with HBOT sessions of 30 to 90 minutes per day over a period of several days or weeks. Operators monitor their equine patients with audio and video equipment. Most horses show no reluctance to enter or remain in the chamber, with some even going to sleep during treatment. Human patients report a feeling of mild elation and wellbeing after HBOT, and there is no reason to think that horses respond any differently to the experience.
Where is this technology available?
Pressure chambers designed to treat horses are large, heavy, and extremely expensive to produce, so they are not yet widely available. Central Kentucky has the largest concentration, with several veterinary clinics, rehabilitation facilities, and breeding farms using the therapy on a regular basis. Chambers with space for one to three horses are in operation at various locations in California, Colorado, Tennessee, and Texas. The design is constantly being updated, and the newest models resemble circular stalls with enough room for a horse to walk around and even lie down during treatment. Smaller chambers can be moved from place to place, offering on-farm treatment to horses that can’t easily be moved.
What research has been done regarding HBOT?
Practitioners and horses owners are quick to sing the praises of this therapy, and very few negative results have been reported. However, while use is increasing, relatively few controlled equine experiments have been performed. The therapy has been used on human patients for a number of years, and this has been the basis for establishing basic guidelines for use with horses. A 2002 University of Kentucky study using HBOT to treat advanced septic osteomyelitis in foals concluded that the therapy was successful in reducing swelling and lameness. The report emphasized a key point: by itself, HBOT is not a magic remedy for any and all conditions. Traditional treatments for illness or injury should be pursued, with HBOT used as an additional tool to promote healing.