It’s been a few years since I covered the subject of hyperbaric oxygen therapy (HBOT), a treatment that involves placing patients in a sealed chamber and raising the air pressure and oxygen levels above those in the normal atmosphere at sea level. Back in 2013, I summarized the available evidence and reached this conclusion:
HBOT is a biologically plausible therapy with substantial in vitro and animal model research to support possible benefits in a variety of conditions. There is, however, almost no clinical trial evidence to support its use in companion animal species. Justification of veterinary use of HBOT comes only from extrapolation from basic principles, pre-clinical research, anecdote, and extrapolation from research in humans, so this should be viewed as an unproven, experimental veterinary therapy.
There are a few indications for which the human clinical trial research provides at least a moderate degree of confidence that HBOT is effective. There are many others for which there is only limited and low-quality evidence and no clear conclusion can be drawn. Not all uses validated in humans are relevant to veterinary use, and most veterinary applications have not been directly studied in people. Overall, the evidence is strongest for adjunctive use of HBOT to facilitate healing of chronic wounds not resolving with standard therapies.
HBOT is generally quite safe, but there are both minor and serious potential adverse effects, and there is some risk associated with the use of the equipment.
I followed this article with a brief report of warnings from the FDA about unsupported and exaggerated claims for HBOT in humans and a report on a human study showing no benefits for treatment of concussion. Given that I last looked at the literature 5 years ago, I thought it worthwhile to check for any new evidence on this treatment in veterinary patients. Unfortunately, there hasn’t been very much research published since 2013.
A 2017 review by two authors supportive of HBOT concluded:
There is a paucity of data about use of HBOT in veterinary medicine, and no randomized, controlled clinical trials for any condition have been published… HBOT holds therapeutic promise in animals and deserves clinical and research attention. However, the therapy is not benign, and understanding the basics of HBOT and possible complications is critical. Because the clinical information, apart from expert opinion and research experiments with small numbers, remains minimal, research is essential to expand information about the physiology behind the modality, condition-specific treatment parameters, and appropriate and efficacious indications for use in veterinary patients.
Since then, there have been two published veterinary reports. One study evaluated the safety of HBOT by recording any adverse effects noticed during 230 treatments in 12 cats and 78 dogs. Though this was only an observational study of short-term treatment, and there were a few other limitations, no serious adverse effects were seen. Minor effects, suggesting some discomfort and possible inner ear problems, were seen in some patients at a modest rate. This certainly doesn’t rule out the possibility of any more serious harm, and cases of significant injury have been reported in humans. However, this study supports the general findings in the limited veterinary literature that adverse effects of HBOT seem uncommon and typically minor. The only known fatality reported in veterinary HBOT involved an explosion which killed both the patient and the operator at an equine therapy facility in 2012.
There has been one study of HBOT in dogs published since my last review:
Latimer CR, Lux CN, Roberts S. Effects of hyperbaric oxygen therapy on uncomplicated incisional and open wound healing in dogs. Vet Surg. 2018 Aug;47(6):827-836.
This was an experimental study, not a clinical study. Ten lab beagles were given surgical wounds, and then given the same wound care (suturing, bandaging, pain control, etc.) except that 5 were given a series of HBOT treatments as well. Blinded observers evaluated wound healing scores, and biopsies of the wounds were examined. No effect of HBOT was seen, and the wounds healed the same regardless of whether the dogs got HBOT or not.
There are a number of limitations to this study, including the small number of dogs and the use of lab dogs with artificial wounds rather than a real-world population of dogs with the kinds of wounds that would typically be treated with HBOT. Nevertheless, the study certainly suggests there is no dramatic benefit to HBOT in the healing of routine, uncomplicated wounds.
The literature since 2013 has not provided any reason to alter my original conclusions. While HBOT appears to have promise based on theoretical reasoning, lab animal studies, and some validated uses in humans, there is still no convincing evidence to support any claims of benefits to veterinary patients. While the risks appear to be minimal, there is only weak and unreliable evidence of any benefits. The use of a complex, expensive, and potentially harmful treatment in the absence of any strong evidence for benefits is not the best way to use limited resources in veterinary medicine or to provide the best care to patients. Advocates for HBOT, especially those selling it as part of their practice, ought to focus on supporting rigorous and objective clinical studies to identify what real benefits, if any, there are from this therapy.