Common Uses and Adverse Effects of Hyperbaric Oxygen Therapy in a Cohort of Small Animal Patients: A Retrospective Analysis of 2,792 Treatment Sessions

Hyperbaric oxygen therapy (HBOT) is commonly utilized for various human conditions<br>with a low incidence of major adverse effects (0.002–0.035%). Despite growing use in<br>veterinary patients, there remains a paucity of literature describing its use and associated<br>complications. The purpose of this study was to report clinical use of HBOT in small<br>animals and identify the rate of major adverse events at a university teaching hospital.<br>Electronic medical records were searched for small animals receiving HBOT between<br>November 2012 and February 2020. Data extracted from the medical records included<br>signalment, treatment indication, and adverse events. Treatment sessions totaled 2,792<br>in 542 dogs, 24 cats, and 10 pocket pets and exotics. Common indications included<br>neurologic injuries (50.4%), tissue healing (31.4%), control of oomycete infection (5.5%),<br>neoplasia or post-radiation injury (5.4%), and various miscellaneous conditions (7.4%).<br>Observed minor adverse events included agitation in two dogs and vomiting in three<br>dogs. The most common major adverse event was central nervous system (CNS)<br>oxygen toxicity in 19 dogs. Central nervous system oxygen toxicity, manifesting as focal<br>or generalized seizures, occurred in 0.7% of treatment sessions, with increasing age<br>(p = 0.01) and female sex (p = 0.01) identified as risk factors. One dog developed<br>pulmonary edema following HBOT which is a reported adverse event in humans or may<br>have been a manifestation of progression of the dog’s underlying disease. No adverse<br>events were noted in cats or other species. In conclusion, HBOT appeared safe across<br>various indications, although oxygen toxicity affecting the CNS was higher than reports<br>in humans. Future prospective, randomized, controlled trials should evaluate specific<br>clinical indications and outcomes.<br>