The influences of hyperbaric oxygen therapy with a lower pressure and oxygen concentration than previous methods on physiological mechanisms in dogs

Abstract

Recently, hyperbaric oxygen therapy with a lower pressure and oxygen concentration (L-HBOT) than previous methods has been used for dogs in Japan; however, the influences of L-HBOT on dogs have not been clarified. To verify the influences of L-HBOT on physiological mechanism in dogs, we investigated blood gas parameters, glutathione peroxidase (GPx) activity, heart rate variability, stress-related hormones and skin conductance (SC) in 4 clinically normal beagle dogs with catheters in their carotid arteries and jugular veins when they were quiet, after running, after receiving L-HBOT (30% oxygen concentration, 1.3 atmospheres absolute, 30 min) or after not receiving L-HBOT. The results showed there were no changes in blood gas parameters, heart rate variability and catecholamine levels after L-HBOT. GPx activity was significantly higher, and the SC and cortisol level were lower in dogs that received L-HBOT than those when they were quiet. These results suggested that L-HBOT may have a small influence on oxygenation dynamics, activate antioxidant enzymes such as GPx, restrain autonomic nervous activity and control the balance between oxidation and antioxidation inside the body.

Fig. 1.

Study protocol. Seven days after catheter placement, we studied the 4 dogs in a crossover trial (1) when the dogs were quiet, (2) after running, (3) after non L-HBOT and (4) after L-HBOT. Briefly, a dog underwent one study protocol and then underwent the other 7 days later.

Fig. 2.

GPx activity for the 4 treatments. GPx activity in erythrocytes of the 4 dogs when they were quiet, after running, after non L-HBOT and after L-HBOT. The bars indicate mean values, and the lines indicate the SD. **Significant difference vs quiet (P<0.01).

Fig. 3.

Power spectral analysis of heart rate variability for the 4 treatments. Power spectral analysis of heart rate variability of the 4 dogs when they were quiet, after running, after non L-HBOT and after L-HBOT. (a) LF/HF value. (b) RRI. The bars indicate mean values, and the lines indicate the SD.

Fig. 4.

Stress-related hormone levels for the 4 treatments. Stress-related hormone levels in blood of the 4 dogs when they were quiet, after running, after non L-HBOT and after L-HBOT. (a) Cortisol levels. (b) Adrenaline levels. (c) Noradrenaline levels. The bars indicate mean values, and the lines indicate the SD. *Significant difference vs quiet (P<0.05).

Fig. 5.

SC for the 4 treatments. SC of the 4 dogs when they were quiet, after running, after non L-HBOT and after L-HBOT. The bars indicate mean values, and the lines indicate the SD. **Significant difference vs quiet (P<0.01).