Gas Bubble Trauma in the Bullfrog Rana catesbeiana

Adult bullfrogs, Rana catesbeiana , were exposed to water supersaturated with atmospheric air. Exposure to a differential pressure (δP) of 250 mm Hg [total gas pressure (TGP) = 132.9% of atmospheric pressure] resulted in a 40% mortality within one day owing to the accumulation of gas in the vascular system. Exposure to a AP of 128 mm Hg (TGP = 116.8%) for four days had no effect on bullfrog mortality, but produced subcutaneous gas bubbles in the webbing and on body surfaces, followed by hyperemia (tissue engorged with blood through blood vessel dilation), and petechial (small subcutaneous hemorrhage spot) and ecchymotic (large subcutaneous hemorrhage spot) hemorrhaging. Owing to accumulation of gas under the skin, these frogs typically floated and were unable to remain submerged. These clinical signs are similar to those commonly reported for “redleg” disease syndrome in bullfrogs. When held at a δP of 67 mm Hg (TGP = 108.8%) for 27 days, no clinical signs of gas bubble trauma were observed.