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We measured respiratory flow (V̇), breathing frequency ( f R ), tidal volume (V T ), breath duration and end-expired O 2 content in bottlenose dolphins (Tursiops truncatus) before and after static surface breathholds ranging from 34 to 292 s. There was considerable variation in the end-expired O 2 , V T and f R following a breath-hold. The analysis suggests that the dolphins attempt to minimize recovery following a dive by altering V T and f R to rapidly replenish the O 2 stores. For the first breath following a surface breath-hold, the end-expired O 2 decreased with dive duration, while V T and f R increased. Throughout the recovery period, end-expired O 2 increased while the respiratory effort (V T , f R ) decreased. We propose that the dolphins alter respiratory effort following a breath-hold according to the reduction in end-expired O 2 levels, allowing almost complete recovery after 1.2 min.

Recent dogma suggested that marine mammals are not at risk of decompression sickness due to a number of evolutionary adaptations. Several proposed adaptations exist. Lung compression and alveolar collapse that terminate gas-exchange before a depth is reached where supersaturation is significant and bradycardia with peripheral vasoconstriction affecting the distribution, and dynamics of blood and tissue nitrogen levels. Published accounts of gas and fat emboli and dysbaric osteonecrosis in marine mammals and theoretical modeling have challenged this view-point, suggesting that decompression-like symptoms may occur under certain circumstances, contrary to common belief. Diagnostic imaging modalities are invaluable tools for the non-invasive examination of animals for evidence of gas and have been used to demonstrate the presence of incidental decompression-related renal gas accumulations in some stranded cetaceans. Diagnostic imaging has also contributed to the recognition of clinically significant gas accumulations in live and dead cetaceans and pinnipeds. Understanding the appropriate application and limitations of the available imaging modalities is important for accurate interpretation of results. The presence of gas may be asymptomatic and must be interpreted cautiously alongside all other available data including clinical examination, clinical laboratory testing, gas analysis, necropsy examination, and histology results.

A five-year-old red kangaroo (Macropus rufus) presented with bilateral, firm thickening of the radius, ulna and metatarsal bones with local tissue hyperthermia. Radiographs revealed a soft tissue opacity left intrathoracic mass lying cranial to the heart, and extensive areas of smooth to palisading periosteal reaction along radius, ulna and metatarsus bilaterally. Culture of an aspirate from the mass yielded Actinomyces species. Treatment consisting of injectable penicillin and oral amoxicillin/clavulanic acid, meloxicam and tramadol was implemented for nine months. While receiving antibiotic therapy, the animal’s clinical condition improved, however, clinical signs returned after antibiotics were discontinued. Keeping it on daily medications indefinitely was considered neither practical nor safe for the staff and highly stressful for the animal. The kangaroo was euthanased one year and two months after initial diagnosis. Gross necropsy and histological findings confirmed the clinical diagnosis of pulmonary actinomycotic abscessation with hypertrophic osteopathy.

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