No abstract

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.

No abstract

Wildlife researchers need to understand the effects of biotelemetry tags in order to better weigh benefits versus risks. We describe tag-site healing and pathology of three beluga whales, Delphinapterus leucas, found dead in Alaska. The tags were secured with two or three nylon rods that pierced the dorsal ridge, and one beluga also had a LIMPET tag. The tag wounds in one Cook Inlet beluga featured a normal healing response with minimal inflammation $12 years posttagging. Photo-ID studies of another Cook Inlet beluga demonstrated degeneration of the tag wounds over several years. It died $12.8 years posttagging of bronchopneumonia and septicemia due to Staphylococcus aureus that also infected the tag wound. A Bristol Bay beluga died 4 months posttagging. Although it may have been predated by a killer whale attack, Orcinus orca, the tag site was inflamed and infected with Streptococcus uberis which spread to an abscessed lymph node. To reduce the risk of infection, researchers should adopt strict sterilization protocols for all implanted parts of tags and continue research into improved tagging methods. Clinical and behavioral assessment

We describe a research MRI protocol for ​in vivo​ evaluation of pinniped brains using standard human clinical MRI hardware and pulse sequences. Our intended application is to study development of California sea lions (​Zalophus californianus​) exposed ​in utero​ to domoic acid (DOM) produced by harmful algae blooms in the coastal Pacific Ocean. In cases where the fetus survives to birth, exposure to the toxin ​in utero​ could result in developmental abnormalities leading to neurological and behavioral deficits. Prior studies on sea lions naturally exposed to DOM as adults have demonstrated hippocampal atrophy and altered mesial temporal connectivity. This MRI protocol is therefore intended to depict the hippocampal formation as the primary region of interest, and to provide longitudinal measures of brain functional and structural connectivity as well as quantitative anatomical evaluations. Scan quality and utility are assessed by comparison with prior studies in live and post mortem sea lion brains. We include the first determination of cerebral blood flow mapping using MRI, and also the first fiber tractography using diffusion-weighted imaging from a live sea lion brain. The protocol also facilitates screening for common neurological pathologies, including tumors, trauma and hemorrhages. We believe the protocol would be suitable for any pinniped that can fit inside a human MRI scanner.

Plasma clearance of iohexol was evaluated in eight anesthetized California sea lions (Zalophus californianus), without evidence of renal dysfunction, to determine if the one-compartment model and the sample protocol used in dogs and cats could be applied to this species. Nonlinearity between samples in 75% (6/8) of sea lions voided those results. An additional two anesthetized sea lions were sampled at 5, 30, 45, 60, 120, 180, 240, and 360 min post iohexol injection and semi-logarithmic curves calculated. Plasma iohexol clearance values calculated by one-, two-, and noncompartment models were in poor agreement, suggesting that the standardized protocol described for dogs and cats cannot simply be applied to California sea lions, probably due to the effects of the dive reflex induced during anesthesia.