Cetacea

This chapter presents the pathology of cetaceans, a diverse group of mammals restricted exclusively to aquatic habitats. The taxa include the largest mammals on earth, the baleen whales (mysticetes), as well as marine and freshwater-toothed whales, dolphins, and porpoises (odontocetes). The pathologies of these species include infectious and non-infectious processes. With free-ranging cetaceans, trauma associated with anthropogenic activities (entanglements, vessel or propeller strikes, blast injuries) are among the most significant contributors to morbidity and mortality. Interspecific or conspecific interactions such as infanticide, predation, or aggression have also been documented. In animals under managed care, concerns include nutritional, degenerative, geriatric, and metabolic processes, such as the formation of ammonium urate renal calculi. Viral pathogens reported to have individual and population-level effects include morbilliviruses, pox virus, and herpes viruses. Bacteria, protozoa, and metazoan parasites may cycle exclusively in the marine environment or represent land-to-sea flow (pollutagens). Both free-ranging and captive animals have important neoplasms, including tumors in beluga whales from the St. Lawrence Estuary and oral squamous cell carcinomas in bottlenose dolphins in managed care.