![]() In humans, the early stages of water intoxication include confusion, disorientation and vomiting, with progressive exposure resulting in hyponatremia, seizures, coma, and death ( 15). In terrestrial mammals, freshwater intoxicosis can occur if large quantities of freshwater are consumed in a short period of time as seen in psychogenic polydipsia (described in canines, hoofstock, and humans), self-imposed overhydration in Army recruits following heat-related injuries, iatrogenic causes (as seen in fluid overloading with intravenous fluids in hospitalized animal and human patients) and child abuse ( 11– 16). Little is known about the effects of prolonged freshwater exposure in dolphins, including the length of exposure time necessary to cause negative health impacts and the ability of a dolphin to recover following prolonged low salinity exposure.Įxposure to excessive freshwater causes a range of pathologies in mammals. Prolonged exposure to freshwater or low salinity water (8 PSU and avoided waters of <5 PSU ( 10). This case provides a unique opportunity to follow the progression of prolonged freshwater exposure and recovery in a bottlenose dolphin and highlights that dolphins in nearshore habitats face a combination of persistent natural and human associated threats. Elevated barium (Ba) concentrations in tooth dentin corresponded to increased seasonal freshwater discharge patterns, confirming repeated annual exposure to low salinity conditions prior to death and indicating freshwater exposure may pose an ongoing threat to dolphins in the region. This supports the need for future research in cetaceans to establish a species-specific approach. ![]() ![]() Post-mortem analysis of vitreous humor (used as a proxy for serum analytes and to determine post-mortem interval) was challenging to interpret and has not been validated in dolphins. A full necropsy was conducted and there was complete resolution of the skin pallor and skin lesions and no evidence of chronic renal or central nervous system lesions. Twelve weeks following release, the dolphin was found dead as a result of a fisheries interaction (peracute underwater entrapment). ![]() A satellite-linked tag was attached to the dorsal fin to track the dolphin following its relocation to a nearby brackish water bay (Perdido Bay, AL), a known habitat for bottlenose dolphins. The dolphin was deemed healthy enough for immediate relocation and release. Renal function was not affected (normal creatinine and urea nitrogen) and all other bloodwork parameters (hemogram serum biochemistry analytes) were within normal limits. At the time of rescue bloodwork results indicated minor electrolyte abnormalities (hyponatremia, hypochloremia, hypoosmolality). Due to concerns for the dolphin's health a rescue was initiated. Here we review a case of an out-of-habitat subadult, female common bottlenose dolphin that remained in a freshwater lake in Seminole, Alabama for at least 32 days.
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