Ballard sea lion necropsy findings
Apr/21/10 12:35 PM
On Tuesday, April 20th, a thorough examination was performed by Washington Department of Fish and Wildlife and Cascadia Research on the adult male California sea lion that stranded live at Golden Gardens on Sunday, April 18th. The preliminary findings are as follows:
Total body radiographs (x-rays) taken at Pt. Defiance Zoo and Aquarium did not reveal any evidence that it had been shot. However, there appeared to be some abnormalities in the chest cavity, confirmed upon necropsy by the finding of a fractured sternum between ribs four and five and a significant amount of hemorraging (bruising) into the surrounding muscle. The fractured sternum was placing pressure on the aorta/heart, causing some of the small arteries around the heart and pericardium to rupture, which resulted in internal bleeding into the chest cavity and the subsequent death of the animal.
A fractured sternum is typically attributed to blunt force trauma and likely was the cause of the sea lion stranding. This would also have contributed to his difficulty moving while on the beach and the abnormal behavior of not returning to the water. There are a number of circumstances which could have caused the blunt force trauma - boat collision or another type of negative human interaction, transient orca attack, a fight with another sea lion, a fall from a rocky resting spot, etc. The external injuries, which were noted on the beach, were determined to be old wounds that had healed.
The thorough examination resulted in the collection of a large number of samples for additional analyses including examination for pathology, microbiology, bioxtoxins, and contaminants. These results will not be known for weeks or months, but may provide additional insights not only into the cause of death but into the overall health of this sea lion.
Total body radiographs (x-rays) taken at Pt. Defiance Zoo and Aquarium did not reveal any evidence that it had been shot. However, there appeared to be some abnormalities in the chest cavity, confirmed upon necropsy by the finding of a fractured sternum between ribs four and five and a significant amount of hemorraging (bruising) into the surrounding muscle. The fractured sternum was placing pressure on the aorta/heart, causing some of the small arteries around the heart and pericardium to rupture, which resulted in internal bleeding into the chest cavity and the subsequent death of the animal.
A fractured sternum is typically attributed to blunt force trauma and likely was the cause of the sea lion stranding. This would also have contributed to his difficulty moving while on the beach and the abnormal behavior of not returning to the water. There are a number of circumstances which could have caused the blunt force trauma - boat collision or another type of negative human interaction, transient orca attack, a fight with another sea lion, a fall from a rocky resting spot, etc. The external injuries, which were noted on the beach, were determined to be old wounds that had healed.
The thorough examination resulted in the collection of a large number of samples for additional analyses including examination for pathology, microbiology, bioxtoxins, and contaminants. These results will not be known for weeks or months, but may provide additional insights not only into the cause of death but into the overall health of this sea lion.
