OCCURRENCE OF VERTEBRAL OSTEOPHYTOSIS IN A MUSEUM SAMPLE OF WHITE-BEAKED DOLPHINS (LAGENORHYNCHUS ALBIROSTRIS) FROM DANISH WATERS

Abstract

The occurrence of pathologic new bone formation in the vertebral column was studied in 46 skeletons of the white-beaked dolphin (Lagenorhynchus albirostris) stranded in Denmark between 1903 and 2002 and held in the collections of the Zoological Museum, University of Copenhagen. New bone formation was evident in 18 (72%) of 25 physically mature specimens and in one of 21 physically immature specimens. This pattern of occurrence is consistent with spondylosis deformans, which is caused by degeneration of the intervertebral disk. In general, females seemed to be more susceptible, exhibiting a higher number of affected vertebrae and more severe cases. Lesions were predominantly detected in the lumbar and cranial caudal vertebra. Data on blubber thickness were available for part of the sample; one of the most heavily afflicted specimens had the thickest recorded blubber, indicating that secondary bone formation leading to blocks of fused vertebrae had not necessarily impaired the body condition of afflicted specimens. However, age determinations conducted on the sample revealed that none of the most severe cases occurred among the oldest animals, implying that these severe cases may cause premature fatality.