Abstract: Pathological findings associated with the mass stranding of five melon-headed whales (Peponocephala electra) along the Atlantic coast of Florida are reported. Four of the five whales were freshly dead, and the fifth was moderately decomposed. Body weights ranged from 160 to 180 kg, and all whales had mild to moderate weight loss evidenced by postnuchal depression and pronounced scapulae and peduncular vertebrae. All whales had from 10 to 21 ovoid dermal scars consistent with healed cookie-cutter shark (Isistius brasiliensis) wounds. Gastric compartments of all whales contained from 6 to 20 squid beaks with no other solid food items present. The peritoneum of all whales contained many parasitic cestode cysts consistent with Monorygma spp. In all cases, the alimentary tract had gross and microscopic lesions. Colons had an unusual microscopic lesion diagnosed as particularly florid examples of the collagenous stage of microscopic colitis known as collagenous colitis as reported in humans. The lesion was characterized by a diffuse, irregular, moderate thickening of the colonic wall due to deposition of subepithelial collagen between the muscularis mucosae and basement membrane of the surface epithelium in the lamina propria. The surface epithelium and collagen layer had mild multifocal infiltrates of neutrophils and eosinophils and mildly increased numbers of lymphocytes and plasma cells. Additionally, mild to moderate myocardial degeneration was a consistent finding in all cases. Less consistent lesions included erosive esophagitis, ulcerative gastritis, granulomatous gastritis, ulcerative dermatitis, and Nasitrema-associated suppurative sinusitis. The cause of the mass stranding was not determined; however, all whales exhibited pathological changes consistent with pre-existing chronic disease with inanition that developed prior to the stranding event.

Key Words: MELON-HEADED WHALE; PEPONOCEPHALA ELECTRA; PATHOLOGY; MASS STRANDING; FLORIDA

Document Type: Research article

DOI: 10.1578/AM.33.2.2007.235

Page Numbers: 235 - 240

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