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Diseases of Aquatic Organisms

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DAO 134:99-106 (2019)  -  DOI: https://doi.org/10.3354/dao03346

Epizootic of multi-centric, squamous cell carcinomas in populations of Indo-Pacific humpbacked dolphins Sousa chinensis in Thai waters

Wijit Banlunara1,*, Somporn Techangamsuwan1,2,*, Nopadon Pirarat3, Theerayuth Kaewamatawong2, Chutchai Piewbang1, Sawang Kesdangsakonwut1, Thanida Haetrakul4, Nopphakarn Singkhum5, Nantarika Chansue4, Mary Miller6, Eric Lombardini6,**

1STAR Wildlife, Exotic and Aquatic Pathology, Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand
2Companion Animal Cancer Research Unit, Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
3Wildlife Exotic and Aquatic Animal Research Unit, Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
4Veterinary Medical Aquatic Animal Research Center, Faculty of Veterinary Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand
5Pattaya Dolphin World, Bang Lamung, Chon Buri Province 20150, Thailand
6Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok 10400, Thailand
*These authors contributed equally**Corresponding author:

ABSTRACT: Over the span of several years, 3 Indo-Pacific humpbacked dolphins died and were necropsied in Thailand. These 3 animals were all captive-bred at Oasis Sea World (Chanthaburi, Thailand), and displayed similar macroscopic progressive cutaneous lesions diagnosed as squamous cell carcinomas. In 2 of the 3 animals, necropsy revealed a severe fibrinosuppurative tracheitis and pneumonia secondary to metastasis of a cutaneous squamous cell carcinoma which extended from the head throughout the trunk and flippers. The tumors were characterized by coalescing botryoid masses with severe areas of cutaneous erosion, ulceration and necrohemorrhagic dermatitis. There was evidence of metastasis to the lungs and hilar lymph nodes. Necropsy of the third animal revealed similar progressive cutaneous squamous cell carcinomas but without evidence of metastasis. DNA molecular analysis of homogenized neoplastic tissue was conducted using polymerase chain reaction for both herpesvirus and papillomavirus in 2 of the 3 cases. In the first case, the tissues were positive for a herpesvirus alone, and this was phylogenetically classified as an alphaherpesvirus. This new herpesvirus has been tentatively named Sousa chinensis alphaherpesvirus. The second animal was negative for this novel herpesvirus and the third was not analyzed. In addition to the captive population, there is photographic evidence from 2 separate wild populations of Indo-Pacific humpbacked dolphins in the Gulf of Thailand, of a macroscopically identical proliferative and ulcerative process suspected to be squamous cell carcinomas.


KEY WORDS: Squamous cell carcinoma · Emerging infectious disease · Indo-Pacific humpbacked dolphin · Epizootic · Neoplasia · Oncogenic · Herpesvirus


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Cite this article as: Banlunara W, Techangamsuwan S, Pirarat N, Kaewamatawong T and others (2019) Epizootic of multi-centric, squamous cell carcinomas in populations of Indo-Pacific humpbacked dolphins Sousa chinensis in Thai waters. Dis Aquat Org 134:99-106. https://doi.org/10.3354/dao03346

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