Abstract

Cetaceans are known to be challenged with a number of neoplastic diseases that include but are not limited to papilloma, leiomyoma, fibroma, hemangioma, adenoma, adenocarcinoma, squamous cell carcinoma (SCC) and lymphoma.¹ For the clinician the frequency of many tumor types is low though oral tumors such as squamous cell carcinoma make up a larger proportion and frequency in many locations. Clinical presentations of orogenital lesions in dolphins occur in both wild and managed individuals with varying degrees of severity and progression.² Oral lesion characteristics depend on the stage, often progressing from glossitis with minimal visual changes to papillomatosis then to squamous cell carcinoma. Early mucosal changes (slight swelling of the frenulum tissue or small red discoloration of the tongue) may be missed until more obvious changes are present such as small growths and ulcerations locally. The formation of larger tongue ulcerations to submucosal masses and oral deformity signals a later stage of the disease process. While inclusion bodies may help to direct the consideration of a viral etiology PCR has shown the presence of both herpes and papilloma virus leaving open the consideration for mixed etiologic agent involvement.³

Areas for improvement clinically include the need for dispersal of visual staging characteristics to encourage early intervention with the varying levels of experience in some facilities. Anecdotal information suggests a strong correlation with other factors such as hormonal receptors with exacerbation of lesions during pregnancy and possibly cycling. Therapeutic choices currently rely more on cryosurgery of areas of involvement with ulcerations and mucosal anomalies progressing to surgical removal of thickened areas including discreet masses. Laser therapy and other modalities have also been administered.⁴ Chemotherapy has been utilized including intratumoral injections of SCC masses with carboplatin, mucosal antiangiogenesis therapy and piroxicam orally.^5,6 Other approaches need to be considered to incorporate new compounds.

Diagnostically effort is being expended to quantitate herpes and papilloma virus involvement as well as receptor and IHC development. This will help to focus etiologic contributions and support additional therapeutic considerations. Proper sampling protocols that differ from classic diagnostic approaches are desires. Fresh deep frozen tumor samples are needed to cover variations in tissue response as well as fresh histologic samples that are set up with minimal formalin exposure for additional testing.

Acknowledgements

We wish to express our deep appreciation for the efforts of numerous participants for sending samples such as SeaWorld, Atlantis and other future partners. There are many who are helping to start these efforts and will be included as future coauthors.

* Presenting author

Literature Cited

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2.  Bossart GD, Ghim SJ, Rehtanz M, et al. 2005. Orogenital neoplasia in Atlantic bottlenose dolphins (Tursiops truncatus). Aquat Mamm. 31(4):473–480.

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6.  Duan T, March, DT, Bossart GD. 2014. Use of piroxicam as a treatment for an oral squamous cell carcinoma in a bottlenose dolphin (Tursiops aduncus). From the IAAAM 45th Annual Conference Proceedings, Gold Coast, Australia.