Abstract

Both in the wild and in professional care, cetaceans can develop a variety of ocular lesions, making ocular health an important part of overall health care.¹ In humans, ocular diseases are well known, being ocular melanoma the most frequent type of melanoma after cutaneous melanoma.^2,3 However, there are no reports of melanocytic tumors derived from eye-related injuries in dolphins.

Clinical Case

A female bottlenose dolphin (Tursiops truncatus) born in professional care presented a corneal lesion in the left eye following a trauma. Despite the ophthalmic treatment administered, the lesion continued to progress as a mass of granular tissue that over time covered the entire eyeball. Meanwhile, an area of approximately 10 x 10 cm swelling, hard at touch, developed in the palate. Given the discomfort associated with the lesion, the attitude and appetite of the specimen was intermittent. Skull radiographs were taken in several projections, revealing density changes in the area of the ocular orbit, as well as alterations in the symmetry compared to the contralateral side. Similarly, it was evident the presence of a circular radiopaque area in the maxilla that coincides with the swelling previously mentioned. Thermographic photos showed an increase in temperature in the affected area of the palate. Thus, a sample was collected via a fine needle aspiration (FNA). Microbiological culture of the sample resulted in sterility, and no other evident pathological changes were found in the cytology. Discomfort became evident when the specimen tried opening the mouth, as well as when grabbing the fish, resulting in difficulty for the animal to eat. Eventually, the tissue protruding the ocular lesion started bleeding, so subconjunctival injections of bevacizumab were administered once a week to reduce the vascularization in the area. Bleedings stopped with the second application of the treatment. In spite of the efforts, the body condition of the specimen gradually deteriorated and ultimately the specimen passed away. At necropsy, severe lesions were observed in the lungs and liver. The granular tissue involved the entire eyeball, and proliferated affecting the maxillary bone and through the left parietal, putting pressure on the encephalic mass. The histopathological diagnosis of the lesion indicated the presence of a poorly differentiated malignant melanoma with metastases to the lymph nodes, spleen, lungs, and affecting the bones. Although melanomas have been reported in other marine mammal species, up to our knowledge, this is the first reported case of a multimetastasic ocular melanoma in a bottlenose dolphin.^4-6

Acknowledgements

The authors would like to thank all trainers at Dolphin Discovery and Dr. David Espinosa Avilés for their help and expertise in this medical case.

*Presenting author

Literature Cited

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