Electrochemotherapy for the Treatment of Oral Squamous Cell Carcinoma in an Asian Small-Clawed Otter (Aonyx cinereus)
American Association of Zoo Veterinarians Conference 2019
Kailey B. Anderson1, DVM; Jessica Siegal-Willott1, DVM, DACZM; Christine H. Merrick2, DVM, DACVIM (Oncology); Amanda Foskett3, DVM, DACVIM (Oncology)
1Smithsonian National Zoological Park, Washington, DC, USA; 2Katonah Bedford Veterinary Center, Bedford Hills, NY, USA; 3Friendship Hospital for Animals, Washington, DC, USA


A 7-yr-old female Asian small-clawed otter (Aonyx cinereus) was evaluated for an oral mass and 2-wk history of altered chewing behavior. Biopsy and histopathology revealed a diagnosis of oral squamous cell carcinoma (SCC). Diagnostic computed tomography (CT) revealed a non-resectable, right-sided mass involving the tongue, ventral pharynx, and hyoid bones. Treatment options for oral SCC include surgical resection, radiation therapy, chemotherapy, or palliative care with non-steroidal anti-inflammatories.1,3,5 More recently, electrochemotherapy (ECT) was used for treatment of oral SCC in domestic dogs resulting in marked tumor responses (CM personal observation), and was used for treatment of cutaneous SCC and cutaneous papillomas in turtles.2,4 In this case, initial treatment included meloxicam (Meloxicam, Ceva Animal Health LLC, Lenex, KS, USA) 0.1 mg/kg PO, SID followed by three ECT treatments every 2–4 wks. For each ECT treatment, bleomycin (Bleomycin, Meitheal Pharmaceuticals, Chicago, IL, USA) 20 mg/m2 was administered intravenously 10 min prior to intralesional cisplatin (Cisplatin, Alvogen Inc., Pine Brook, NJ, USA) 0.2 mg/kg and delivery of biphasic electric pulses using reversible and irreversible electroporation. After treatment, the rostral aspect of the tumor regressed visibly, but recheck CT confirmed a poor response at the caudal aspect. ECT was discontinued due to the small size of the oral cavity precluding effective access and treatment of the caudal aspect of the tumor. Two months after the last ECT treatment and 7 mo after initial evaluation, the patient is doing well. ECT was effective in providing palliation, as well as marked tumor regression in the rostral aspect of the lesion. ECT should be considered in the treatment of oral SCC where the tumor is accessible to administration of ECT.


The authors would like to thank the curators and keepers at the National Zoological Park who cared for this animal.

Literature Cited

1.  Boria PA, Murrary DJ, Bennett PF, Glickman NW, Snyder PW, Merkel BL, Schlittler DL, Mutsaers AJ, Thomas RM, Knapp DW. Evaluation of cisplatin combined with piroxicam for the treatment of oral malignant melanoma and oral squamous cell carcinoma in dogs. J Am Vet Med Assoc. 2004;224(3):388–394.

2.  Brunner CHM, Dutra G, Silva CB, Silveira LMG, Martins MFM. Electrochemotherapy for the treatment of fibropapillomas in Chelonia mydas. J Zoo Wildl Med. 2014;45(2):213–218.

3.  Hayes A, Scase T, Miller J, Sparkes A, Adams V. COX-1 and COX-2 expression in feline oral squamous cell carcinoma. J Comp Pathol. 2006;135(2–3):93–99.

4.  Lanza A, Baldi A, Spugnini EP. Surgery and electrochemotherapy for the treatment of cutaneous squamous cell carcinoma in a yellow-bellied slider (Trachemys scripta scripta). J Am Vet Med Assoc. 2015;246(4):455–457.

5.  Wiles V, Hohenhaus A, Lamb K. Retrospective evaluation of toceranib phosphate (Palladia) in cats with oral squamous cell carcinoma. J Feline Med Surg. 2017;19(2):185–193.


Speaker Information
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Kailey B. Anderson, DVM
Smithsonian National Zoological Park
Washington, DC, USA

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