Use of Piroxicam as a Treatment for an Oral Squamous Cell Carcinoma in a Bottlenose Dolphin (Tursiops aduncus)
The occurrence of squamous cell carcinoma is a well-documented disease process in both wild and captive populations of bottlenose dolphins (Tursiops truncatus).1 Described treatment regimens for this disease include excision,2 laser therapy,3 intralesional chemotherapy,4 cryotherapy, brachytherapy5 and maintenance with herbal supplementation6.
The non-steroidal anti-inflammatory piroxicam has been shown to have potential anti-neoplastic properties7 and has been successfully used to treat multiple neoplastic conditions in domestic animals including oral squamous cell carcinomas8.This treatment has not been previously described in bottlenose dolphins, possibly because of the sensitivity of this species to non-steroidal anti-inflammatories.9
In 2008 a 38-year male dolphin presented with an ulcerative mass on the soft palate that was biopsied and diagnosed as an infiltrative squamous cell carcinoma. Numerous papillomatous lesions were also present on the frenulum in the intermandibular space. These lesions were treated with cryotherapy. The size and location of the lesion on the soft palate precluded surgical excision and intralesional chemotherapy and brachytherapy were discounted for logistical concerns surrounding public and employee safety. A trial treatment regime was created using piroxicam at a dose rate of 0.15 mg/kg twice daily for a period to be determined based on the animal's response to treatment. Concurrent therapy with 200 µg of misoprostol four times daily was used to prevent gastric ulceration and doxycycline added at 2 mg/kg once daily for microbial protection. The animal appeared unwell after a four-day period of treatment and medication was halted. The animal's condition improved and routine blood collection showed no signs of gastrointestinal ulceration or renal toxicity. Treatment was recommenced after a 48-hour spell and continued for a further 10 days. Treatment was concluded at this time following an unacceptable decline in the animal's condition and the observation of melena, presumably indicative of gastric ulceration. Weekly bloods were collected prior to, during and post-treatment to assess renal health and no significant findings were detected.
The mass on the soft palate reduced in size markedly over the 2-week period. Subsequent biopsies from the area have been indicated on occasion and have detected atypical squamous epithelium, consistent with a squamous cell carcinoma; however, the lesion has not progressed grossly. The lesions on the frenulum cranial to the tongue continue to be treated periodically with cryotherapy. The animal remains in good health 5 years after treatment.
We would like to thank Symbion Vetnostics, for providing pathological interpretation of samples submitted.
* Presenting author
1. Bossart GD, Ghim SJ, Rehtanz M, Goldstein J, Varela R, Ewing RY, Fair PA, Lenzi R, Joseph B, Hicks CL, et al. Orogenital neoplasia in Atlantic bottlenose dolphins (Tursiops truncatus). Aquat Mammals. 2005; 31(4):473–480.
2. Doescher BM, Sanchez R, Lopez A, Browning P, Lenzi R, Pawloski J, Renner MS, Bossart GD. Radical surgical excision of an oral squamous cell carcinoma lesion in an Atlantic bottlenose dolphin (Tursiops truncatus). In: Proceedings from the 38th Annual IAAAM Conference; May 5–9, 2007; Lake Buena Vista, FL, USA; pp. 210–211.
3. McKinnie CJ, Dover SR. Diagnosis and treatment of lingual carcinoma in an Atlantic bottlenose dolphin (Tursiops truncatus). In: Proceedings from the 34th Annual IAAAM Conference; May 10–14, 2003; Kohala Coast, HI, USA; pp. 164–165.
4. McKinnie CJ, Dover SR, Ogilvie G, Bossart GD. Treatment of oral squamous cell carcinoma in an Atlantic bottlenose dolphin. In: Proceedings from the 32nd Annual IAAAM Conference; April 28–May 2, 2001; Tampa, FL, USA; pp. 37–38.
5. McKinnie CJ, Dube S, Fitzgerald RB, Conant J, French B, Lederer JL. Permanent I-125 seed implant in the treatment of squamous cell carcinoma in an Atlantic bottlenose dolphin (Tursiops truncatus). In: Proceedings from the 36th Annual IAAAM Conference; May 14–19, 2005; Seward, AK, USA; pp. 210–211.
6. Clemons-Chevis CL, Clough P, Xie H. The use of traditional Chinese herbal formulas in the long-term management of an Atlantic bottlenose dolphin (Tursiops truncatus) with oral squamous cell carcinoma. In: Proceedings from the 43rd Annual IAAAM Conference; May 12–16, 2012; Atlanta, GA, USA; pp. 206–208.
7. Earnet DL, Hixson LJ, Alberts DS. Piroxicam and other cyclooxygenase inhibitors: potential for cancer chemoprevention. J Cell Biochem. 1992;50(Suppl 16I):156–166.
8. Schmidt BR, Glickman NW, DeNicola DB, Gortari AE, Knapp DW. Evaluation of piroxicam for the treatment of oral squamous cell carcinoma in dogs. J Am Vet Med Assoc. 2001;218:1783–1786.
9. Blyde D, Vogelnest L. Cetaceans. In: Vogelnest L, Woods R, eds. Medicine of Australian Mammals. CSIRO Publishing; 2008:592–614.