Abstract

Fish medicine and surgery on fishes has become more common in veterinary practice in recent years. Receptive veterinary practices are being presented with more opportunity to see fish cases as clients want to care for their aquatic family members. Surgical intervention for treatment of neoplasia has been well reported in koi to include excision of ovarian tumors, nephroblastoma, leiomyoma, and undifferentiated sarcoma.^1,2,3,4,5 Leukemia and hepatocellular neoplasia are reported in bowfin (Amia calva)^6,7 and a testicular leiomyoma is reported in largemouth bass (Micropterus salmoides)⁸. However, none of these cases involved surgery.

This report summarizes the surgical management of neoplasia diagnosed in two fish. A mature bowfin of unknown age and sex presented for a focal distension of the left caudal ventrolateral coelom. Diagnostic imaging included computed tomography and ultrasound to reveal a focal expansile muscular mass adjacent to the left body wall at the level of the pectoral fin. A ventral midline intracoelomic approach allowed for isolation and excision of the intramuscular mass to include the adjacent peritoneum. Histologic evaluation reported the mass as a malignant melanophoroma with intramuscular invasion. No recurrence has been noted since final incision healing and release into communal enclosure 9 months ago. The second case, an unknown sex, mature largemouth bass, presented from the same enclosure for focal swelling of the left side cranial to the pelvic fin. Diagnostic imaging included ultrasound to identify tumor margins and facilitate a Tru-Cut® biopsy, which defined the mass as a soft tissue sarcoma. Surgical excision via a left lateral approach was completed on 7 September, 2016 and histologic evaluation corroborated the biopsy diagnosis. No recurrence is reported at the time of this presentation.

To the authors' knowledge this is the first reported successful treatment of these tumors by surgical intervention from these species. While reporting another type of tumor in a new species may not be of broad interest, reaffirming options for advanced diagnostic imaging and surgical intervention as an option for definitive treatment of neoplasia in client owned fish is important. Data reported in this case series represent continued improvements in the practice of fish medicine.

Acknowledgements

We thank Bass Pro Shops Inc., the Cary, North Carolina Bass Pro Shop Aquarists and staff, the NCSU Diagnostic Imaging Service, Kent Passingham, Macy Trosclair, Jane Christman, and Chelsey Vanetten.

Literature Cited

1.  Lewisch E, Reifinger M, Schmidt P, El-Matbouli M. 2014. Ovarian tumor in a koi carp (Cyprinus carpio) diagnosis, surgery, postoperative care and tumour classification. Tierärztliche Praxis Kleintiere. 42(4):257–262.

2.  Raidal SR, Shearer PL, Stephens F, Richardson J. 2006. Surgical removal of an ovarian tumour in a koi carp (Cyprinus carpio). Aqua Anim. 84:178–181.

3.  Stegeman N, Heatley JJ, Rodrigues A, Pool R. 2010. Nephroblastoma in a Koi (Cyprinus carpio). J Ex Pet Med. 19(4):298–303.

4.  Vergneau-Grosset C, Summa N, Rodriguez Jr CO, Cenani A, Sheley MF, McCarthy MA, Tanner JCM, Phillips KL, Hunt GB, Groff JM. 2016. Excision and subsequent treatment of a leiomyoma from the periventiduct of a koi (Cyprinus carpio koi). J Ex Pet Med. 25:194–202.

5.  Lewbart GA, Spodnick G, Barlow N, Love NE, Geoly F, Bakal RS. 1998. Surgical removal of an undifferentiated abdominal sarcoma from a koi carp (Cyprinus carpio). Vet Record. 143:556–558.

6.  Anderson WI, Luther PB. 1987. Poorly differentiated granuloplastic leukaemia in a bowfin, Amia calva L. J Fish Dis. 10:411–413.

7.  Maccubbin AE, Black J, Harshbarger JC. 1987. A case report of hepatocellular neoplasia in bowfin, Amia calva L. J Fish Dis. 10:329–331.

8.  Herman RL, Landolt M. 1975. A testicular leiomyoma in a largemouth bass, Micropterus salmoides. J Wild Dis. 11(1):128–129.