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SURGICAL REMOVAL OF AN ABDOMINAL MYOSARCOMA IN A KOI (Cyprinus carpio) Gregory A. Lewbart, MS, VMD,* Gary Spodnick, DVM, Nancy E. Love, DVM, Norman Barlow, DVM, and Robert Bakal, DVM North Carolina State University, College of Veterinary Medicine, 4700 Hillsborough Street, Raleigh, NC 27606 USA Abstract A 3-yr-old mature male showa koi (Cyprinus carpio) weighing 1792 g presented in October of 1996 to the Veterinary Teaching Hospital of the College of Veterinary Medicine, North Carolina State University (CVM-NCSU) with a 2-mo history of a distended abdomen. Water quality parameters were within normal limits and the fish had been fed a diet of commercially prepared koi pellets on the fish farm where it lived. Multiple imaging procedures were performed to characterize the coelomic mass and to localize the organ of origin. Left to right lateral (RL) and right (RDL) and left (LLD) lateral decubital (horizontal beam) whole body radiographs, caudal coelomic cavity ultrasonography and computed tomography (CT) were performed. The fish was anesthetized for an exploratory celiotomy. Anesthesia was induced by immersing the fish in a 200 mg tricaine methanesulfonate (Finquel®, Argent Chemical Labs, Redmond, WA 98052 USA) solution/L water for 5 min until the fish had only mild opercular movements (the opercula could be observed moving but the motion was not sufficient to generate water flow across the gills). The fish was placed on the surgery area and the delivery tubes of a recirculating anesthesia machine were positioned into its mouth. A stock solution of tricaine methanesulfonate was prepared by dissolving 10 g Finquel® in 1 L of deionized water and buffering it to pH 7.0 with sodium bicarbonate. Anesthesia was maintained with a constant 160 mg/L tricaine methanesulfonate at a flow rate of 3 L/min for 55 min. The concentration of tricaine methanesulfonate was gradually reduced to 38 mg/L over the next 40 min as the surgical procedure was being completed. Total duration of anesthesia was 100 min. The patient was also given a 10 mg/kg intraperitoneal dose of enrofloxacin (Baytril®, Bayer Corp., Shawnee Mission, KS 66201 USA) during surgery to reduce the possibility of a secondary bacterial infection. Butorphanol tartrate (Torbutrol®, Fort Dodge Laboratories, Inc., Fort Dodge, IA 50501 USA) at a dose of 0.1 mg/kg was given subcutaneously at the end of the surgery for pain management. The scales were removed from the area of the planned incision site with forceps. A ventral midline abdominal incision was made beginning immediately caudal to the base of the pectoral fins and extended to within 1 cm of the cloaca. An osteotome was used to separate the pelvic girdle along its midline. Gelpi perineal retractors were used to maintain retraction of the coelomic incision. A large solid mass was present in the abdominal coelom extending caudally from the liver to the pelvic 1997 PROCEEDINGS AMERICAN ASSOCIATION OF ZOO VETERINARIANS 1 inlet, and was compressing the internal organs dorsally and to the left. Sharp and blunt dissection was used to free the mass from its attachments to the liver, body wall, and kidneys. Larger vessels supplying the mass were divided and ligated using 4-0 polypropylene (Prolene®, Ethicon, Somerville, NJ 08876 USA) suture and bipolar cautery was used to electrocoagulate smaller vascular pedicles. The pelvic osteotomy was repaired using 2-0 stainless steel cerclage wires. The muscle wall was closed with 3-0 polyglyconate (Maxon®, Davis & Geck, Manati, Puerto Rico 00701 USA) in a simple continuous pattern and the skin was closed with 4-0 polypropylene in a continuous Ford interlocking pattern. The fish recovered without complication from the anesthesia and surgical procedure. The air space in the coelomic cavity caused the fish to be positively buoyant, thus 110 ml of air was aspirated from the abdomen, correcting the problem. The skin sutures were removed 25 days post operatively. Microscopically the mass was identified as a myosarcoma but could not be morphologically distinguished as a rhabdomyosarcoma or a leiomyosarcoma. Immunohistochemistry and transmission electron microscopy results are pending. Myosarcomas are not common in fish but have been reported in an African lungfish (Protopterus dolloi) and a cutlass fish (Trichiurus lepturus).1,2 We found no reports of this tumor in koi or carp, but papillomas, squamous cell carcinomas, and a branchioblastoma have all been described in koi.4,5 Tricaine methanesulfonate is approved by the Food and Drug Administration (FDA) and is a widely used anesthetic for fishes.3 Most fish experience an excitatory stage of anesthesia followed by sedation, a loss of equilibrium and finally, a loss of any reactivity. It is desirable to maintain an anesthetic plane at this level. Mild opercular movements should be maintained and the gills must be bathed sufficiently with anesthetic water. Anesthetic effects of tricaine methanesulfonate are quickly reversed by diluting the concentration and placing the fish into a solution of fresh, clean water. The surgical removal of this tumor relieved unnatural pressure on the internal organs and the body wall. The fish appeared clinically normal 6 mo after the procedure. ACKNOWLEDGMENTS The authors thank Drs. Michael Stoskopf and Craig Harms for their assistance with case management. LITERATURE CITED 1. Endo M. 1991. Spontaneous tumors in the cutlass fish Trichiurus lepturus and the dusky spinefoot Siganus fuscescens. Japanese J. Ichthyology 37(4): 421-423. 2. Hubbard G.B. 1985. A seminoma and a leiomyosarcoma in an albino African lungfish (Protopterus dolloi). J. Wildl. Dis. 21(1): 72-74. 3. Stoskopf M.K. 1995. Anesthesia of pet fishes. In: Current Veterinary Therapy XII (Kirk and Bonagura eds.) Saunders Co., 1365-1369. 2 1997 PROCEEDINGS AMERICAN ASSOCIATION OF ZOO VETERINARIANS 4. Wildgoose W.H. 1992. Papilloma and squamous cell carcinoma in koi carp (Cyprinus carpio). Vet. Record 130: 153-157. 5. Wildgoose W.H. and D. Bucke. 1995. Spontaneous branchioblastoma in a koi carp (Cyprinus carpio). Vet. Record 136: 418-419. 1997 PROCEEDINGS AMERICAN ASSOCIATION OF ZOO VETERINARIANS 3 OVARIECTOMY OF A BROOK TROUT (Salvelinus fontinalis) M. Andrew Stamper, DVM1,2* and Terry Norton, DVM1,3 1Environmental Medicine Consortium, North Carolina State University, 4700 Hillsborough Street Raleigh, NC 27606 USA; 2Department of Companion Animal and Special Species Medicine, College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough Street Raleigh, NC 27606 USA; 3Hanes Veterinary Medical Center, North Carolina Zoological Park, 4401 Zoo Parkway Asheboro, NC 27203 USA Abstract A 1.7 kg mature female brook trout, Salvelinus fontinalis, was diagnosed with egg retention. Anesthesia was induced with 150 mg/ml of tricaine (Finquel®, Argent Chemical Labs, Redmond, WA 98052 USA) and the fish maintained at 75-95 mg/ml with a flow rate of 2 L/min using a recirculating machine.1,2 The fish was placed in dorsal recumbency in a custom water permeable open-cell foam rubber trough and the incision site covered by a fenestrated transparent surgical drape. A midline incision was made approximately 1 cm cranial to the pelvic girdle. Ovariectomy was performed by retracting each ovary individually to expose their respective dorsal mesovarium which was carefully dissected from the caudal pole of the ovary. The ovarian artery and vein were clamped with two mosquito forceps approximately 2 mm apart prior to placement of a transfixiation ligature using 4-0 polyglycolic acid (Dexon, Davis and Geck Inc., Manati, PR 00701) around the ovarian artery and vein between the two clamps. The vasculature was incised between the ligature and distal forceps. The body wall and coelomic musculature were sutured with a two layer closure using 4-0 polyglycolic acid in a simple-continuous patterns. The skin was sutured using 4-0 polyglycolic acid in a simple interrupted pattern. The trout recovered from anesthesia within 20 min, but residual air in the coelomic cavity following closure created a transient positive buoyancy which resolved within an hour. No other complications were noted and the fish resumed eating within 2 days. Sutures were removed 21 days later. Ovariectomy in fish is a viable option for display aquarium female fish with ovarian disease. LITERATURE CITED 1. Harms, C., and R.S. Bakal. 1995. Techniques in fish anesthesia. J. Sm. Exotic Anim. Med. 3:19-25. 2. Lewbart, G.A., E.A. Stone, and N.E. Love. 1995. Pneumocystectomy in a midas cichlid. J. Am. Vet. Med. Assoc. 207:319-321. 4 1997 PROCEEDINGS AMERICAN ASSOCIATION OF ZOO VETERINARIANS REPLACEMENT OF A PROLAPSED STOMACH IN A BANDED WOBBEGONG SHARK (Orectolobus ornatus) Frances Hulst, BVSc, MVS1* and Rupert Woods, BSc, BVMS, PhD, MVS2 1Veterinary and Quarantine Centre, Taronga Zoo, PO Box 20, Mosman, NSW, 2088, Australia; 2Veterinary Department, Western Plains Zoo, Obley Road, Dubbo, NSW, 2830, Australia Abstract A 48 kg, male, banded wobbegong shark (Orectolobus ornatus) presented with a history of having prolapsed its stomach through one of its gill slits 48 hr previously. The shark had been successfully kept in a 1.25 × 106 L mixed species oceanarium for several years prior to this. On examination, 20-30 cm of brown-purple tissue was protruding from the shark’s right caudal external gill slit. The animal was resting on the floor of the aquarium and there appeared to have been minor bleeding from the everted tissue. The wobbegong was anesthetized with 1,750 mg ketamine (36.5 mg/kg) (Ketamine HCl; 1 g powder Parke Davis, North Caringbah, New South Wales, Australia) combined with 500 mg xylazine (10.4 mg/kg) (Rompun Dry, 500 mg base, Bayer, Pymble, New South Wales, Australia) administered intramuscularly by a scuba diver using a pole syringe. Loss of righting reflex occurred after 12 min. Surgical anesthesia occurred after approximately 20 min and lasted about 50 min. The shark was placed in an isolation tank in 15 cm of water, allowing the gills to be covered.