A 12-year-old female shusui koi (Cyprinus carpio) that weighed 10.3 kg (22.7 lb) was examined by the University of Georgia Zoological Medicine Service because of an ulcerated mass located ventral and lateral to the dorsal fin on the left body wall (Figure 1) The mass was first noticed 1 month prior to examination and, during the intervening period, had increased in size and become ulcerated, which resulted in the patient having a decreased appetite and activity level. The fish was maintained with 30 other female koi of similar size in a 114-kL (30,000-gallon) pond with appropriate mechanical and biological filtration, protein skimmers, and UV sterilization. Water-quality variables were checked daily, and no problems were identified (ie, ammonia, nitrite, and nitrate concentrations were undetectable; pH = 7.5; and dissolved oxygen concentration, 10 mg/L). Water temperature was maintained at 18.3°C (65°F) during the winter. The patient had no history of previous medical problems and had not spawned. The patient and its pond mates were fed a commercial pelleted rationa for koi that contained 45% protein during peak season (the warmer months of the year when increased feeding and optimal growth occur) and 36% protein in the spring and fall. No deaths had been reported for the pond population in the months leading up to the patient being examined, aside from a female koi that was euthanized because of an ovarian adenocarcinoma.
Photograph of a 12-year-old 10.3-kg (22.7-lb) female shusui koi (Cyprinus carpio) that depicts a raised, ulcerated, subcutaneous mass (arrows) ventral and lateral to the dorsal fin on the left body wall. Inset—Photograph of the ulcerated mass obtained looking at the dorsal aspect of the fish. Notice the mass is protruding from the left body wall (bottom) lateral to the dorsal fin.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Photograph of a 12-year-old 10.3-kg (22.7-lb) female shusui koi (Cyprinus carpio) that depicts a raised, ulcerated, subcutaneous mass (arrows) ventral and lateral to the dorsal fin on the left body wall. Inset—Photograph of the ulcerated mass obtained looking at the dorsal aspect of the fish. Notice the mass is protruding from the left body wall (bottom) lateral to the dorsal fin.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Photograph of a 12-year-old 10.3-kg (22.7-lb) female shusui koi (Cyprinus carpio) that depicts a raised, ulcerated, subcutaneous mass (arrows) ventral and lateral to the dorsal fin on the left body wall. Inset—Photograph of the ulcerated mass obtained looking at the dorsal aspect of the fish. Notice the mass is protruding from the left body wall (bottom) lateral to the dorsal fin.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
For transport to the University of Georgia Veterinary Teaching Hospital, the patient was removed from its home pond with a net and placed into a heavy-duty double bag that contained 50 L of preoxygenated water and was inflated with 100% oxygen. The bag was then placed in an insulated container. The patient was transported for 6 hours by air and van to a local wholesale facilityb for koi in Watkinsville, Ga, where it was allowed to rest and reacclimate for 2 days. The patient was prepared for transport as previously described and transported by van for 30 minutes to the teaching hospital for examination.
To facilitate examination, blood sample collection, and diagnostic imaging, the patient was anesthetized with a 10% eugenol solutionc in water (dose, 50 mg of eugenol/L of water). Anesthesia induction was smooth and uneventful. While the patient was anesthetized, opercular movements were visually monitored and ranged between 25 and 60 opercular movements/min, and heart rate, which was monitored by Doppler probe, ranged from 60 to 63 beats/min. Physical examination revealed an approximately 7 × 5-cm smooth, ulcerated, firm mass that elevated the overlying skin on the left dorsolateral aspect of the body wall ventral to the dorsal fin. On palpation, the mass extended deep to the subcutis and medially toward the dorsal vertebral spinous processes. The remainder of the physical examination was unremarkable.
A blood sample (approximately 3 mL) was obtained from the caudal vein for hematologic and plasma biochemical analyses. Hematologic results revealed moderate leukopenia (WBC count, 10,900 WBCs/μL; reference range, 19,800 to 28,100 WBCs/μL) characterized by mild neutrophilia (neutrophil count, 5,990 neutrophils/μL; reference range, 1,570 to 3,900 neutrophils/μL), marked lymphopenia (lymphocyte count, 3,920 lymphocytes/μL; reference range, 14,700 to 23,500 lymphocytes/μL), and slight monocytosis (monocyte count, 981 monocytes/μL; reference range, 460 to 960 monocytes/μL).1 For a teleost, those results were considered most consistent with a stress leukogram rather than a systemic bacterial infection.2–7 Plasma biochemical results revealed moderate hypercalcemia (calcium concentration, 17.3 mg/dL; reference range, 9.9 to 10.6 mg/dL), hyperphosphatemia (phosphorus concentration, 11.6 mg/dL; reference range, 4.3 to 5.5 mg/dL), and moderate hypercholesterolemia (cholesterol concentration, 319 mg/dL; reference range, 152 to 175 mg/dL).8 In teleosts, high plasma calcium concentrations can be associated with ovarian maturation and reproductive activity, high dietary calcium content, calcium concentration in the water, hemolysis-induced artifact, or handling and stress-induced osmoregulatory and metabolic dysfunction.9–12 Hyperphosphatemia can be caused by high dietary phosphorus content, phosphorus concentration in the water, hemolysis-induced artifact, or handling and stress-induced osmoregulatory and metabolic dysfunction.9,11 Hypercholesterolemia is associated with handling, hypoxic stress, water temperature, seasonal pattern, dietary cholesterol content, and age, sex, and size of the fish.13–15 For this particular patient, the plasma biochemical abnormalities were attributed to stress associated with handling and the long-distance transport. Other differential diagnoses for the plasma biochemical derangements observed included physiologic changes owing to reproductive activity (given the patient's age and sex), dietary influences, and sample handling. None of those differential diagnoses precluded the patient from undergoing anesthesia, advanced diagnostic imaging, or surgery.
Computed tomographic scans were obtained before and after contrast medium administration to better characterize the tissue type and vascularity of the mass, to determine its involvement with underlying structures, and for surgical planning purposes. The patient was positioned in dorsal recumbency and immobilized in a trough covered with damp towels. Owing to the inherent constraints of performing CT scans on a teleost, anesthesia was maintained by regular, manual bathing of the gills with an anesthetic solution (45 to 50 mg eugenol/L of oxygenated water) by use of 60-mL syringes. A whole-body CT scan was performed by use of a 64-slice helical scannerd with the following parameters: spiral pitch, 0.8; kV, 120; mAs, 250; and a matrix of 512 × 512. Images were reconstructed with medium-frequency (soft tissue) and high-frequency (bone) algorithms with a slice thickness of 0.6 mm in transverse, sagittal, and dorsal plane sequences. The postcontrast scans were acquired approximately 10 (arterial phase) and 150 seconds (delay phase) after manual injection of iohexole (1.71 mL/kg [0.77 mL/lb]; 350 mg of iodine/mL) into the caudal vein by use of a 21-gauge butterfly catheter. The duration required for pre- and postcontrast CT image acquisition was 9 minutes, and the total duration of the CT procedure (including setup) was approximately 25 minutes.
Postcontrast CT images revealed that most of the contrast material had extravasated from the caudal vein, to the left of midline. Consequently, there was limited vascular and parenchymal uptake of the contrast material on the arterial and delay-phase images.
At the caudal aspect of the dorsal fin, to the left of midline, dorsal to the vertebral canal, and lateral to the vertebral spines, there was a homogenous fat-opaque mass (5.1 × 3.9 × 7.1 cm) within the muscle. The mass was encased by a uniformly thin, well-defined capsule and contained a central septation (Figure 2) The fat portion of the mass was not contrast enhanced (−95 HU), but there was mild contrast enhancement of the capsule wall (42 to 52 HU). The remaining musculoskeletal and intracoelomic structures were unremarkable on the CT images. The primary differential diagnosis for the mass was lipoma, with liposarcoma being less likely given the relatively homogeneous attenuation and well-defined borders of the mass.
Postcontrast transverse (A) and sagittal (B) CT images viewed in a soft tissue window of the fish of Figure 1. There is a well-defined fat-opaque mass (asterisk) present in the left epaxial muscles. Extravasated contrast medium is present (black arrowheads) in the caudal aspect of the tail.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Postcontrast transverse (A) and sagittal (B) CT images viewed in a soft tissue window of the fish of Figure 1. There is a well-defined fat-opaque mass (asterisk) present in the left epaxial muscles. Extravasated contrast medium is present (black arrowheads) in the caudal aspect of the tail.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Postcontrast transverse (A) and sagittal (B) CT images viewed in a soft tissue window of the fish of Figure 1. There is a well-defined fat-opaque mass (asterisk) present in the left epaxial muscles. Extravasated contrast medium is present (black arrowheads) in the caudal aspect of the tail.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Immediately following completion of the CT procedure, the patient was positioned in sternal recumbency on a recirculating-water anesthesia table for fish. Anesthesia was maintained by use of a water pump and 2 hoses, which were placed in the mouth of the patient to provide active flow of the anesthetic solution (45 mg eugenol/L water) over the gills. Ultrasonographic evaluation of the mass was performed with a 9- to 11-MHz linear transducer.f The mass was diffusely heterogeneous with an echogenicity similar to fat and had a well-defined capsule with internal septation (Figure 3) The mass had poor central and peripheral vascularity on Doppler interrogation. Ultrasound-guided needle biopsyg specimens of the mass were then obtained for histologic and microbiological analyses. The ultrasonographic examination and biopsy procedure required a total of 15 minutes. The patient was placed in clean preoxygenated water to recover from anesthesia after the completion of the diagnostic procedures. Complete anesthetic recovery occurred within 10 minutes, without any complications. The patient was discharged into the care of the local koi wholesaler who provided suitable off-site holding facilities and care until laboratory results became available.
Transverse ultrasonographic image of the left-sided epaxial mass of the fish of Figure 1. The mass is encapsulated (arrowheads), has an internal septum, and has a similar echogenicity to fat. Dorsal is to the left.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Transverse ultrasonographic image of the left-sided epaxial mass of the fish of Figure 1. The mass is encapsulated (arrowheads), has an internal septum, and has a similar echogenicity to fat. Dorsal is to the left.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Transverse ultrasonographic image of the left-sided epaxial mass of the fish of Figure 1. The mass is encapsulated (arrowheads), has an internal septum, and has a similar echogenicity to fat. Dorsal is to the left.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Histologic examination of the biopsy specimens revealed normal adipose tissue without any evidence of an infectious or inflammatory process. On the basis of the presence of normal adipocytes and absence of neoplastic cells, a lipoma was suspected; however, a liposarcoma could not be definitively ruled out owing to the small specimen size. Microbiological evaluation revealed no fungal or bacterial growth.
The patient was brought back to the teaching hospital 1 week later for surgical excision of the suspected lipoma. Anesthesia was induced (50 mg of eugenol/L of water) and maintained (40 mg of eugenol/L of water) with eugenol in water by use of a recirculating anesthesia system as previously described. Cefazolinh (25 mg/kg [11.4 mg/lb], IV in the caudal vein) was administered intraoperatively. Perioperative analgesia was initiated with butorphanol tartratei (0.4 mg/kg [0.18 mg/lb], IM). The fish was positioned in sternal recumbency and draped with wet towels. The surgical site was isolated with sterile hand towels soaked in sterile saline (0.9% NaCl) solution. A sterile cotton-tipped applicator soaked in sterile saline solution was used to wipe along the planned incision site once to remove the surface mucus.
A No. 15 scalpel blade was used to make an approximately 15-cm curvilinear full-thickness incision over the mass, ventral to the ulcerated region. Metzenbaum scissors were used to bluntly dissect the integument from the dorsal and lateral aspects of the mass. Digital dissection was then used to separate the rest of the tumor from the adjacent tissues until it could be removed en bloc (Figure 4) A single blood vessel arising between the dorsal vertebral processes was cauterized by use of a bipolar radiosurgical unit.j The surgical site and tumor cavity were copiously lavaged with sterile saline solution as described.16 No attempt was made to fill or reduce dead space because external water pressure would prevent seroma formation. The thin, superficial muscle and dermis were closed with 2-0 absorbable triclosan-impregnated poliglecaprone 25 suturek in a simple continuous pattern. The skin was then carefully apposed with 2-0 absorbable triclosan-impregnated poliglecaprone 25 suturek in a simple interrupted pattern. As surgery neared completion, the concentration of eugenol used to maintain anesthesia was gradually lowered in a stepwise manner (ie, from 40 to 35 to 30 to 25 mg of eugenol/L of water) before being discontinued. Recovery from anesthesia was uneventful, and there were no anesthetic or intraoperative complications.
Photographs depicting surgical removal of the mass from the fish of Figure 1. A—Photograph of the patient positioned in sternal recumbency on the surgery table. The fish was anesthetized with a solution of eugenol in water by use of a water recirculation circuit. The anesthetic solution was pumped from the glass tank under the surgery table to the table surface and over the patient's gills, then allowed to drain back into the tank. The surgical field was isolated with sterile hand towels soaked in sterile saline (0.9% NaCl) solution. The surgeon is wiping the intended incision line with a sterile cotton-tipped applicator soaked in sterile saline solution to remove the surface mucus from the skin. B—Photograph of a curvilinear skin incision being made along the ventral border of the mass. C—Photograph of the mass being removed by blunt digital dissection. D—Photograph of the surgical site following removal of the mass. No attempt was made to fill or reduce the resultant dead space because external water pressure would prevent seroma formation. E—Photograph of the surgical site following closure of the skin with 2-0 triclosan-impregnated poliglecaprone 25 suture in a simple interrupted pattern. The sutures were removed during a recheck appointment 5 weeks after surgery.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Photographs depicting surgical removal of the mass from the fish of Figure 1. A—Photograph of the patient positioned in sternal recumbency on the surgery table. The fish was anesthetized with a solution of eugenol in water by use of a water recirculation circuit. The anesthetic solution was pumped from the glass tank under the surgery table to the table surface and over the patient's gills, then allowed to drain back into the tank. The surgical field was isolated with sterile hand towels soaked in sterile saline (0.9% NaCl) solution. The surgeon is wiping the intended incision line with a sterile cotton-tipped applicator soaked in sterile saline solution to remove the surface mucus from the skin. B—Photograph of a curvilinear skin incision being made along the ventral border of the mass. C—Photograph of the mass being removed by blunt digital dissection. D—Photograph of the surgical site following removal of the mass. No attempt was made to fill or reduce the resultant dead space because external water pressure would prevent seroma formation. E—Photograph of the surgical site following closure of the skin with 2-0 triclosan-impregnated poliglecaprone 25 suture in a simple interrupted pattern. The sutures were removed during a recheck appointment 5 weeks after surgery.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Photographs depicting surgical removal of the mass from the fish of Figure 1. A—Photograph of the patient positioned in sternal recumbency on the surgery table. The fish was anesthetized with a solution of eugenol in water by use of a water recirculation circuit. The anesthetic solution was pumped from the glass tank under the surgery table to the table surface and over the patient's gills, then allowed to drain back into the tank. The surgical field was isolated with sterile hand towels soaked in sterile saline (0.9% NaCl) solution. The surgeon is wiping the intended incision line with a sterile cotton-tipped applicator soaked in sterile saline solution to remove the surface mucus from the skin. B—Photograph of a curvilinear skin incision being made along the ventral border of the mass. C—Photograph of the mass being removed by blunt digital dissection. D—Photograph of the surgical site following removal of the mass. No attempt was made to fill or reduce the resultant dead space because external water pressure would prevent seroma formation. E—Photograph of the surgical site following closure of the skin with 2-0 triclosan-impregnated poliglecaprone 25 suture in a simple interrupted pattern. The sutures were removed during a recheck appointment 5 weeks after surgery.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Results of histologic evaluation of the mass were most consistent with a lipoma. The unencapsulated expansile mass was composed of sheets of well-differentiated adipocytes, which were round and had abundant cytoplasm with a single clear vacuole (lipid) that displaced and flattened the nucleus. There was mild anisokaryosis and anisocytosis. No mitotic figures were observed. Well-differentiated adipocytes dissected layers of skeletal myocytes within a small portion of adhered muscle tissue. Those adipocytes likely represented normal adipocytes, but an infiltrative lipoma could not be definitively ruled out on the basis of histologic examination. Adipocytes extended to cut borders of the mass (Figure 5)
Photomicrograph of a section of the mass removed from the fish of Figure 1. The mass was composed of sheets of well-differentiated adipocytes. Each adipocyte had abundant cytoplasm with a single 30- to 300-μm clear lipid vacuole that flattened and peripheralized the nucleus. Histologic findings were consistent with a diagnosis of benign lipoma. H&E stain; bar = 200 μm.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Photomicrograph of a section of the mass removed from the fish of Figure 1. The mass was composed of sheets of well-differentiated adipocytes. Each adipocyte had abundant cytoplasm with a single 30- to 300-μm clear lipid vacuole that flattened and peripheralized the nucleus. Histologic findings were consistent with a diagnosis of benign lipoma. H&E stain; bar = 200 μm.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Photomicrograph of a section of the mass removed from the fish of Figure 1. The mass was composed of sheets of well-differentiated adipocytes. Each adipocyte had abundant cytoplasm with a single 30- to 300-μm clear lipid vacuole that flattened and peripheralized the nucleus. Histologic findings were consistent with a diagnosis of benign lipoma. H&E stain; bar = 200 μm.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Postoperative care consisted of placing the fish in water with 0.3% salinity for 3 weeks following surgery to reduce the osmotic stress on the patient and pathogen load at the surgical site.17–21 Because the surgical procedure was performed aseptically, postoperative antimicrobial administration was not indicated. Administration of postoperative analgesics would have been ideal but was considered impractical owing to the limitations of accessibility at the holding facility and concern about causing additional stress to the patient. Immediately after the patient was returned to the holding tank following surgery, improvements in appetite and activity were seen, but no signs of pain or discomfort were noted.
Following surgery, the patient was housed at the wholesaler facility for 5 weeks and then was reevaluated at the teaching hospital. Transport, anesthesia, and the acquisition of noncontrast-enhanced CT images were performed as previously described. The surgical site had healed with no signs of dehiscence and minimal scarring. The CT images indicated that the intramuscular lipoma in the left dorsal body wall was absent, and the regional epaxial muscles were only marginally reduced in size with interrupted fascial planes. The cutaneous tissues were concave with a mildly irregular margin, consistent with the surgical approach. There was no evidence of mass regrowth or regional osteomyelitis (Figure 6) The patient survived for 6 months after surgery with an improved quality of life and without any further health problems. Unfortunately, long-term follow-up was not possible owing to the death of the patient from predation by a wild animal.
Transverse (A) and sagittal (B) CT images of the fish of Figure 1 five weeks after removal of a benign lipoma from the left body wall just ventral and lateral to the dorsal fin. Notice that the fat-attenuating mass present in the CT images of Figure 2 is absent. There is focal disruption of fascial planes and a shallow cutaneous defect (arrowheads) where the mass was removed.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Transverse (A) and sagittal (B) CT images of the fish of Figure 1 five weeks after removal of a benign lipoma from the left body wall just ventral and lateral to the dorsal fin. Notice that the fat-attenuating mass present in the CT images of Figure 2 is absent. There is focal disruption of fascial planes and a shallow cutaneous defect (arrowheads) where the mass was removed.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Transverse (A) and sagittal (B) CT images of the fish of Figure 1 five weeks after removal of a benign lipoma from the left body wall just ventral and lateral to the dorsal fin. Notice that the fat-attenuating mass present in the CT images of Figure 2 is absent. There is focal disruption of fascial planes and a shallow cutaneous defect (arrowheads) where the mass was removed.
Citation: Journal of the American Veterinary Medical Association 256, 12; 10.2460/javma.256.12.1379
Discussion
Cutaneous neoplasms are the most commonly reported neoplasm of fish and are typically benign.22 In teleosts, lipomas (tumors arising from adipose tissue) typically occur as dermal or hypodermal tumors that may develop cutaneous ulceration,23 as was observed for the patient of the present report. Lipomas have been reported to develop internally in the hepatic parenchyma and coelomic membranes of fish.24–26 In some fish, dermis-associated lipomas have been found to infiltrate the underlying muscle.27 For the patient of this report, although well-differentiated adipocytes did dissect layers of skeletal myocytes in a very small section of the mass, the majority of the lipoma caused only compressive atrophy of the surrounding musculature. Adipose-associated neoplasms in teleosts can have more aggressive characteristics than those described for the mass in this report and may be histologically diagnosed as liposarcomas or invasive lipomatosis.28–30,l,m The mass removed from the fish of this report was diagnosed as a benign lipoma on the basis of sheets of well-differentiated adipocytes, minimal anisokaryosis and anisocytosis, and the absence of mitotic figures.
Lipomas have been reported in several fish orders such as Cypriniformes (bream), Perciformes (large-mouth bass, black crappie, striped seabream, and European seabass), Scombriformes (southern bluefin tuna and northern bluefin tuna), Siluriformes (channel catfish), Anguilliformes (European eel), Mugiliformes (striped mullet), Pleuronectiformes (common dab), and Cyprinodontiformes (molly).29 The underlying etiology of lipoma development in fish is unknown, but several theories have been proposed, including bony dysraphism when the lipoma develops close to bone and near the skull or vertebral column,31,32 endocrine or neurologic disorders, errors in fat metabolism,33 and exposure to chemicals, such as N-methyl-N'-nitro-N-nitrosoguanidine.34 For the fish of this report, like most others, the underlying etiology of the lipoma was unknown. Given that the lipoma was located in close proximity to the dorsal vertebral processes, it is plausible that a bony dysraphism may have been the underlying cause.
To our knowledge, the present report was the first to describe the use of advanced diagnostic imaging to make an antemortem diagnosis with subsequent successful surgical removal of a lipoma in a teleost. This report highlighted the challenges regarding transport, advanced imaging, surgery, and postoperative follow-up for a fish. Despite those challenges, the fish of this report was successfully treated. This case served as evidence that such medical endeavors can be performed on fish and lead to a positive outcome for patients and owners.
The relationship between the university teaching hospital and a local koi wholesaler facility was critically important for the management of the fish of the present report because it allowed the patient to appropriately reacclimate after 6 hours of transport by plane and van. It also facilitated the transport of the patient to and from the teaching hospital for diagnostic testing, surgery, and postoperative monitoring. Without that relationship, we would not have been able to reevaluate and acquire postoperative CT images of the patient without great expense to the owner and additional stress on the patient from subsequent long-distance transports.
Anesthesia and surgery of fish are associated with many unique obstacles. The inherent differences between fish and terrestrial animals dictate the use of a special approach to anesthesia, which usually involves submersion and bathing of the patient in water containing anesthetics, such as eugenol or tricaine methanesulfonate (MS-222).16 Injectable anesthetics have been used in fish, but an in-depth discussion of that topic is beyond the scope of this paper. Nevertheless, because most surgeries on fish need to be performed with the patient out of water to maintain asepsis and facilitate visibility and accessibility of tissues during the procedures, a method for bathing the gills with anesthetic-containing water is necessary. That method generally involves a recirculating water system to continuously pump anesthetic-containing water through the mouth and over the gills,16 as was described for the physical examination, ultrasound-guided biopsy, surgical procedure, and reevaluation of the patient of the present report. The recirculating water system used for the patient of this report was custom made at the teaching hospital with commercially available pumps, silicone tubing, and 2 glass terrariums that contained different concentrations of anesthetic solution, so anesthetic depth could be adjusted as needed.
The anesthetic technique had to be substantially modified for the acquisition of CT images to account for the inherent limitations associated with the use of a high-cost water-sensitive CT machine. The custom-made water recirculation system was too large for the gantry of the CT machine and could not be adapted to move with table advancement. Moreover, the continuous flow of water could have caused serious damage to the electronics of the CT machine. Because of the time required to acquire both precontrast and postcontrast CT images, we chose to bathe the gills of the patient every 15 to 20 seconds with oxygenated, anesthetic-containing water by use of 60-mL syringes. The water was injected into the mouth and directly behind both opercula. That method allowed the anesthetic depth to be easily and manually adjusted as needed throughout the procedure. The patient recovered from anesthesia rapidly and without any apparent complications, which suggested that the method used may be an acceptable alternative for maintaining fish at an appropriate anesthetic depth when a recirculating water system is unavailable or otherwise logistically prohibitive.
General surgical techniques and practices performed on terrestrial animals can and should be applied to fish without sacrificing asepsis, atraumatic tissue handling, hemostasis, analgesia, or perioperative antimicrobial use. More detailed discussions on surgical preparation, patient positioning, closure techniques, and recommended surgical instruments for use in fish were beyond the scope of the present report and can be found elsewhere. Surgical removal of the lipoma allowed the patient of the present report to return to normal behavior and improved its quality of life, which were the primary reasons the owner elected to pursue the diagnostic workup and surgical intervention.
The successful outcome for the patient of the present report was dependent on several factors unrelated to the veterinary care provided. The owner was willing to make the financial commitment necessary to transport and treat the patient. The relationship between the university teaching hospital and the local koi wholesaler facility, which facilitated transport and provided acclimation and postoperative care for the patient, was critical. The unique logistic issues associated with treating fish can be difficult to overcome unless the owner is able and willing to make the necessary financial commitment and the veterinary institution has the ability to hospitalize fish patients for an extended period of time or has a relationship with a local facility that is able to assist with the transport and housing of such patients. The present report suggested that with creativity and an open mind, practitioners can work within the inherent constraints, overcome obstacles, and provide high-level medical care to fish and aquatic patients.
Acknowledgments
No third-party funding or support was received in connection with this study or the writing or publication of the manuscript. The authors declare that there were no conflicts of interest.
The authors thank Vicki Vaughn and Carl Foss of The Koi Store, Watkinsville, Ga, for assistance with fish transportation and boarding between procedures.
Footnotes
Nijikawa premium koi food, EWOS, City of Industry, Calif.
The Koi Store, Watkinsville, Ga.
AQUI-S 20E (10% eugenol solution), AquaTactics Fish Health, Kirkland, Wash.
Siemens Somatom Sensation 64 CT scanner, Erlangen, Germany.
Omnipaque injection, GE Healthcare Inc, Princeton, NJ.
Logiq S8 ultrasound, GE Healthcare Inc, Princeton, NJ.
Tru-Cut 14-gauge biopsy needle, Medline Industries Inc, Mundelein, Ill.
Cefazolin, WG Critical Care LLC, Paramus, NJ.
Torbugesic, Zoetis Inc, Kalamazoo, Mich.
4.0 MHz Surgitron, Ellman International Inc, Hicksville, NY.
Monocryl-Plus Antibacterial Suture, Ethicon US LLC, Blue Ash, Ohio.
Bambir S, Helgason S, Marino F, et al. Some interesting tumours in fish (abstr), in Proceedings. 11th Annu Ljudevit Jurak Int Symp Comp Pathol 2000;33.
Volpatti D, Patarnello P, Novelli A, et al. Lipoma, fibrolipoma, liposarcoma in mormore, Lithognatus mormyrus (L) alleviate (abstr), in Proceedings. Histol Ultrastruct Observ Conf Societa Italiana Pathologia Ittica (SIPI) 1998.
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