Veterinary involvement with fish continues to advance because of needs for high-quality individual animal care, population-based aquarium medicine, commercial aquaculture, and research.1,2 The growing number of valuable display fish being kept by private individuals has resulted in many practitioners becoming interested in fish medicine. Presently, fish medicine relies heavily on evaluation of water quality, external diagnostic tests (skin, gill, and fin sampling), and necropsy examinations for disease diagnosis.2 Although internal-imaging procedures, including radiography and ultrasonography, are routinely used and can be used to facilitate fine-needle aspiration for cytologic examination, they do not permit the collection of tissue biopsy specimens, which are generally preferred for the histologic diagnosis of internal disease.1–3 Although elective necropsy is undoubtedly preferred for disease diagnosis in group situations, it is unacceptable when dealing with valuable display fish. Consequently, the antemortem collection of internal tissue biopsy specimens is preferred, and 2 options are coeliotomy and coelioscopy.
Ventral midline coeliotomy has been advocated for many species of fish for exploration of the body cavity, corrective surgery, and tissue sampling.3–5 However, such techniques require substantial incisions to permit viewing and manipulation of tissue and are complicated by post-operative wound dehiscence, infection, and evisceration, especially when intensive postoperative care and antimicrobial treatment cannot be adequately provided. Laparoscopy has major benefits over traditional laparotomy in humans and other animals.5–15 Rigid endoscopy has been used for diagnostic purposes in fish for many years and more recently for performing endosurgery.3–5 Human laparoscopy has been credited with more rapid and accurate diagnosis, reduced need for extensive laparotomy, reduced surgical stress, reduced pain and discomfort, improved postoperative pulmonary function, reduced hypoxemia, reduced surgery times, and faster recoveries.7–11 However, there have been no controlled studies to assess the benefits, if any, of coelioscopy over coeliotomy in any piscine species. Therefore, the aim of the study reported here was to evaluate endoscopic and surgical visceral examination and biopsy by use of liver biopsy of channel catfish (Ictalurus punctatus) as a laboratory model.
Materials and Methods
Animals—Thirty farmed channel catfish were maintained at the Fishery Research Center, University of Georgia. All fish were reproductively inactive subadults between 2 and 3 years of age. Methods and procedures were reviewed and approved by the University of Georgia's Institutional Animal Care and Use Committee (AUP #A2006-10216-0). Fish were weighed (Table 1) and permitted to acclimatize for 2 weeks before being randomly assigned to control, coeliotomy, and coelioscopy groups, each in a separate tank. During the acclimatization period, the temperature, pH, dissolved oxygen, and ammonium concentrations were monitored on a daily basis (Table 2). The fish were monitored 2 to 3 times daily and were fed a commercial diet twice daily. The same open-flow bio-filtering system was used for all 3 tanks, with water temperature maintained at 28°C (82°F). The day before surgical procedures were performed, each fish was anesthetized in a 57-L (15-gallon) tank containing maintenance tank water and tricaine methane sulphonatea (175 mg/L) buffered with sodium bicarbonate (350 mg/L) to maintain a pH of 6.5 to 7.2. Once fish were immobilized, an accurate body weight and total body length were obtained before each fish was individually identified by means of fin clipping. Fish were permitted to recover in a 190-L (50-gallon) tank containing fresh aerated water before being returned to their respective holding tanks.
Weight (mean ± SD [range]) of catfish during an acclimatization period, before surgery, 24 hours after surgery, and 14 days after surgery at necropsy for control, coeliotomy, and coelioscopy groups.
| Variable | Control group (n = 10) | Coeliotomy group (n = 10) | Coelioscopy group (n = 10) |
|---|---|---|---|
| Weight (g) at start of acclimatization period | 405.6 ± 65.0 (316 7−519 8) | 636.5 ± 251.9 (362 7−1180 0) | 572.5 ± 202.6 (394 4−895 3) |
| Weight (g) before surgery | 391.0 ± 66.0 (310.8−505.8) | 636.5 ± 250.0 (362.7−1180.0) | 570.3 ± 262.2 (372.0−1064.7) |
| Weight (g) 24 hours after surgery | 384.4 ± 60.8 (301.0−487.8) | 608.7 ± 234.2 (344.4−1101.1) | 575.3 ± 261.2 (377.0−1065.0) |
| Weight (g) 14 days after surgery at necropsy | 453.0 ± 140.7 (331.1−569.0) | 446.5 ± 298.0 (367.7−1213.3) | 547.6 ± 243.2 (370.0−1064.2) |
| Mean weight gain (+) or loss (−) during study | +47.4 g +11.7% | −190.0 g −29.8 % | −24.9 g −4.3 % |
Mean husbandry data for catfish in control, coeliotomy, and coelioscopy groups.
| Treatment group | 14—day period | Temperature (°C)* | pH | Dissolved oxygen (mg/L) | Total ammonia nitrogen (ppm) | Nonionized ammonia (mg/L) |
|---|---|---|---|---|---|---|
| Control (n = 10) | Acclimatization | 28.6 | 7.4 | 6.9 | 0.5 | 0.009 |
| Postanesthesia | 29.3 | 7.1 | 6.3 | 0.6 | 0.006 | |
| Coeliotomy (n = 10) | Acclimatization | 28.6 | 7.4 | 7.0 | 0.4 | 0.007 |
| Postoperative | 29.2 | 7.2 | 6.7 | 0.6 | 0.007 | |
| Coelioscopy (n = 10) | Acclimatization | 28.7 | 7.4 | 7.0 | 0.4 | 0.007 |
| Postoperative | 29.4 | 7.3 | 6.4 | 0.6 | 0.009 |
To convert values to degrees Fahrenheit, multiply the value by 9/5 and add 32.
Published and accepted normal water variables16,17: temperature, 22° to 32°C with optimal growth at 29°C; pH, 6.5 to 7.5; dissolved oxygen > 5 mg/L; total ammonia nitrogen < 2 ppm; nonionized ammonia < 0.02 mg/L.
Anesthesia—All fish undergoing anesthesia did not receive food for 24 hours before the anesthetic episode. The anesthetic regimen was the same for all fish. Once anesthesia was induced by use of the described technique, each fish was moved to a water-recirculating anesthesia machine.1,4 This consisted of a 10-gallon glass tank containing 2 gallons of freshly prepared anesthetic maintenance water (tricaine methane sulphonate [125 mg/L], and sodium bicarbonate [250 mg/L]). A small submersible pumpb forced water through a rubber tube up to a plexiglass platform positioned on top of the tank (Figure 1). Each fish was positioned in dorsal recumbency by use of a modified V-slot plexiglass platform, and the rubber tube was positioned inside the buccal cavity to facilitate water flow over both sets of gills. Water flowing out of the opercula dripped back into the aquarium and was recirculated. Anesthetic monitoring included a visual appraisal of spontaneous movement and tail pinch reflexes, evaluation of heart rate with an ultrasonic Doppler flow detector,c and use of a pulse oximeter placed across the commissure of the mouth.d
Photograph of a fish anesthesia machine. A small submersible pump is placed in the reservoir and used to pump water through a rubber tube up to a plexiglass platform positioned on top of the tank to maintain anesthesia for the fish (a). Catfish are positioned in dorsal recumbency by use of a modified V-slot plexiglass platform (b). A rubber tube is positioned inside the mouth to ensure water flow over both sets of gills.
Citation: Journal of the American Veterinary Medical Association 233, 6; 10.2460/javma.233.6.960
Blood samples and analysis—With the fish in dorsal recumbency, 0.5 mL of blood was collected from the caudal vein with a 3-mL syringe and 22-gauge needle and used to fill 2 heparinized Hct tubes with 0.4 mL placed into a lithium heparin plasma separator tube. Microhematocrit and blood tubes were immediately centrifuged at 5,000 × g for 5 minutes. Packed cell volume percentage and refractometric TP concentration were measured from both Hct tubes, and the mean values recorded. Plasma was harvested from the plasma separator tube and stored in Eppendorf tubes at −80°C until batch processed. The following plasma muscle and liver enzymatic activities were measured: AST,e CK,e LDH,e and SDH.f Biochemical analyses were performed on an automated analyzerg at 30°C by use of kinetic assays. Paired (pre- and postoperative) plasma samples were thawed and batch processed at the same time.
Surgery—Ten fish were subjected to a standard coeliotomy and liver biopsy (coeliotomy group).3–5 A sterile cotton swab soaked with sterile saline (0.9% NaCl) solution was swiped once along the intended surgical incision site to remove mucus; however, in keeping with published protocols, extensive use of an antiseptic for presurgical preparation was not used.3 All surgical instruments were cold sterilized in a 2% glutaraldehydeh solution for 20 minutes and rinsed with sterile water before each surgery. With a No. 15 surgical blade, the surgeon made an 8- to 10-cm ventral midline incision through skin and the hypaxialis and infracarinalis muscles, starting just caudal to the pectoral fins and ending midway to the anus. Following a brief evaluation of visible viscera, including the stomach, liver, gallbladder, small intestine, and spleen (Figure 2), a liver biopsy specimen was collected either from the left or right liver lobe with a standard suture loop technique and 3-0 polydioaxanone suture.18 Liver tissue was placed into neutral-buffered 10% formalin and submitted for routine histologic examination. The body wall was closed as a single layer with 3-0 polydioaxanone suture in a simple interrupted pattern (Figure 3).
Photograph of coeliotomy and liver biopsy in a catfish. Ventral coeliotomy illustrates the limited exposure of the coelom (a). The suture loop technique (b) is used to harvest liver tissue.
Citation: Journal of the American Veterinary Medical Association 233, 6; 10.2460/javma.233.6.960
Photograph of results of surgical closure for coeliotomy (a) and coelioscopy (b).
Citation: Journal of the American Veterinary Medical Association 233, 6; 10.2460/javma.233.6.960
Ten fish were subjected to coelioscopic visceral examination and liver biopsy (coelioscopy group). A sterile cotton swab soaked with an antiseptic was swiped once along the intended surgical incision site to remove mucus.3 All surgical instruments were cold sterilized in a 2% glutaraldehyde solution for 20 minutes and rinsed with sterile water before each surgery. With a No. 15 surgical blade, the surgeon made a 4-mm skin incision in the ventral midline, halfway between the pectoral fins and the anus. A 2.7-mm × 18-cm 30° rigid endoscopei housed within a 4.8-mm (14.5-F) operating sheathj was inserted into the coelom and connected to a 175-W xenon light source via a fiber-optic light guide cable, endovideo camera, and monitork (Figure 4). A 1.0-L bag of sterile saline solution was connected through a sterile IV line to one of the ports on the operating sheath. Saline solution was infused into the coelom to create a working space, and an evaluation of visible viscera, including the stomach, liver, gallbladder, cranial and caudal kidneys, gonads, small and large intestine, spleen, swim bladder, and urinary bladder, was performed. Two liver biopsy specimens were collected with 1.7-mm (5-F) biopsy forcepsl inserted into the coelom via the instrument channel of the operating sheath. Following biopsy, the sheathed endoscope was removed, saline solution was gently expressed from the coelom, and the entry site was closed by use of a single, simple interrupted 3-0 polydioaxanone suture (Figure 3).
Photographs of coelioscopy in a channel catfish performed with a 2.7-mm telescope and saline (0.9% NaCl) solution insufflation (a), endoscopic view of the right liver lobe (b), endoscopic view of liver biopsy performed with 5-F biopsy forceps (c), and endoscopic view of the biopsy site (d).
Citation: Journal of the American Veterinary Medical Association 233, 6; 10.2460/javma.233.6.960
Ten fish were not subjected to any surgical procedure (control group) but were anesthetized for blood collection and maintained under anesthesia for 10 minutes (approximate duration of surgery). All fish in the coeliotomy and coelioscopy groups received 0.2 mg of meloxicamm/kg by IM injection before recovery from anesthesia.
Postoperative monitoring—Immediately after surgery, the fish were placed into a recovery tank, where they were monitored until they were able to swim on their own, at which time they were placed back into their respective holding tanks and monitored daily for food intake and any evidence of illness. Food was withheld for 24 hours after surgery because of the need to reanesthetize the fish the next day. Twenty-four hours following the surgical procedures, all fish were again anesthetized and weighed, and blood was collected as described. Any fish that died was subjected to a gross necropsy examination, and abnormal tissues were submitted for histologic examination. For the 14 days following the procedures, the temperature, pH, dissolved oxygen, and ammonium concentrations were monitored on a daily basis (Table 2). The catfish were monitored 2 to 3 times daily and were fed a commercial diet twice daily.
Necropsy and histologic examination—On day 14, all remaining fish were euthanatized in a solution of MS222 (450 mg/L) and sodium bicarbonate (900 mg/L). A gross necropsy examination, including accurate weight (Table 1), was performed on each fish, and tissue samples were submitted for histologic examination. Particular care was taken to assess fish for wound dehiscence, trauma, or infection that might have been attributable to the surgical procedures. Submitted biopsy specimens and necropsy tissues, including hepatopancreas, cranial and caudal kidney, stomach, intestine, spleen, liver, gonad, heart, and body wall, were routinely processed, sectioned at 5 μm, stained with H&E, examined microscopically, and objectively assessed and scored for various features, including the extent of melanomacrophage aggregates, mononuclear cellular infiltrates, crush artifact, and necrosis. These findings were individually scored as 0 (not present), minimal (1+), mild (2+), moderate (3+), or severe (4+). The overall diagnostic quality of the specimens was scored numerically as poor (1), moderate (2), or good (3).
Statistic analysis—Statistical evaluations were performed with dedicated computer software.n Percentage changes between pre- and postsurgical values were calculated for body weight, PCV, TP, AST, CK, LDH, and SDH. Means for measured values and percentage changes were compared by use of ANOVA when all 3 treatments were compared or by use of a Student t test when only paired data were reported. When significant differences were found with ANOVA, multiple comparisons were made by use of the Tukey test. Preversus postsurgical values for pathology variables were compared for each treatment (coelioscopy and coeliotomy) separately by use of paired t tests. For all comparisons, P < 0.05 was considered significant.
Results
Fish handling, blood sampling, fin marking, anesthesia, and surgical procedures were all completed and well tolerated without occurrence of deaths. Anesthesia and surgery times were recorded (Table 3). Stomach, spleen, small and large intestine, swim bladder, liver, and gall bladder could be visualized via coeliotomy and coelioscopy techniques. However, cranial and caudal kidney, inactive gonads and reproductive tract, terminal portion of the large intestine, and caudal fat body could only be reliably visualized by use of endoscopy. Biopsy procedures were successfully performed in all cases, without notable hemorrhage.
Anesthesia induction, surgery, and recovery times for catfish undergoing anesthesia, coeliotomy, and coelioscopy procedures.
| Treatment group | Induction time (min) | Surgery time (min) | Recovery time (min) |
|---|---|---|---|
| Control (n = 10) | 3.9 ± 0.9 | 10.0 ± 0.0 | 1.9 ± 0.7 |
| Coeliotomy (n = 10) | 3.0 ± 0.9 | 9.9 ± 1.0 | 2.1 ± 0.7 |
| Coelioscopy (n = 10) | 3.3 ± 0.4 | 8.9 ± 1.8 | 2.0 ± 0.5 |
The PCV and TP were significantly lower following coelioscopy (32.9 ± 7.2% and 5.6 ± 0.6 mg/dL, respectively [Table 4]) than following coeliotomy (25.6 ± 3.9% and 4.6 ± 1.2 mg/dL, respectively; P < 0.05). No significant differences were detected between the coeliotomy and coelioscopy groups for the LDH, AST, SDH, and CK values.
Plasma biochemical results for catfish undergoing anesthesia (n = 10), coeliotomy (10), and coelioscopy (10) procedures.
| Treatment group | PCV(%) | TP(g/dL) | AST(U/L) | LDH(U/L) | SDH(U/L) | CK(U/L) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean ± SD | Range | Mean ± SD | Range | Mean ± SD | Range | Mean ± SD | Range | Mean ± SD | Range | Mean ± SD | Range | |
| Control: (preanesthesia) Control: | 34.8 ± 0.9 | 34−37 | 6.1 ± 0.9 | 5.0−7.5 | 69 ± 53 | 26−204 | 141 ± 208 | 20−671 | 2.6 ± 1.1 | 0.5−4.1 | 3,844 ± 4,174 | 510−12,948 |
| (postanesthesia) | 34.7 ± 2.2 | 29−37 | 6.3 ± 0.5 | 5.8−7.2 | 85 ± 73 | 35−265 | 103 ± 84 | 29−266 | 6.4 ± 11.3 | 0.5−38 | 4,463 ± 5,158 | 1,934−18,238 |
| Precoeliotomy | 28.4 ± 3.7 | 29−36 | 5.8 ± 1.2 | 4.2−7.0 | 136 ± 96 | 40−365 | 242 ± 196 | 63−674 | 4.2 ± 1.8 | 2.8−7.9 | 6,875 ± 10,862 | 755−36,156 |
| Postcoeliotomy | 25.6 ± 3.9 | 27−36 | 4.6 ± 1.2 | 4.0−7.0 | 137 ± 44 | 83−200 | 167 +74 | 86−309 | 4.7 ± 3.5 | 1.1−13.2 | 4,573+ 3,439 | 2,049−13,209 |
| Precoelioscopy | 35.2 ± 4.8 | 27−44 | 6.4 ± 0.6 | 5.0−7.4 | 119 ± 63 | 66−223 | 237 ± 315 | 37−1074 | 4.5 ± 2.3 | 1.8−8.2 | 3,043 ± 2,405 | 788−6,805 |
| Postcoelioscopy | 32.9 ± 7.2 | 30−52 | 5.6 ± 0.6 | 4.5−6.5 | 133 ± 160 | 10−576 | 206 ± 179 | 24−477 | 3.1 ± 1.8 | 1.4−7.3 | 7,712 ± 9,045 | 1,269−31,020 |
Coeliotomy and coelioscopy resulted in biopsy specimens of moderate to good diagnostic quality, and biopsy and necropsy histologic findings were summarized (Figure 5; Table 5). At necropsy, 3 of 10 coeliotomytreated fish had developed severe wound dehiscence, whereas all surgical sites in the coelioscopy group healed without incident (Figure 6). More extensive and severe histologic abnormalities were detected following coeliotomy, compared with control and coelioscopy groups. The pathologic changes observed in the control group included splenic lymphocellular depletion (n = 3), deep ulcerative epidermitis with intralesional bacteria (1), and myositis, microthrombosis, hemorrhage, and necrosis (2). Lesions in the coeliotomy group included generalized sepsis (n = 1); hepatocellular necrosis (2); nonheterophilic myocarditis with intralesional bacilli (2); myofiber degeneration and necrosis with intralesional bacteria in the body wall (2); lymphocytic cellulitis and edema of the body wall (1); and discrete necrosis of the anterior kidney, body fat, and ovary (1). Lesions in the coelioscopy group included septic myocarditis (n = 1), systemic sepsis (1), splenic necrosis (1), and lymphoplasmacytic inflammation of the body wall (1). Bacterial cultures were not performed.
Histologic scores (mean ± SD) for biopsy and necropsy liver samples for channel catfish (n = 10/treatment group).
| Treatment group | Melanomacrophages | Mononuclear cellular infiltration | Crush artifact | Necrosis | Diagnostic quality | |
|---|---|---|---|---|---|---|
| Control | Necropsy | 1.3 ± 0.5 | 0.0 ± 0.0 | 0.0 ± 0.0 | 0.0 ± 0.0 | 3.0 ± 0.0 |
| Coeliotomy | Biopsy | 1.0 ± 0.0 | 0.1 ± 0.3 | 1.0 ± 0.5 | 0.0 ± 0.0 | 3.0 ± 0.0 |
| Necropsy | 1.3 ± 0.5 | 0.1 ± 0.3 | 0.3 ± 0.4 | 1.0 ± 1.76 | 2.3 ± 1.0 | |
| Coelioscopy | Biopsy | 1.2 ± 0.8 | 0.0 ± 0.0 | 1.5 ± 0.6 | 0.0 ± 0.0 | 3.0 ± 0.0 |
| Necropsy | 1.1 ± 0.3 | 0.0 ± 0.0 | 0.3 ± 0.6 | 0.0 ± 0.0 | 2.0 ± 1.0 |
Findings were scored as 0 (not present), minimal (1+), mild (2+), moderate (3+), or severe (4+). The overall diagnostic quality of the specimens was scored as poor (1), moderate (2), or good (3).
Microscopic appearance of the hepatic parenchyma in a fish following surgical biopsy (a) and endoscopic biopsy (b). Both specimens are adequate for diagnostic purposes. H&E stain; bar = 25 μm.
Citation: Journal of the American Veterinary Medical Association 233, 6; 10.2460/javma.233.6.960
Gross view of sutured wounds 7 days after coeliotomy (a), 14 days after coeliotomy (b), and 14 days after coelioscopy (c). Bar = 1cm.
Citation: Journal of the American Veterinary Medical Association 233, 6; 10.2460/javma.233.6.960
Discussion
A comparison between the pre- and postoperative physical, clinicopathologic, and histologic data enabled an evaluation and comparison of coeliotomy and coelioscopy liver biopsy techniques. No significant differences were detected between coeliotomy and coelioscopy groups for anesthetic induction, surgery, or recovery times. The increased surgery time associated with suturing during coeliotomy was offset by the time taken to visualize more visceral tissues during coelioscopy.
Although the coeliotomy procedure provided good access to the cranial coelom, including the liver, stomach, spleen, and swim bladder, evaluation of the dorsal and caudal structures was hampered. Conversely, coelioscopy facilitated a more complete examination of the coelom, gonads, cranial and caudal kidney, caudal portion of the intestinal tract, and urinary bladder. Saline solution infusion induced mild distension of the coelom that aided visceral examination during coelioscopy. Saline solution infusion is preferred over CO2 insufflation because, unlike gas, residual saline solution does not cause postoperative buoyancy problems.
The PCV and TP were significantly lower following coelioscopy than coeliotomy despite lack of hemorrhage detected during surgery, after surgery, or postmortem. Decreases in PCV (−0.81 ± 0.04%) and TP (−0.82 ± 0.04%) values were attributed to mild hemodilution associated with residual saline solution left within the coelom following infusion and coelioscopy. No deleterious effects were associated with residual saline solution within the coelom or mild hemodilution. Indeed, intracoleomic saline solution may be expected to be advantageous by providing fluid therapy and flushing the coelom to reduce bacterial contamination.
Increased CK and LDH activities in the preoperative samples were possibly the result of handling and penetration of muscle during venipuncture of the caudal tail vein. Muscle cells are rich in CK activity and also have moderate LDH activity. Elevation of CK and LDH activities is expected after surgery because the body wall is penetrated during rigid endoscopy and traditional coeliotomy. The greatest increase, although not significant, in AST and SDH activities was apparent in the postceliotomy groups in which more manipulation of the body wall and liver occurred for exploration and sample collection. However, both the celiotomy and celioscopy groups could also have developed an increase in LDH and CK associated with the IM injection of meloxicam.
There were no significant differences in biopsy specimen score between coeliotomy and coelioscopy groups, and both resulted in biopsy specimens of diagnostic quality. Although crush artifact was greater in hepatic biopsy specimens obtained by use of endoscopy than by traditional removal of a wedge of tissue, both procedures provided samples of diagnostic quality. Results of previous studies19,20 indicate that samples obtained via a small needle biopsy should be interpreted with caution. The biopsy specimens obtained by use of coeliotomy were larger and allowed for more extensive assessment of the parenchyma. The endoscopic biopsy specimens, although of similar overall diagnostic quality, were smaller and had crush artifact more frequently.
Coeliotomy resulted in complete wound dehiscence in 3 of 10 fish, whereas all surgical sites healed without complication in the coelioscopy group. The smaller size of the surgical incision and decrease in visceral exposure are important advantages of coelioscopy that reduce postoperative complications. The use of antimicrobials after surgery may have helped prevent or reduce sepsis, but they were not used in this study to investigate the unaltered effects of surgery and endoscopy on the study fish.
Significant weight changes occurred during the study. The control group gained 12% of body weight, indicating appropriate captive management, whereas the coeliotomy and coelioscopy groups lost 30% and 4%, respectively. We suspect that surgical trauma was responsible for the weight loss in both surgery groups and that the coelioscopy group lost less weight because of less trauma, compared with coeliotomy.
Four fish in the coeliotomy group, 3 in the coelioscopy group, and 3 in the control group died in the holding tanks during the 14 days following the procedures. Being confined in holding tanks may have increased stress, thus causing minimal to mild splenic lymphocellular depletion. Cutaneous epidermal ulceration and myositis were seen in 1 fish in the control group. These lesions commonly result from fighting, trauma, or handling. Three fish in the coeliotomy group and 2 fish in the coelioscopy group developed sepsis shortly before death. The portal of entry of the bacteria may have been the gastrointestinal tract, the surgical site, or the environment. Although sepsis was detected histologically, the specific identity of the bacteria was not confirmed via bacteriologic culture. Surgically associated muscle damage was seen in 3 fish in the celiotomy group and may have served as a portal of infection, resulting in degradation of the suture material and surgical site. Coelioscopy-associated lymphoplasmacytic inflammation of the body wall in the 1 fish was mild, but was possibly related to surgery. In the coelioscopy group, 1 fish also had cutaneous ulcers distant from the surgical site and multifocal septic myocarditis that probably contributed to death.
It is not uncommon for aquaculture systems to use UV sterilization to reduce the number of pathogens in the water. In addition, most captive fish that undergo surgery are likely to receive antimicrobial treatment and may in addition receive additional water quality improvements (eg, water changes or addition of low concentrations of salt) to reduce postoperative sepsis. However, the aim of this study was to compare the effects of coeliotomy and coelioscopy, without masking or mitigating the potential for infection. Furthermore, when performing coelioscopic examinations in free-ranging fish, it is impossible to reduce bacterial loads in the water.
Results of the present study indicated that although both coeliotomy and coelioscopy are practical procedures in catfish, endoscopy provided a more complete and detailed examination because of the focal illumination and magnification afforded by the telescope. Although the application of endoscopy in fish is still in its infancy, coelioscopy offers a minimally invasive approach to the coelom with considerable reduction in the size of the required surgical incision. The availability of telescopes varying from 1 to 10 mm in diameter enables coelioscopy in a wide size range of fish. Nevertheless, there are several potential problems with regard to endoscopy in fish. Basic endoscopy equipment (including camera, light source, guide cable, monitor, telescope, and basic instruments) represents a major capital investment, and training and practice are required to become proficient at endoscopy techniques.
Many fish procedures are performed in the field, and the provision of electrical power may be problematic. It is also necessary to appreciate the conformation of the species in question and adopt a commonsense approach. For example, although the ventral approach is preferred for a catfish, a lateral approach would be more practical for a laterally compressed species such as a flounder or angelfish. It is also essential to have a detailed appreciation of the coelomic anatomy of the species involved, and species-specific anatomical differences will often dictate endoscopy techniques. For example, although the internal organs of a catfish are unobstructed and easily visualized, coelioscopy of koi carp is often hindered by multiple adhesions that make movement of the telescope more difficult.
Results of the present study suggested that both coelioscopy and coeliotomy are capable of yielding antemortem liver biopsy specimens of diagnostic quality in catfish. However, coelioscopy was faster (or permits a more complete examination of the coelom in the same time period), was less traumatic, and resulted in decreased wound dehiscence and postoperative sepsis. Coelioscopy is therefore recommended for visceral organ examination and biopsy in fish.
ABBREVIATIONS
| AST | Aspartate aminotransferase |
| CK | Creatinine phosphokinase |
| LDH | Lactate dehydrogenase |
| SDH | Sorbitol dehydrogenase |
| TP | Total protein |
Spectrum Chemical Manufacturing Corp, Gardena, Calif.
FountainPro WA90 submersible pump, Jeantech Inc, Ellsworth, Wis.
Model 811-B, Parks Medical Electronics Inc, Aloha, Ore.
Vet/Ox 4404, Heska Inc, Loveland, Colo.
Boehringer Mannheim Corp, Indianapolis, Ind.
Diagnostics Chemical Ltd (USA), Oxford, Conn.
Hitachi 912 analyzer, Boehringer Mannheim Corp, Indianapolis, Ind.
CIDEX, Advanced Sterilization Products, Irvine, Calif.
64018BSA, autoclavable Hopkins rigid telescope, 2.7-mm × 18-cm working length, 30°, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
67065C, operating sheath for 64018BSA telescope, 14.5-F outer diameter, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
69235106, veterinary video camera II, 9219-B Sony medical grade monitor, 201320-20 xenon light source, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
67161Z, flexible biopsy forceps, 5 F × 34 cm, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
Metacam (meloxicam), Boehringer Ingelheim Vetmedica Inc, St Joseph, Mo.
SAS, version 9.1, SAS Institute Inc, Cary, NC.
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