Swim bladder tumors in the wavy medaka (Oryzias latipes)

Swim bladder tumors were detected in three out of 28 wavy medakas aged about 2 years old, all of which displayed abnormal swimming patterns caused by their spinal curvature. The tumors were located in the dorsal abdominal cavity. The swim bladder lumen was not detected in the region where it was originally assumed to be located, and that region was replaced with adipose tissue. The tumors were non-invasive, expansile, and encapsulated solid masses composed of a homogenous population of well-differentiated, densely packed, gas glandular epithelium-like cells. The tumor masses were connected to the rete mirabile, but the tumor cells did not infiltrate into them. Histopathologically, these tumors were diagnosed as adenomas originating from the gas glandular epithelium of the swim bladder. Spontaneous swim bladder tumors are rare in medaka, with an incidence of 0.02%; however, in the present study of wavy medaka, the incidence was much higher (10.7%). The long-term physical effects on the gas gland caused by swim bladder deformation considered to be a secondary effect of the spinal curvature may be an important factor in the proliferation of the gas glandular epithelium in the wavy medaka, resulting in the higher incidence of swim bladder tumors.     

Use of pneumocystoplasty for overinflation of the swim bladder in a goldfish

A Ryukin goldfish was evaluated because of a 6-month history of progressive abdominal distention and positive buoyancy. Overinflation of the swim bladder was diagnosed, and the fish was anesthetized with tricaine methanesulfonate. Archimedes' principle was used to determine the volume of swim bladder that was removed surgically. The caudal swim bladder was exteriorized through an abdominal incision and 2 surgical clips were placed across it to limit its size. After surgery, the fish remained in a state of negative buoyancy in sternal and lateral recumbency on the bottom of the tank. Sutures were removed 15 days after surgery, but the fish died 24 days after surgery. A full necropsy could not be performed because of autolysis of the tissues, but the surgical clips and the swim bladder appeared unremarkable. Pneumocystoplasty may be a viable treatment for this condition.     

Swim bladder tumor in the young adult scoliotic medaka (Oryzias latipes)

A swim bladder tumor was detected in one scoliotic medaka aged 22 weeks. The tumor was located in the dorsal abdominal cavity, with maximum dimension of 1,850 × 1,500 µm. No swim bladder lumen was identified, and the region where the swim bladder lumen would have been located, was replaced with adipose tissues. The tumor was a non-invasive, expansile, and encapsulated solid mass with a few cysts, and comprised a homogenous population of well-differentiated, densely packed, gas glandular epithelium-like cells. The tumor mass was connected to a rete mirabile that showed a hyperplastic capillary plexus; however, the tumor cells did not invade the rete mirabile, thereby revealing that the tumor was an adenoma originating from the gas glandular epithelium of the swim bladder. Since proliferative lesions in the swim bladder have been reported in some teleosts with skeletal deformations, including medaka, the occurrence of a spontaneous swim bladder tumor in teleosts is considered to be closely associated with various types of skeletal deformation, and spinal curvature in particular.     

THE USE OF COMPUTED TOMOGRAPHY FOR ASSESSMENT OF THE SWIM BLADDER IN KOI CARP (CYPRINUS CARPIO)

Seven normal koi (Cyprinus carpio) and seven koi with negative buoyancy were examined using computed tomography (CT) to assess the swim bladder. The volume of the swim bladder was calculated in all animals. In the healthy koi there was a statistical correlation (r=0.996) between body mass and swim bladder volume with volume (ml) being related to body mass according to the formula 4.9+0.054 × BM (g). In all koi with buoyancy problems, the gas volume of the swim bladder was reduced. Additionally, fluid was found within the swim bladder in three of the abnormal koi. CT proved to be a quick noninvasive technique for the examination of the swim bladder in koi.     

PET FISH RADIOGRAPHY: TECHNIQUE AND CASE HISTORY REPORTS

Radiography can be used to aid in the diagnosis and treatment of pet fish diseases. Handling, restraint and radiographic technique for the radiographic examination of pet fish is described. Quality diagnostic images can be obtained with standard radiographic equipment and radiographic techniques. Fishes with undifferentiated sarcoma, swim bladder herniation and scoliosis are three clinical examples that are described where radiography was used in the management of the patient. Conventional radiography appears to be best for evaluating skeletal and swim bladder diseases. Alternate imaging techniques such as computed tomography and magnetic resonance imaging may enhance the evaluation of coelomic soft tissue structures.     

Ontogeny of the stomach in yellow catfish (Pelteobagrus fulvidraco): detection and quantifictation of pepsinogen and H+/K+‐ATPase gene expression

Yellow catfish (Pelteobagrus fulvidraco) is an important commercial species with high aquaculture potential in China. To better understand the process of digestive functioning of gastric gland development during the larval from 1 dph (day post‐hatching) to 30 dph, real‐time PCR was used to detect and quantify the pepsinogen and H⁺/K⁺‐ATPase gene expression in P. fulvidraco. These data were also compared with the adult situation. The results showed that the expression of pepsinogen and H⁺/K⁺‐ATPase genes in P. fulvidraco larvae both started at 1 dph, though the expression level was very low until 3 dph. The quantification of pepsinogen gene expression increased significantly from 4 to 8 dph, increased fluctuantly from 8 to 23 dph and rose sharply from 23 to 30 dph. In comparison with adult fish, there were no significant differences with larvae at 5 and 23 dph. However, data of 10 and 30 dph larvae were obviously higher than those of adult group. H⁺/K⁺‐ATPase gene expression increased linearly from 1 to 30 dph. However, it was significantly lower than that of adult. The results show that P. fulvidraco larvae have an earlier functional stomach, though the function of the stomach is still not perfect. There is a gradual acidification environment within the stomach during the P. fulvidraco larvae development. Based on these results, we suggest that the weaning time for P. fulvidraco larvae would be much better after 23 dph.     

Survival of Largemouth Bass Iridovirus in Frozen Fish

Abstract

Juvenile largemouth bass Micropterus salmoides were infected with largemouth bass iridovirus by injection and frozen at ?10°C, and the visceral organs and tissues (liver, kidney, spleen, gonads, swim bladder, and muscle) of individual fish were periodically assayed for virus for 155 d postfreezing. The virus was isolated from 35 of 39 (89.7%) of the frozen fish. However, virus loss occurred more rapidly in fish that were dead when frozen than in fish that were alive when frozen. Overall, largemouth bass iridovirus was stable in frozen tissue when the fish were fresh upon freezing.     

Urologic disorders of the geriatric dog

Disorders of the urinary system are common in geriatric dogs. Common urinary disorders that are seen in older dogs include chronic renal failure, urinary incontinence, bladder tumors, and prostate problems. Therapy for chronic renal failure is aimed at both slowing the progression of the disease and ameliorating the signs of uremia. Therapeutic recommendations for the conservative medical management of chronic renal failure include reducing dietary protein, moderately reducing salt intake, maintaining normal serum phosphorus levels, providing free access to water, avoiding stress, supplementing water soluble vitamins, using anabolic steroids to treat the anemia of chronic renal failure, treating acidosis, and controlling hypocalcemia. Urinary incontinence can often be controlled or eliminated. The appropriate approach to management of this disorder is to identify and remove specific causes. Common causes of urinary incontinence are urethral incompetence, urinary tract infection, and polyuria and polydypsia. Bladder tumors are, fortunately, not a common tumor of dogs, but are more common in geriatric dogs than in the young. The most common bladder tumor is the transitional cell carcinoma. Therapy for this tumor is usually palliative because of its malignant nature and because it is usually located in the neck of the bladder. Its location in the bladder often makes it impossible to resect the tumor completely without removing the entire bladder and diverting the ureters. New chemotherapeutic modalities are being evaluated that may increase life expectancy after diagnosis and, therefore, improve prognosis. Prostate disease is also seen in older dogs. Types of prostate abnormalities seen in dogs include prostatic hyperplasia, cysts, abscesses, acute and chronic infection, and neoplasia. The institution of proper therapy requires an accurate diagnosis; neutering is often recommended as a part of therapy regardless of the type of prostatic disease present.     

Laparoscopic cholecystectomy under field conditions in Asiatic black bears (Ursus thibetanus) rescued from illegal bile farming in Vietnam

Nine adult Asiatic black bears (Ursus thibetanus) previously rescued from illegal bile farming in Vietnam were examined via abdominal ultrasound and exploratory laparoscopy for liver and gall bladder pathology. Three bears demonstrated notable gall bladder pathology, and minimally invasive cholecystectomies were performed using an open laparoscopic access approach, standard 10 to 12 mmHg carbon dioxide pneumoperitoneum and a four-port technique. A single bear required insertion of an additional 5 mm port and use of a flexible liver retractor due to the presence of extensive adhesions between the gall bladder and quadrate and left and right medial liver lobes. The cystic duct was dissected free and this and the cystic artery were ligated by means of extracorporeal tied Meltzer knot sutures. The gall bladder was dissected free of the liver by blunt and sharp dissection, aided by 3.8 MHz monopolar radiosurgery. Bears that have had open abdominal cholecystectomies are reported as taking four to six weeks before a return to normal activity postoperatively. In contrast, these bears demonstrated rapid unremarkable healing, and were allowed unrestricted access to outside enclosures to climb trees, swim and interact normally with other bears within seven days of surgery.     

Aeromonas hydrophila Isolated from Wild Freshwater Fish in Croatia

Aeromonas hydrophila was recovered from fish living in lake Vrana on the Croatian island of Cres. The occurrence of the bacterium in the fish was assessed and related to gross signs of disease and findings at necropsy as a potential health hazard for fish. Isolated bacteria were subjected to morphological, physiological, biochemical and antibiotic susceptibility tests. A total of 26 A. hydrophila isolates were obtained. There was a clear seasonality, as no isolates were recovered in the summer months. Most of the isolates were sensitive to all the antimicrobials used in the study except novobiocin and penicillin G. Affected fish manifested haemorrhages over the skin, in the liver, kidney and swim bladder, spleen infarcts, fatty liver, ascitic fluid and swollen haemopoietic tissues. A. hydrophila does not appear to pose a major threat for the fish in the lake at present but under unfavourable and stressful conditions it could seriously compromise fish health.     

Surgery in fish.

Surgery in fish is feasible and practical for clinical and research applications. Certain adjustments in standard surgical procedures are necessary to accommodate piscine tissue handling, skin sensitivity, aqueous respiration, anatomic variations, and patient size. General considerations for fish surgery, including anesthesia, presurgical evaluation, equipment, suture selection, and surgical site preparation, have been presented here. Procedures described include celiotomy, enucleation, pseudobranchectomy, swim bladder surgery, gonadectomy, liver and kidney biopsy techniques, telemetry device implantation, and vascular catheterization.     

Surgical removal of a seminoma from a black sea bass

An adult black sea bass was examined because of abdominal distention and decreased appetite. A large abdominal swelling was evident and was firm on palpation. Differential diagnoses included neoplasia, abscess or granuloma, hematoma, or swim bladder abnormality. Diagnostic tests included survey radiography, positive-contrast radiography, and computed tomography. The sea bass was anesthetized with tricaine methanesulfonate. A ventral midline abdominal incision was made, and adhesions to the mass were gently dissected. The fish recovered without complications. Radiography was repeated 8 weeks after surgery, and there was no evidence of mass regrowth. To the authors' knowledge, this is the first report of a barium enema being performed in a fish. Although surgical procedures are performed more commonly on fish for research, a few reports of clinical surgical cases have been described. Our experience supports the conclusions of other reports that certain surgical procedures can be performed safely in fish.     

Improvement in In Vitro Fertilization Rate,Decrease in Reactive Oxygen Species and Spermatozoa Death Incidence in Rams by Dietary Fish Oil

Our aim was to evaluate the effects of fish oil feeding on sperm classical parameters, level of reactive oxygen spices (ROS), spermatozoa death incidence and in vitro fertilization (IVF) rate in rams. We randomly assigned nine rams, into two experimental groups (isoenergetic and isonitrogenous rations with constant level of vitamin E supplement): control (CTR; n = 5) and fish oil (FO; n = 4, 35 g/day/ram). Diets were fed for 70 days during the physiological breeding season. After a 21‐day dietary adaptation period, semen was collected weekly from each ram by an artificial vagina. Sperm classical parameters were determined by the computer‐assisted sperm analyzer system (CASA), and it was prepared for IVF process by swim‐up technique. These evaluations were performed during the first and last weeks of sampling. Intracellular ROS level and spermatozoa death incidence were detected by flow cytometry on a weekly basis after adaptation. Data were analysed with SPSS 15. The volume, concentration (3.6 and 2.7 × 10⁹/ml) and sperm progressive motility (60 and 48%) were significantly improved in the FO group compared with the CTR (p < 0.05). A comparison of two‐cell stage embryos following IVF in the two groups showed a significantly higher fertilization rate in the FO group (56%) compared with the CTR (49%). Superoxide anion (O₂^?) rate was significantly lower (p < 0.05) at the third week of sampling in the FO. Although the H₂O₂ rate was numerically lower in the FO group compared with the CTR, this difference was not significant. In addition, apoptosis showed a significant difference in the third week of sampling (15 and 30% for FO and CTR, respectively; p < 0.05). Overall, adding fish oil to the ram diet not only improved sperm quality and IVF results, it also could reduce oxygen‐free radicals and the incidence of spermatozoa death.     

Fungal diseases of fish.

Fungal diseases of fish have become increasingly important over the past 20 years. The traditional "fungi" are comprised of members from several different taxonomic kingdoms. Saprolegnia and other typical water molds are the "classic" secondary invaders, infecting more superficial areas of the body and requiring compromise of the exterior of the fish, poor water quality, or general immunosuppression. An increasing number of other environmental fungi are being reported from diseased fish, further testament to the opportunistic nature of many fungi. Common procedures such as air bladder deflation for many marine species collected at depth under nonsterile conditions may result in fungal infections of the swim bladder. Some fungi such as Aphanomyces and Fusarium can cause more invasive or systemic disease, often associated with changes in environmental factors such as temperature and salinity. Other fungi such as I. hoferi can be even more insidious and chronic, mimicking mycobacteriosis to a degree. Fungal diseases, in general, are very difficult to control or treat once they have taken hold. Prevention is, as always, the best medicine. Increased knowledge of basic biology will help guide treatment and control methods. Further research on general predisposing factors, species susceptibilities, immune system effects and other protective mechanisms in fish and more effective chemotherapeutics for external and systemic infections are needed.     

Technical note: Modifying Atlantic salmon (Salmo salar) jumping behavior to facilitate innovation of parasitic sea lice control techniques

Industrial salmon farms are reservoirs of parasitic sea lice (Lepeophtheirus salmonis and Caligus spp.), which causes both production inefficiencies and contributes to population-level declines of wild salmon and trout. Current control methods vary in effect and stimulate controversy by the discharge of chemicals into the environment. An alternate control method uses a thin, chemical-infused oil layer on the sea surface. As farmed salmon jump through the surface, the treatment makes contact with the lipophilic carapace of sea lice and kills them. To enhance the effectiveness of this method, we tested whether the natural jumping behavior of salmon could be increased and directed. In a 2,000-m(3) experimental sea-cage, we removed the ability of groups of salmon to access the surface for different periods (0 to 48 h) and measured their surface behaviors after the surface became accessible again. Surface removal for 24 and 48 h induced 93% of salmon to jump in the 2 h after surface access was reinstated, a result that differed (P < 0.001) from the shorter duration (0 to 12 h) treatments. Salmon without surface access for 24 and 48 h jumped 2 to 3 times more often (P < 0.001), and made their first jump 2 to 3 times sooner (P = 0.003) on average after surface access became available than salmon in the shorter duration treatments. Our results indicate that removal of surface access for short periods may lead to loss of air from the physostomous swim bladder and cause negative buoyancy. This creates a behavioral drive for salmon to jump, swallow air and fill their swim bladders once surface access is reinstated. By combining the increased jumping behavior induced by this technique with a floating, oil-infused treatment, efficiency of sea lice treatments may be improved and treatment chemicals can be re-collected, thus decreasing environmental pollution.     

Mixed Metazoan and Bacterial Infection of the Gas Bladder of the Lined Seahorse—A Case Report

Abstract

Five wild-caught Lined Seahorses Hippocampus erectus from an aquarium system presented with altered buoyancy and distended upper trunks. Radiography of one specimen revealed a reduced air volume in the gas bladder. Pneumocystocentesis revealed a brown exudate of numerous leukocytes, parasite ova, and Gram- and acid-fast-positive bacilli under wet mounts and stains. Necropsies revealed enlarged, friable kidneys and distended gas bladders containing copious purulent exudate, necrotic tissue, and adult digeneans Dictysarca virens. Bacterial isolates from exudate cultures grown on Lowenstein–Jensen medium were identified as Gordonia sp. and Mycobacterium poriferae by high-performance liquid chromatography and 16S ribosomal DNA sequencing. Histopathology demonstrated a histiocytic response in kidney and gas bladder exudate, inflammation of the gas bladder wall, and infection of the gas bladder lumen with parasite ova and acid-fast-positive and Gomori's methenamine silver-positive bacilli. Praziquantel is prescribed for digenean infections but dissolves incompletely in seawater and is toxic to this host. Eradication of intermediate host vectors is a management option. Treatment of Gordonia infection has not been addressed in nonhuman animals, and there is no known effective treatment for Mycobacterium spp. infection in fishes. This is the first case report of digenean infection of the gas bladder in a syngnathid, Gordonia sp. infection in a nonhuman animal, and M. poriferae infection in a fish.

Received May 25, 2012; accepted October 12, 2012     

A technique for resection of invasive tumors involving the trigone area of the bladder in dogs: preliminary results in two dogs

Objective— To describe a surgical technique for resection of the entire bladder neck, including the trigone and proximal urethra in dogs with invasive tumors causing life-threatening urinary tract obstruction.
Study Design— Clinical case reports.
Animals— Dogs (n=2) with bladder tumors.
Methods— Circumferential excision of the bladder neck and proximal urethra with preservation of the neurovascular pedicles was performed to remove a rhabdomyosarcoma (dog 1) and a transitional cell carcinoma (dog 2) involving the trigone and bladder neck that were causing urinary tract obstruction. Reconstruction of the bladder and proximal urethra included bilateral ureteroneocystostomy. Adjuvant chemotherapy was administered postoperatively to both dogs.
Results— Postoperatively, dogs 1 and 2 were continent after 7 and 17 days, respectively, and regained normal urinary function after resolution of a transient pollakiuria. Dog 1 had no evidence of local or regional recurrence; however, a large solitary pulmonary metastatic lesion was diagnosed 8 months later. The dog was euthanatized despite a lack of clinical signs. Dog 2 had at least 1 metastatic lesion in the abdominal wall 6 months later and was euthanatized at 580 days because of renal failure.
Conclusion— En-bloc removal of the bladder neck and proximal urethra with preservation of the dorsal vascular and nervous pedicles, although a technically challenging procedure, can be performed without associated urinary incontinence or bladder wall necrosis.
Clinical Relevance— In dogs with invasive bladder tumors causing life-threatening urinary tract obstruction, resection of the bladder neck and proximal urethra should be considered as a promising surgical alternative to urinary diversion.     

Effects of general anaesthesia on static respiratory compliance in dogs

The effect of anaesthesia on total, pulmonary and chest wall static respiratory compliance was investigated in healthy spontaneously breathing dogs undergoing orthopaedic surgery. Total compliance fell by 26 per cent from the baseline measurement within 25 minutes of the first measurement (P less than 0.01), while pulmonary and chest wall compliances fell by 34 per cent and 40 per cent, respectively (P less than 0.01). Pulmonary compliance ceased to fall after 50 minutes, but chest wall compliance was still declining after 70 minutes. The decline in compliance could be prevented by periodic full lung inflation, with a significant difference being found between inflated and uninflated dogs (P less than 0.01). The reduction in compliance during anaesthesia is believed to be a consequence of reduced functional residual capacity and the development of lung tissue atelectasis.     

Use of Laparoscopy for the Evaluation of the Reproductive Status of Tench (Tinca tinca)

The aim of the study was to evaluate the use of laparoscopy for the assessment of the reproductive tract and stage of gonadal development of the tench (Tinca tinca). Laparoscopy was carried out from February to March 2009, on 30 anesthetized tenchs, 15 males and 15 females, of approximately 250 g bodyweight and 30 cm length, using a 1.9‐mm rigid cystoscope. Male and female gonads, attached to the swim bladder, were visualized. Testes were orange with a striped appearance. Mature ovaries were cluster‐shaped and whitish. Histological samples were collected, from the reproductive organs of both the sexes, with a forceps and showed the presence of gametes at different stages of maturity. The application of this minimally invasive diagnostic imaging technique could clinically be used as a powerful tool to evaluate the gender and to establish the reproductive status of tench and other fish.     

Laparoscopically implanted tissue expander radiotherapy in canine transitional cell carcinoma

Organ motion and injury to adjacent structures limit curative treatment of intraabdominal tumors with external beam radiotherapy. We evaluated the use of Laparoscopically Implanted Tissue Expander Radiotherapy (LITE-RT) to exclude critical structures during irradiation of the urinary bladder in two dogs with transitional cell carcinoma (TCC) using helical tomotherapy. Dogs had histologically confirmed bladder TCC with no metastasis. A custom-shaped tissue expander was placed between the colon and bladder laparoscopically in one dog and during laparotomy in the other. The prescribed radiation dose was 45 Gy to 98% volume of the bladder in 18 fractions of 2.5 Gy. Tumor response and normal tissue effects were monitored with cystoscopy and colonic biopsies before treatment and 3, 6, and 15 months after treatment. Based on treatment plans from inflated vs. deflated tissue expander CT images, there was a mean dose reduction to the colon of 53% and 31% for the two dogs. Interfractional target repositioning was possible by using volumetric megavoltage computed tomography helical tomotherapy. Both dogs had no clinical signs of chronic colitis but did experience mild cystitis during treatment. Tissue expanders became detached, requiring an additional surgery for reattachment, in both dogs. One dog developed a fibrous adhesion resulting in bladder rupture during inflation, which necessitated early device removal. One dog was euthanized for tumor-associated ureteral obstruction at 8 months while the other is alive at 21 months. We conclude that LITE-RT shows promise in treatment of canine bladder TCC due to lack of acute colitis and enteritis.