In small animal medicine, various antemortem techniques for the collection of liver tissue samples for diagnostic purposes have been tried and tested. Currently, percutaneous, endoscopic, or open surgical procedures are most commonly used to collect samples for cytologic or histologic examination.1–3 Percutaneous biopsy procedures allow liver tissue samples to be safely collected by use of biopsy needles in dogs that weigh > 10 kg (22 lb); fine-needle aspiration by use of smaller gauge hypodermic needles is preferred in smaller animals.1,2 In most instances, collection of such samples is performed with ultrasound guidance. Comparisons of liver biopsy specimens and fine-needle aspiration samples obtained from dogs and cats have revealed that findings of cytologic examination of aspirates is only diagnostic in 30% to 61% of samples, compared with findings of histologic examination of tissue specimens.4,5 Compared with wedge tissue samples collected surgically, large-gauge–needle biopsy specimens yielded a diagnosis in only 48% of cases, and findings from examination of the latter should be interpreted with caution.6 Although the diagnostic value of surgical biopsy procedures is greater than that of needle biopsy and fine-needle aspiration techniques, the invasiveness of those procedures is also greater; however, that disadvantage has been largely overcome since the development of minimally invasive endoscopic techniques.3,7,8 Retrospective studies9,10 in humans have revealed comparable diagnosis rates for laparoscopic and laparotomy-associated liver biopsy procedures, but application of endoscopy has the advantage of decreased duration of hospitalization.
In reptile medicine, the diagnostic approach to liver disease is similar to that of domesticated animals, and typically, results of an examination of liver tissue samples are required for a definitive diagnosis.11 Large-gauge–needle biopsy is seldom performed in small reptiles because of the dangers of iatrogenic trauma, and ultrasound-guided fine-needle aspiration frequently yields specimens from which a diagnosis cannot be made because of the difficulties of microscopic interpretation without tissue architecture. In snakes that weigh > 1 kg (2.2 lb), percutaneous ultrasound-guided needle biopsy has provided diagnostic samples; however, 2 to 4 attempts were required to obtain liver tissue, and penetration of the gastrointestinal tract was a complication.12 The failure of the procedure was associated with movement of the snake, and anesthesia was therefore deemed essential. Endoscopic liver biopsy has been advocated for a variety of reptile species, even in animals that weigh < 100 g (0.22 lb).13–16 Anesthesia is required, but to our knowledge, no complications have been reported with use of appropriate anesthetic techniques. The purpose of the study reported here was to establish a safe and effective endoscopic technique for collection of liver biopsy specimens from lizards by use of a 2.7-mm rigid endoscope system that is commonly available in zoologic veterinary practice.
Adult iguana diet, Ziegler Bros Inc, Gardners, Pa.
VT-5000, small animal ventilator, BAS Vetronics, Bioanalytical Systems Inc, West Lafayette, Ind.
67065C, operating sheath for 64018BSA telescope, 14.5-F outer diameter, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
64018BSA, autoclavable Hopkins rigid telescope, 2.7 mm × 18 cm working length, 30°, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
69235106, veterinary video camera II, 9219-B Sony medical grade monitor, 201320-20 xenon light source, 26012C CO2 insufflator, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
67161Z, flexible biopsy forceps, 5-F × 34-cm, Karl Storz Veterinary Endoscopy America Inc, Goleta, Calif.
Cholongitas E, Senzolo M, Standish R, et al. A systematic review of the quality of liver biopsy specimens. Am J Clin Pathol 2006;125:710–721.
Wang KY, Panciera DL, Al-Rukibat RK, et al. Accuracy of ultrasound-guided fine-needle aspiration of the liver and cytologic findings in dogs and cats: 97 cases (1990–2000). J Am Vet Med Assoc 2004;224:75–78.
Cole TL, Center SA, Flood SN, et al. Diagnostic comparison of needle and wedge biopsy specimens of the liver in dogs and cats. J Am Vet Med Assoc 2002;220:1483–1490.
Twedt DC, Monnet E. Laparoscopy: technique and clinical experience. In:McCarthy TC, ed.Veterinary endoscopy for the small animal practitioner. St Louis: Elsevier, 2005;357–385.
Orlando R, Lirussi F, Okolicsanyi L. Laparoscopy and liver biopsy: further evidence that the two procedures improve the diagnosis of liver cirrhosis. A retrospective study of 1,003 consecutive examinations. J Clin Gastroenterol 1990;12:47–52.
Hernandez-Divers SJ. Diagnostic techniques. In:Mader DR, ed.Reptile medicine and surgery. 2nd ed. St Louis: Elsevier, 2005;490–532.
Ramiro I, Ackerman N, Schumacher J. Ultrasound-guided percutaneous liver biopsy in snakes. Vet Radiol Ultrasound 1993;34:452–454.
Hernandez-Divers SJ. Diagnostic and surgical endoscopy. In:Raiti P, Girling S, ed.Manual of reptiles. 2nd ed. Cheltenham, England: British Small Animal Veterinary Association, 2004;103–114.
Hernandez-Divers SJ, Hernandez-Divers SM, Wilson GH, et al. A review of reptile diagnostic coelioscopy. J Herpetol Med Surg 2005;15:16–31.
Esposito C, Garipoli V, Vecchione R, et al. Laparoscopy-guided biopsy in diagnosis of liver disorders in children. Liver 1997;17:288–292.
Hernandez-Divers SJ, Stahl S, Stedman NL, et al. Renal evaluation in the green iguana (Iguana iguana): assessment of plasma biochemistry, glomerular filtration rate, and endoscopic biopsy. J Zoo Wildl Med 2005;36:155–168.
Hernandez-Divers SJ, Shearer D. Pulmonary mycobacteriosis caused by Mycobacterium haemophilum and M marinum in a royal python. J Am Vet Med Assoc 2002;220:1661–1663.