Author’s Accepted Manuscript NEPHRECTOMY IN A CASE OF INFECTIOUS NEPHRITIS IN A MEXICAN KINGSNAKE (LAMPROPELTIS GETULA NIGRITA) Adrián Melero, Carlo Anselmi, Albert Canturri, Jaime Martorell www.sasjournal.com
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To appear in: Journal of Exotic Pet Medicine Cite this article as: Adrián Melero, Carlo Anselmi, Albert Canturri and Jaime Martorell, NEPHRECTOMY IN A CASE OF INFECTIOUS NEPHRITIS IN A MEXICAN KINGSNAKE (LAMPROPELTIS GETULA NIGRITA ), Journal of Exotic Pet Medicine, http://dx.doi.org/10.1053/j.jepm.2017.08.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Nephrectomy in a Case of Infectious Nephritis in a Mexican Kingsnake (Lampropeltis getula nigrita) Adrián Melero DVM Carlo Anselmi DVM Albert Canturri DVM Jaime Martorell, DVM, PhD, Dip. ECZM (Small Mammal) From the Fundació Hospital Clínic Veterinari (Melero, Anselmi, Martorell), 2. Departament de Medicina i Cirurgia Animal (Martorell), 3. Departament de Medicina i Sanitat Animals (Canturri), Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain. Address correspondence to Adrián Melero DVM, Fundació Hospital Clínic Veterinari, Facultat de Veterinaria, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cedanyola del Valles), Barcelona, Spain. Email address: [email protected]
Tel: 0034 935811090 Abstract A 10-year-old, intact, captive-born female Mexican Black Kingsnake (Lampropeltis getula nigrita) was presented with a 1-week history of caudal coelomic distention. On physical examination a 5cm in length, soft non-mobile mass was identified in the caudal third of the coelomic cavity, 4cm cranially to the cloaca. Survey radiographic images revealed an increased soft tissue opacity within the affected area with variable sized, irregular mineralized structures. An intracloacal contrast study showed contrast retention in the cloaca. The retention of contrast within the cloaca was compatible with the presence of a mass compressing the rectum. An ultrasound evaluation confirmed a 2 x 3cm, oval well-defined mass with an echogenic capsule. Computed tomographic imaging revealed a heterogeneous mass with some mineral areas with irregular shape and size. The mass was excised and the tissue submitted for histopathology and culture. The histopathological and microbiological diagnosis of the mass was purulent interstitial nephritis with presence of multiple histiocytic granulomas that contained intralesional bacteria (Morganella morganni). The animal responded well to the surgical removal of the mass and subsequent medical treatment.
Lampropeltis getula nigrita; Morganella morganii
(Lampropeltis getula nigrita) was presented with a 1-week history of caudal coelomic distention. The animal, purchased from a pet shop 9.5 years prior to presentation, belonged to a private collection. The husbandry and nutrition, including diet, illumination, temperature, and humidity, were considered appropriate for this species. It was housed alone in a 80 x 50 x 50 cm terrarium and was fed a dead mouse on a weekly basis. On physical examination, the snake weighed 725g and was alert, responsive, with a good body condition score (3/5). A 5cm in length, soft nonmobile mass was identified in the caudal third of the coelomic cavity, 4cm cranially to the cloaca. A blood sample using intracardiac venipuncture was collected while the patient was manual restrained and submitted for a complete blood count (CBC) and plasma chemistry panel. The CBC showed a severe leukocytosis with monocytosis and lymphocytosis. The plasma biochemistry panel was unremarkable (Table 1).1 The patient was sedated in an induction chamber with 4% isoflurane and subsequently anesthetized via direct tracheal intubation with a 2-mm diameter uncuffed tracheal tube for whole-body radiographic imaging, ultrasound (US), and computed tomography (CT). The survey radiographic study revealed an increased opacity of the soft tissue in the clinically affected area that consisted of multiple, irregular mineralized structures.
After intracloacally contrast administration15ml/kg,
intracloacally, once (Gastrografin; Bayer Hispania S.L., Barcelona, Spain) there was contrast retention within the cloaca. This retention was compatible with the presence of a mass compressing the caudal intestinal tract (Fig. 1). The US evaluation confirmed a 2 x 3cm, oval well-defined mass with an echogenic capsule. The mass was determined to have hypoechoic content with hyperechoic particles in suspension. Cranially and caudally at this zone, there were some hyperechoic areas with a clean acoustic shadow (Fig. 2). To better define the lesion, a computed tomography (CT) study was performed. The CT study revealed a heterogeneous mass causing a mass effect on adjacent structures. This mass presented mineralization and was of irregular shape (Fig. 3). Based on the lesions identified through diagnostic imaging, the presumptive diagnosis was urolithiasis and the right renal mass was compatible with an abscess, granuloma, cyst, or neoplasia. The following day, the snake was prepared for an exploratory coeliotomy. The patient was premedicated with tramadol 10 mg/kg intramuscularly, every 12 hours (Tramadol; Normon, Laboratorios Nomon S.A., Madrid, Spain), midazolam 0,5 mg/kg intramuscularly, once (Midazolam; Normon, Laboratorios Nomon S.A., Madrid, Spain), and preventive antibiotherapy with ceftazidime 20mg/kg intramuscularly, every 72 hours (Fortam; GlaxoSmithKline, S.A., Madrid, Spain). A 24-gauge intravenous catheter was placed in the ventral coccygeal vein for administration of crystalloids fluids 10ml/kg/h, intravenous (Lactato de Ringer; Hartmann Braun, B. Braun Medical, S.A., Barcelona, Spain). The patient was induced with alfaxalone 5mg/kg, intravenous (Alfaxan; Dechra Veterinary Products SLU, Barcelona, Spain), maintained with 3-4% sevoflurane (SevoFlo; Abbot Laboratories S.A., Barcelona, Spain) in 100% oxygen (1,5 L),
and was provided positive-pressure ventilation (SAV03 - Small Animal Ventilator, Vetronic Services LTD, Devon, UK) throughout the surgical procedure. Anesthetic monitoring included heart rate, respiratory rate, capnography, and cloacal temperature. The heart rate was monitored using an ultrasonic Doppler flow (Vet BP Doppler, Mano Medical, Warsaw, Poland). The ultrasound crystal was placed over the heart projection on the ventral skin. The respiratory rate was controlled with the artificial ventilator described above; the capnography was monitored with a capnographer (Capnovet-10, Vetronic Services LTD, Devon, UK). The animal was placed in a dorsal recumbency. The surgical area was prepared aseptically with tempered physiological saline and chlorhexidine solution for a standard coeliotomy procedure. A 10cm incision was made craniocaudally at the lateral right margin of the caudal third of the body, where the scutes and scales were in apposition. Once the skin incision was complete, the ventral musculature and fascial membranes were opened with blunt dissection. A 5 cm, soft, oval and lobular mass with a cyst was observed in the renal right area. Cranially and caudally to the mass there were several nodules of different size. The normal architecture of the kidney was completely altered. The cranial portion of the right ureter was completely separated from the right kidney and was full of urate calculi (Figs. 4A and 4B). Once the kidney was localized, a nephrectomy was performed through blunt dissection of the retroperitoneal membrane which allowed adequate exposure of the masses and the right kidney. The renal vasculature (afferent renal vein, renal arteries, and efferent renal vein) was isolated and hemostasis
Medizintechnik GmbH, Eisenbahnstr, Germany). The ureter was dissected and completely removed. At this time all nodules along with the right kidney were completely dissected and a right total nephrectomy and ureterectomy were performed. The coelomic cavity was flushed with saline solution after which the muscular layer was closed using a simple continuous suture pattern with 4-0 polyglactin 910 (Vicryl Ethicon, Johnson and Johnson, Somerville NJ USA). The skin was closed using an interrupted horizontal mattress suture pattern with 3-0 polyglactin 910 (Vicryl Ethicon, Johnson and Johnson, Somerville NJ USA). A section of the mass was collected for bacteriology culture and sensitivity and the rest of the masses, the right ureter and kidney were submitted for histological analysis. Postoperative treatment consisted of antibiotic therapy with ceftazidime (20mg/kg intramuscularly, every 72 hours (Fortam; GlaxoSmithKline, S.A., Madrid, Spain), analgesia with tramadol (10 mg/kg intramuscularly, every 12 hours (Tramadol; Normon, Laboratorios Nomon S.A., Madrid, Spain), meloxicam 0.2 mg/kg intramuscularly, every 12 hours (Metacam; Boehringer Ingelheim España, S.A., Barcelona, Spain)
and fluid therapy based on
intracoelomic crystalloids with ringer lactate 20ml/kg/day (Lactato de Ringer; Hartmann Braun, B. Braun Medical, S.A., Barcelona, Spain) supplemented with 2.5% glucose. The animal was discharged 72 hours following the surgical procedure with instructions to continue the prescribed antibiotic treatment for a month and recommendations for proper husbandry and diet. A week following the surgical procedure, there were no complications noted by the owner and the snake had
a normal appetite. Two months after the nephrectomy and removal of the coelomic masses the animal had fully recovered and laid seven eggs. Morganella morganii was isolated from the submitted tissue mass which was sensitive to amikacin, cefotaxime, ceftazidime, enrofloxacin, imipenem, marbofloxacin, and trimethoprim-sulfonamide. The tissue samples were fixed in 10% neutral-buffered formalin, processed routinely, embedded in paraffin, sectioned, and stained with hematoxylin and eosin for histopathologic evaluation. Histologically, the renal mass was characterized by a large area of disorganization and loss of the renal parenchyma, with lytic necrosis and diffuse heterophilic and macrophagic inflammatory infiltrate
granulomas composed of a central core of lytic necrosis, with cellular debris and bacterial aggregates, surrounded by degenerate heterophils and peripheral abundance of macrophages (histiocytic granuloma) (Fig. 6). The lumen of the dilated right ureter contained an abundance necrotic and calcified material as that identified in the affected kidney's parenchyma.
The final diagnosis was
purulent interstitial nephritis with presence of multiple histiocytic granulomas with intralesional bacteria.
Infections of the urinary tract in reptiles have been caused by helminth parasites (Strongyloides gulae), filarial worms and trematodes (Styphlodora horrida, S. condita, S. renalis and S. eligous, etc.); protozoan such as hexamites (Hexamita parva) and entamoebas (E. invadens), coccidia (Klossiella boae,
Caryospora chelomiae, etc.); fungal (Geotrichum candidum, Mycrosporidium sp., Chrysosporium sp.); viruses (retrovirus, paramyxovirus, adenovirus, etc.) and bacteria. However, bacterial infections are considered the most common etiology associated with urinary tract infections in reptiles, with gram-negative bacteria such as Pseudomonas spp. and Aeromonas spp. frequently isolated.2,3 Morganella morganii is a gram negative enterobacteria. It is considered one of the common bacterial isolated in the gastrointestinal tract of reptiles and mammals, including humans. It rarely causes urinary tract infections due to its inability to readily grow in urine.4 In the literature, Morganella morganii has been identified as a part of the normal oral flora of Python regius, Naja atra and Trimeresurus albolabris and conjunctival flora of tortoise and turtles.5,6 In addition, M. morganii was also been isolated from a human bacterial infection associated with snakebite in Taiwan.7 Morganella morganii has also been described in a case of hemorrhagic stomatitis in a natural hybrid of Vipera ammodytes × Vipera berus; however, there have been no cases of nephritis related to this bacterium in Lampropeltis spp.8 In the described case, it is suspected that an ascending infection from the cloaca by M. morganii was the inciting cause of this disease condition. This may be both the cause and consequence of urolithiasis which finally developed into a renal abscess. The effective antibiotic therapy against Morganella morganii was established based on bacteriology culture and sensitivity. In blood tests, uric acid determination is not always a specific indicator of renal disease. Hyperuricemia in reptiles is associated with nephritis, nephrocalcinosis, and nephrotoxicity. However, the patient’s uric acid levels, before and after the surgical procedure, were within normal reference values.8
The left kidney was considered functional and the animal experienced no abnormal health issues following the removal of the right kidney. In the case presented here, a nephrectomy was performed. This surgical procedure is indicated in cases of renal neoplasms, injuries that cause significant hemorrhage or intracoelomic urine leakage, therapy resistant pyelonephritis, hydronephrosis, and ureteral abnormalities.9 Although there are several descriptions regarding surgeries in reptiles, only one citation describes, in detail, the nephrectomy in ophidian patients. One of the most important aspects to consider when performing a nephrectomy is vascularization. While manipulating the kidney during the surgical procedure, care must be taken to avoid damaging the nearby large vessels, including the dorsal aorta, renal arteries, posterior vena cava, and renal efferent vein (Fig. 7). The renal arteries must always be ligated in close proximity to the dorsal aorta. In the case presented here, only two renal arteries were observed and ligated; the other arteries were not identified, possibly due to the alteration of renal and perirenal tissue secondary to pathology.2,10 There is an intimate relationship between urinary and reproductive systems. The oviduct passes lateral to the dorsal aorta, medial and very close to kidney; therefore, care must be observed to avoid damaging these structures. In the case described above, the patient was in folliculogenesis, which increased the difficulty of the surgical procedure because of the increased development of the vasculature and reproductive system. This development increases the chances of damage due to handling while also reducing the space for manipulation of the kidney. The oviducts terminate into the posterodorsal cloaca, posterior to the ureteral openings. Oviducts should be
identified prior to the nephrectomy in order to avoid being ligated together with the ureters. Ligation of the ureters is imperative to avoid the retrograde flow and coelomic contamination of urine that has collected in the ureter.2 In conclusion, Morganella morganii should be considered in the differential diagnosis for snakes with purulent interstitial nephritis.
REFERENCES 1. Gibbons PM, Klaphake E, Carpenter JW: Hematologic and serum biochemical values of reptiles, in Carpenter JW (ed): Exotic Animal Formulary (ed 4). St. Louis, MO, Elsevier/Saunders pp 125-154, 2012 2. Divers SJ, Ness G; Lawton M, et al: Surgical anatomy of the serpentine (colubridae and boidae) kidney with particular regard to surgical nephrectomy. Proc 6th Annu Conf Assoc Rept Amph Vet pp175-179, 1999 3. Miller HA: Urinary diseases of Reptiles: Pathophysiology and Diagnosis. Sem Avian Exotic Pet Med 7(2):93-103, 1998 4. Campbell TW: Clinical pathology, in Mader DR, Divers SJ (eds): Current Therapy
Elsevier/Saunders pp 70-92, 2014 5. Di Ianni F, Dodi PL, Cabassi CS, et al: Conjunctival flora of clinically normal and diseased turtles and tortoises. BMC Vet Res 11:91, 2015 6. Shek KC, Tsui KL, Lam KK et al: Oral bacterial flora of the Chinese cobra (Naja atra) and bamboo pit viper (Trimeresurus albolabris) in Hong Kong SAR, China. Hong Kong Med J 15(3):183-90, 2009 7. Chen CM, Wu KG, Chen CJ, et al: Bacterial infection in association with snakebite: a 10-year experience in a northern Taiwan medical center. J Microbiol Immunol Infect 44(6):456-60, 2011
8. Czirják GÁ, Köbölkuti LB, Tenk M, et al: Hemorrhagic stomatitis in a natural hybrid of Vipera ammodytes × Vipera berus due to inappropriate substrate in terrarium: Pathophysiology and diagnosis. J Vet Med Sci 77(6):701-703, 2015 9. Zwart P: Renal pathology in reptiles. Vet Clin N Am Exot Anim Pract 9(1):129-159, 2006 10. Mader DR, Bennett RA: Surgery: Soft tissue, orthopedics, and fracture repair, in Mader DR (ed): Reptile Medicine and Surgery (ed 2). St. Louis, MO, Elsevier/Saunders pp 518-612, 2006
TABLE TABLE 1. Hematological and blood chemistry parameters in a Mexican king snake with infectious nephritis. Affected animal
Packed cell volume (%)
White blood cells (x
Thrombocytes (x 103/µL)
Uric acid (mg/dL)
Total protein (g/dL)
Aspartate aminotransferase (UI/L)
Creatine kinase (UI/L)
FIGURE LEGENDS FIGURE 1. Radiographic study. A) Multiple irregular opacities in parenchyma of affected right kidney. B) Intracloacal contrast media retention indicating rectal constriction (arrowhead). FIGURE 2. The ultrasound evaluation confirmed a 2 x 3cm, oval well-defined mass with an echogenic capsule. It had an hypoechoic content with hyperechoic particles in suspension. Cranially and caudally at this zone, there were some hyperechoic areas with clean acoustic shadow (arrow). FIGURE 3. The computed tomographic study revealed a heterogeneous structure causing a mass effect (arrows) on the adjacent structures such as the left kidney (*). This mass presented as a mineralized irregular shaped structure (arrowhead) in the affected area. FIGURE 4. Surgical images. (A) A 5 cm, soft, oval and lobular mass with a cyst was observed in the renal right area. Cranially and caudally to the mass there were several nodules of different size (arrows). The normal architecture of the kidney was completely alterated. (B) The cranial portion of the right ureter totally separated from the right kidney (black arrowhead) and was full of urate salts calculi (white arrowhead). FIGURE 5. Image of affected kidney. Note the large area of disorganization and loss of the renal parenchyma, with lytic necrosis and diffuse heterophilic and macrophagic inflammatory infiltrate (*). FIGURE 6. Image of the affected kidney. There were also abundant multifocal granulomas composed of a central core of lytic necrosis (*), with cellular debris and bacterial
surrounded by degenerate heterophils and
peripherally delimited by abundant macrophages (histiocytic granuloma) (arrow).
FIGURE 7. (A, B and C) Images of the kidney vascularization. CD, caudal; CR, cranial; DAA, dorsal aorta artery; I, intestine; LDC, left deferent conduct (left vas deferens); LERV, left efferent renal vein; LK, left kidney; PCV, post cava vein; RA, renal artery; RDC, right deferent conduct (right vas deferens); RERV, right efferent renal vein; RK, right kidney.