CASE REPORT HEPATIC ENCEPHALOPATHY IN A RED-TAILED BOA (BOA CONSTRICTOR IMPERATOR) Marco Di Giuseppe, DVM, PhD, GPCert (ExAP), Matteo Oliveri, DVM, PhD, Manuel Morici, DVM, PhD, Giacomo Rossi, DVM, PhD, Dip. ECZM (Wildlife Population Health), and Filippo Spadola, DVM, PhD
Abstract A 5-year-old female red-tailed boa (Boa constrictor imperator) was presented for abnormal neurologic behavior. Ultrasound examination revealed an enlarged liver, with rounded margins and hypoechoic areas. A complete snake virus polymerase chain reaction (PCR) proﬁle was performed together with diagnostic blood testing. The snake virus PCR proﬁle results were negative. Supportive treatment for the patient consisted of ﬂuid therapy and nutritional support, supplemented with carnitine. Lactulose was administered orally every 24 hours. The snake died 3 weeks after the initial presentation. Histopathological examination of the liver showed extensive necrotic degeneration with hepatocytic centrilobular organization and cholestasis. Histopathology of the central nervous system (CNS) revealed a degenerative pattern of neurons, and a hyperplastic aspect of the microglial cells, morphologically similar to Alzheimer type II astrocytes. The postmortem examination results indicate that the neurological signs were a consequence of hepatic encephalopathy (HE). Reptiles with hepatic disease may show a wide variety of clinical signs. The last stage of liver diseases is often HE. Diagnostic procedures include hematology, serum/plasma biochemistry, echography, and biopsy. The prognosis for a patient that is presented with clinical signs of HE is guarded at best. Recommended treatment for reptile patients that are diagnosed with HE is ﬂuid support and more speciﬁc hepatic therapeutic agents, including lactulose, silymarin, and carnitine. Copyright 2017 Elsevier Inc. All rights reserved. Key words: hepatopathy; neurology; neuronal degeneration; snakes
5-year-old female red-tailed boa (Boa constrictor imperator) was presented for abnormal neurologic behavior. The snake was part of a large snake collection, and the owner described the patient as having a prolonged period of anorexia (approximately 2 months). The boa had no history of previous medical issues. Physical examination revealed a marked alteration of the neurological status, including stargazing, absence of the righting reﬂex, stupor, and reluctance to move (Fig. 1). Palpation failed to reveal any intracoelomic masses. Fresh fecal stain and ﬂoatation were performed. Ultrasound examination revealed an enlarged liver, with rounded margins and hypoechogenic areas (Fig. 2). Owing to the high prevalence of virus–associated neurological syndromes in snakes, a complete snake virus polymerase chain reaction (PCR) proﬁle (adenovirus, arenavirus, paramyxovirus/ferlavirus, and reovirus) was performed using a cloacal swab and blood samples. With a modiﬁed hemagglutination inhibition assay, serum antibodies against ophidian paramyxovirus were determined. To verify infection with arenavirus (inclusion body disease), the presence of inclusion bodies in red blood cells was examined in the blood smear (hematoxylin and eosin stain), and a biopsy of the esophageal tonsil was taken for histology.
From the Centro Veterinario per Animali Esotici, Palermo, Italy; the Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic; the Department of Veterinary Science, Veterinary Teaching Hospital, University of Messina, Messina, Italy; and the School of Biosciences and Veterinary Medicine, University of Camerino, Matelica, Italy. Address correspondence to: Manuel Morici, DVM, PhD, GPCert (ExAP), Department of Veterinary Science, Veterinary Teaching Hospital, University of Messina, Polo universitario SS Annunziata, 98168 Messina, Italy. E-mail: [email protected]
Ó 2017 Elsevier Inc. All rights reserved. 1557-5063/17/2101-$30.00 http://dx.doi.org/10.1053/j.jepm.2017.01.029
Journal of Exotic Pet Medicine 26 (2017), pp 96–100
TABLE. Hematology and serum biochemistry panel results in the Boa constrictor imperator affected with hepatic encephalopathy
FIGURE 1. Clinical examination of the boa constrictor. The animal showed signiﬁcant abnormalities of its neurological status, including stargazing, absence of the righting reﬂex, stupor, and reluctance to move.
The fresh fecal stain and ﬂotation failed to reveal any possible parasite that would have caused the clinical signs (Acanthoamoeba spp.). Both the PCR proﬁle and hemagglutination inhibition assay tested negative. The plasma biochemistries and complete blood count (Table) revealed increased concentrations of creatine kinase (170 U/L), phosphorous (8.8 mg/dL), and sodium (4170 mmol/L). No inclusion bodies were present in the blood smear. Histology of the esophageal tonsil showed no signs of basophilic intracytoplasmic inclusions attributable to arenavirus. Supportive treatment consisted in ﬂuid therapy (20 mL/kg of reptile solution) and nutritional support (2 mL/kg orally, Oxbow Carnivore Care; Oxbow Animal Health, Murdock, NE USA) supplemented with carnitine (Rossovet, Pﬁzer Italia, Italy) and lactulose (0.5 mL/kg orally, every 24 hours; Laevolac, Roche, Switzerland). Unfortunately, the snake died 3 weeks after its initial presentation. Necropsy revealed an enlarged and pale liver (Fig. 3). Histopathology of the liver showed extensive necrotic degeneration with hepatocytic centrilobular organization and cholestasis (Fig. 4). No abnormalities were found in the lungs. The esophageal tonsil was slightly reactive. No other macroscopic pathological alterations were noticed. Histopathology of the
AST Bile acids (BA) CK UA GLU Caþþ PHOS TP ALB GLOB Kþ Naþ WBC HCT RBC
9 o35 170 4.1 62 15.6 8.8 9.6 2.0 7.6 0.0 4170 2.4 20 0.55
U/L Umol/L U/L mg/dL mg/dL mg/dL mg/dL g/dL g/dL g/dL mmol/L mmol/L 103/μL % 106/μL
References 5 to 35 53 to 138 1.2 to 5.8 10 to 60 10 to 22 2.6 to 4.9 4.6 to 8.0 1.9 to 5.3 2.2 to 6.9 3.0 to 5.7 130 to 152 0.88 to 22.5 10 to 45 0.16 to 2.1
ALB, albumin; AST, aspartate aminotransferase; BA, bile acids; CK, creatine kinase; GLU, glucose; GLOB, globulins; HCT, hematocrit; PHOS, phosphorus; RBC, red blood cell; TP, total protein; UA, urinalysis; WBC, white blood cell.
central nervous system (CNS) revealed a degenerative pattern of neurons, and a hyperplastic (or binucleated) aspect of the microglial cells, morphologically similar to Alzheimer type II astrocytes (Fig. 5).1 DISCUSSION In snakes, neurological abnormalities may be caused by several disease conditions, including exposure to toxins, trauma, neoplasia, meningitis (viral, bacterial, or mycotic), osteomyelitis, thiamine deﬁciency, and hepatic dysfunction.2-12 Viral diseases involving the CNS are frequently diagnosed in snakes. Inclusion body disease (arenavirus) is a common condition in ophidian medicine.13 Inclusion body disease is characterized by nonsuppurative meningoencephalitis and
FIGURE 2. Boa constrictor. Ultrasound examination showing enlarged liver, with rounded margins and hypoechogenic areas. Giuseppe et al./Journal of Exotic Pet Medicine 26 (2017), pp 96–100
FIGURE 3. Boa constrictor. An enlarged and pale liver was noted at the time of necropsy.
severe neurological signs (e.g., stargazing, incoordination, and ataxia).14,15 The snake patient infected with ophidian paramyxovirus is usually presented with pneumonia and respiratory clinical signs. However, Jacobson et al.16,17 and Orós et al.18 associated paramyxovirus with neurological dysfunction in rattlesnakes. Reovirus has been isolated from the brain of a Crotalus viridis showing abnormal neurologic signs, however, no histologic lesions were identiﬁed in the CNS of that snake.19 Oliveri and Cermakova diagnosed reovirus in a Morelia viridis that was presented with severe polyneuropathy, stupor, and ataxia (personal communication). Adenovirus infection has been reported in snakes.20-25 Raymond et al.26 reported foci of gliosis within the CNS, and several glial and endothelial cells contained intranuclear adenovirus-like inclusion bodies in infected snakes. Acanthamoeba spp. have also been correlated with neurological disease in snakes.27 However, none of the disease conditions listed above were identiﬁed in the snake described in this
FIGURE 4. Boa constrictor (histopathology of the liver). Extensive necrotic degeneration was observed with hepatocytic centrilobular organization and cholestasis. Note the presence of areas of swollen hepatocytes and foci of chronic inﬂammation (big arrow). Areas of melanomacrophages concentration are also evident (small arrowhead). H&E, scale bar ¼ 500 μm. H&E, hematoxylin and eosin.
FIGURE 5. Boa constrictor. Histopathology of the central nervous system revealed a degenerative pattern of neurons, and a hyperplastic (or binucleated) aspect of the microglial cells, morphologically similar to Alzheimer type II astrocytes, clinical conditions seen in liver encephalopathy. H&E, scale bar ¼ 150 μm. H&E, hematoxylin and eosin.
report. As previously stated, the histopathology results of the red-tailed boa showed extensive necrotic degeneration of the liver, with hepatocytic centrilobular organization and cholestasis (Fig. 4), and a degenerative pattern of neurons together with a hyperplastic (or binucleated) aspect of the microglial cells, morphologically similar to Alzheimer type II astrocytes (Fig. 5). The postmortem examination results indicate that the neurological signs were a consequence of hepatic encephalopathy (HE). Reptiles with hepatic disease may show a wide variety of clinical signs. Lethargy, chronic anorexia, weight loss, and gastrointestinal and neurological signs are common. The last stage of liver disease often results in HE. Clinical signs of HE are extremely variable (e.g., circling, weakness, ataxia, ptyalism, seizures, and coma). The pathophysiology of HE is not completely known. Hazell and Butterworth28 proposed a synergistic effect involving liver failure and ammonia detoxiﬁcation, increased cerebral inﬂammatory proteins, impaired brain perfusion with development of astrocytes swelling, and neuronal edema. Chen et al.29 propose an alteration of CNS functions during HE due to dendritic morphology remodeling of cortical and hippocampal pyramidal neurons. Reduction of the dendritic spine density causes an increase of the motor evoked potential threshold and a prolonged central motor conduction time. Hematology of the HE affected patient often shows anemia, heterophilia and monocytosis. Biochemistries frequently reveal high values of aspartate aminotransferase, gamma glutamyltransferase, alkaline phosphatase, alanine
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aminotransferase, and lactate dehydrogenase, but none of these analytes are truly liver-speciﬁc enzymes in reptiles. Bile acids may eventually prove to be a promising hepatic marker.30 Diagnostic imaging techniques are also clinically useful to detect changes in size or appearance of the liver. An endoscopically obtained tissue biopsy sample is considered as a useful diagnostic tool to diagnose liver disease.31 Prognosis of the patient exhibiting clinical signs of HE is guarded at best. Recommended treatment for snakes that are diagnosed with HE involves ﬂuid administration (avoidance of solutions that contain lactate), along with more speciﬁc hepatic therapeutic agents. Carnitine (250 mL/kg orally) is a derivate of the amino acid lysine, which is involved in the transport of the acetyl coenzyme A through the cellular membrane of the hepatocyte.31,32 Lactulose is commonly used in treating hyperammonemia, which is believed to be one of the underlying causes of HE. Lactulose (0.5 mL/kg orally) is fermented by the gut ﬂora into metabolites that acidify the colon. An acidic environment turns freely diffusible ammonia (NH3) into ammonium (NHþ 4 ), which can no longer be absorbed.33-35 Silymarin (milk thistle) has a long history of use in the treatment of liver disease, predominantly in controlling inﬂammation and limiting uptake of toxins. In the human patient, silymarin exerts membrane stabilizing and antioxidant activity and promotes hepatocyte regeneration; furthermore, it reduces the inﬂammatory reaction and inhibits ﬁbrogenesis in the liver.36 The use of silymarin to treat HE in reptiles appears to be promising. REFERENCES 1. Diemer NH, Klinken L: Astrocyte mitoses and Alzheimer type I and II astrocytes in anoxic encephalopathy. Neuropathol Appl Neurobiol 2:313-321, 1976 2. Craig LE, Wolf JC, Ramsay EC: Spinal cord glioma in a ridge-nosed rattlesnake (Crotalus willardi). J Zoo Wild Med 36:313-315, 2005 3. Done L: Neurological disorders, in Mader D (ed): Reptile Medicine and Surgery. St. Louis, MO, Elsevier/Saunders, pp 852-857, 2006 4. Gyimesi SS, Garner MM: Pituitary adenoma in a Dumeril's ground boa, Acrantophis dumerili. J Herpetol Med Surg 17: 16-18, 2007 5. Cole GA, Rao DB, Steinberg H: Suspected vitamin E and selenium deﬁciency in a veiled chameleon (Chameleo calyptratus). J Herpetol Med Surg 18:113-116, 2008 6. Anderson ET, Troan BV, Stringer EM: Cerebral xanthoma in a long-nosed snake (Rhinocheilus lecontei). J Herpetol Med Surg 20:58-60, 2010 7. Wyneken J: Reptilian neurology: anatomy and function. Vet Clin North Am Exot Anim Pract 10:837-853, 2007
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