Results
AFIP Wednesday Slide Conference - No. 29
22 May 1996
Conference Moderator: Dr. Donald K. Nichols
Diplomate, ACVP
Department of Pathology
National Zoological Park Washington, D.C. 20008
Case II - 33735, 33733, or 33709
(AFIP 2503649)
Signalment: Acanthodraco vitticeps (inland bearded dragon).
Necrotic hepatocytes in the liver of a bearded dragon. Almost every is karyomegalic as the result of a large smudgy basophilic adenoviral inclusion. (HE, 400X, 48K)
History: The sections are drawn from three representative cases in an outbreak of sudden deaths of 80% of a batch of 4 to 8-week-old captive-bred bearded dragon hatchlings that occurred over several weeks. No signs of ill-health had been observed in the parent animals; Salmonella spp. had been isolated sporadically from fecal culture of both parents and hatchlings. The animals were housed in several separate batches, all of which were affected. No premonitory signs of illness were observed; affected animals were found dead.
Gross Pathology: Twenty-five animals were examined. In all cases the animals either had a pale, mottled liver or were grossly normal.
Laboratory Results: Salmonella spp. (Group A to I positive) were isolated in mixed culture from some but not all cases.
Contributor's Diagnosis and Comments:
33735, unlabelled Liver, necrosis, diffuse, acute, severe with hepatomegaly and amphophilic intranuclear inclusion bodies. Stomach, intranuclear inclusion bodies, superficial epithelium, rare. Duodenum, intranuclear inclusion bodies, epithelial cells. Pancreas, intranuclear inclusion bodies, acinar cells, rare.
33733 Liver, necrosis, diffuse, acute, severe with hepatomegaly and amphophilic intranuclear inclusion bodies. Duodenum, intranuclear inclusion bodies, epithelial cells. Pancreas, intranuclear inclusion bodies, acinar cells, rare. Lung, normal.
33709 Liver, necrosis, diffuse, acute, severe with hepatomegaly and amphophilic intranuclear inclusion bodies. Intestine, intranuclear inclusion bodies, epithelial cells. Pancreas, intranuclear inclusion bodies, acinar cells, rare. Stomach, normal.
Of twenty-five animals euthanized or submitted dead for necropsy, twenty showed liver lesions; most had inclusions at other epithelial sites similar to the cases presented here. The degree of hepatic inflammation associated with the presence of intranuclear inclusions varied widely. Additional sites affected in other cases included gall bladder epithelium, oral epithelium, kidney tubular epithelium, esophageal epithelium, lung and salivary gland. Viral culture produced only contaminants. Adenovirus-like particles were observed in electron micrographs of liver tissue from several affected animals. A very similar outbreak among juvenile Rankin's dragon lizards (Pogona henrylawsoni) has been reported (Frye et al., 1994), characterized by hepatic necrosis with large, basophilic intranuclear inclusion bodies. Electron microscopy showed numerous intranuclear paracrystalline arrays of adenovirus-like particles. A similar adenovirus infection has been reported in a bearded dragon in New Zealand (Julian and Durham, 1990).
AFIP Diagnosis:
1. Liver: Necrosis, disseminated, with numerous basophilic intranuclear inclusion bodies, Inland Bearded Dragon (Acanthodraco vitticeps), reptile.
2. Stomach, duodenum, and pancreas, epithelial cells: Basophilic intranuclear inclusion bodies, small numbers.
Conference Note: Adenovirus, a double-stranded DNA virus, has been reported in numerous reptiles including Nile crocodiles, boa constrictors, rosy boas, rat snakes, Gaboon vipers, Savannah monitor lizards, Jackson's chameleon, and Rankin's dragon. All of these reptiles had intranuclear viral inclusions in the gastrointestinal tract and/or liver; most also had hepatic necrosis.
Adenovirus is established in some breeding groups of bearded dragons in the United States. Transmission studies have not been done; however, lizards hatched from eggs incubated apart from parents and having no contact with adult lizards after hatching have developed the disease. This suggests that vertical transmission occurs.
In a recent case report of adenovirus and dependovirus-like infection of bearded dragons, the ultrastructural characteristics of the reptilian adenovirus included the formation of paracrystalline arrays in the nucleus of infected cells. The viral particles were 60-66 nm in diameter, non-enveloped, and had electron-dense or electron-lucent cores.
Contributor: Division of Comparative Medicine, Department of Pathology, Johns Hopkins University, Baltimore, MD 21205.
References:
1. Frye, F.L, Munn, K.J., Gardner, M., Barten, S.L. and L. B. Hadfy (1994) Adenovirus-like hepatitis in a group of related Rankin's dragon lizards (Pogona henrylawsoni) Journal of Zoo and Wildlife Medicine 25 (1) 167-171.
2. Julian, A.F. and P.J.K. Durham. (1990) Adenoviral hepatitis in a female bearded dragon (Amphilbolurus barbatus). New Zealand Veterinary Journal 30: 59-60.
3. Jacobson ER, Kopit W, Kenedy FA, and Funk RS: Coinfection of a bearded dragon, Pogona vitticeps, with adenovirus- and dependovirus-like viruses. Vet Pathol 33:343-346, 1996.
