MAST CELL NEOPLASIA IN THE GREEN IGUANA, IGUANA IGUANA.

This case series is the first description of mast cell neoplasia in green iguanas, Iguana iguana. All iguanas were adults. Six were females, and four were males. Lesions were associated with the oral cavity in 3 of 10 cases, and on the head in 3 of 10 cases. Three of the cases had masses over the trunk; a single case had a lesion on a limb. Single masses were most common involving the face or oral cavity (6 of 10), whereas four cases with neoplasia distributed along the trunk had multiple masses. One case developed peripheral blood mastocytosis. In most neoplasms, cells contained metachromatic granules in toluidine blue-stained sections. Polymerase chain reaction identified no internal tandem duplication mutation in exon 11 of c-kit, but a mutation in exon 8 in a single case. Compared with other reptiles, green iguanas may be predisposed to development of mast cell neoplasia.

AIR SAC TREMATODES (CYCLOCOELIDAE STOSSICH, 1902) INFECTING BIRDS IN ZOOLOGICAL INSTITUTIONS IN THE UNITED STATES.

Air sac trematodes (Digenea: Cyclocoelidae) were detected in 23 avian species from eight aviaries in the United States. Most of the infected host species were passeriform birds, but a few species in other orders also were infected. Four species of adult flukes were encountered: Circumvitellatrema momota, Morishitium sp., Psophiatrema greineri, and Szidatitrema yamagutii. Findings from retrospective review of medical records, necropsy records, and author observations are presented. Potential terrestrial snail intermediate hosts were collected from three indoor aviaries. A high prevalence (47%) of larval trematode infections was demonstrated in one species of nonnative snail (Prosopeas achatinacea); one larva was isolated and matched to the adult species (C. momota) from birds using PCR. Problems with introducing potentially infected wild-caught birds into aviaries, and exchanging captive individuals between aviaries where they potentially may carry infections, are discussed.

Surgical Management of an Intrathoracic Branchial Cyst in a Yellow-crested Cockatoo (Cacatua sulphurea).

A 40-year-old, female lesser crested cockatoo (Cacatua sulphurea) was presented with a complaint of hyporexia and sudden onset of sneezing and wheezing. Physical examination revealed mild stertorous inhalation, and the apex of the heart was palpable caudoventral to the distal tip of the sternum. Projection radiographic images showed a soft tissue mass displacing the heart and the thoracic portion of the trachea. A subsequent computed tomography series revealed a single, large, and predominantly encapsulated soft-tissue mass. The mass was contained within the cranial thoracic region and occupied most of the anatomic location of the thoracic portion of the clavicular air sac, extending around a portion of the trachea. A surgical exploratory procedure was performed, with a thoracic inlet thoracotomy, and the mass was found to be cystic and deeply attached to surrounding tissues at its caudal-most aspect. Complete excision was not possible, and the mass was drained and an incomplete resection was accomplished with approximately one-half of the cystic structure removed and submitted for histopathology. The mass was found to be benign, epithelial-lined, dense, fibrous connective tissue that would be consistent with a branchial cyst.

Four cases of iridociliary tumors in domestic rabbits (Oryctolagus Cuniculus).

Spontaneously occurring ocular neoplasia is rarely reported in rabbits. This case series presents four cases of rabbits diagnosed with iridociliary tumors, which have not been previously reported in this species. Major pathological findings include epithelial tumors affecting the anterior uvea with variable pigmentation and basement membrane formation. Follow-up information was only available for two cases, but neither showed evidence of metastasis, suggesting that the prognosis for these tumors in rabbits, as in other species, may be very good.

Widespread recombination, reassortment, and transmission of unbalanced compound viral genotypes in natural arenavirus infections.

Arenaviruses are one of the largest families of human hemorrhagic fever viruses and are known to infect both mammals and snakes. Arenaviruses package a large (L) and small (S) genome segment in their virions. For segmented RNA viruses like these, novel genotypes can be generated through mutation, recombination, and reassortment. Although it is believed that an ancient recombination event led to the emergence of a new lineage of mammalian arenaviruses, neither recombination nor reassortment has been definitively documented in natural arenavirus infections. Here, we used metagenomic sequencing to survey the viral diversity present in captive arenavirus-infected snakes. From 48 infected animals, we determined the complete or near complete sequence of 210 genome segments that grouped into 23 L and 11 S genotypes. The majority of snakes were multiply infected, with up to 4 distinct S and 11 distinct L segment genotypes in individual animals. This S/L imbalance was typical: in all cases intrahost L segment genotypes outnumbered S genotypes, and a particular S segment genotype dominated in individual animals and at a population level. We corroborated sequencing results by qRT-PCR and virus isolation, and isolates replicated as ensembles in culture. Numerous instances of recombination and reassortment were detected, including recombinant segments with unusual organizations featuring 2 intergenic regions and superfluous content, which were capable of stable replication and transmission despite their atypical structures. Overall, this represents intrahost diversity of an extent and form that goes well beyond what has been observed for arenaviruses or for viruses in general. This diversity can be plausibly attributed to the captive intermingling of sub-clinically infected wild-caught snakes. Thus, beyond providing a unique opportunity to study arenavirus evolution and adaptation, these findings allow the investigation of unintended anthropogenic impacts on viral ecology, diversity, and disease potential.

Organ weights and histopathology of double-crested cormorants (Phalacrocorax auritus) dosed orally or dermally with artificially weathered Mississippi Canyon 252 crude oil.

A series of toxicity tests were conducted to assess the effects of low to moderate exposure to artificially weathered Deepwater Horizon Mississippi Canyon 252 crude oil on representative avian species as part of the Natural Resource Damage Assessment. The present report summarizes effects of oral exposure (n=26) of double-crested cormorants (DCCO; Phalacrocorax auritus) to 5 or 10ml oil kg-1 day-1 for up to 21 days or dermal application (n=25) of 13ml oil to breast and back feathers every three days totaling 6 applications in 21 days on organ weights and histopathology. Absolute and relative kidney and liver weights were increased in birds exposed to oil. Additionally, gross and/or histopathologic lesions occurred in the kidney, heart, pancreas and thyroid. Clinically significant renal lesions in the orally dosed birds included squamous metaplasia and increased epithelial hypertrophy of the collecting ducts and renal tubules and mineralization in comparison to controls. Gross cardiac lesions including thin walls and flaccid musculature were documented in both orally and dermally dosed birds and myocardial fibrosis was found in low numbers of dermally dosed birds only. Cytoplasmic vacuolation of the exocrine pancreas was noted in orally dosed birds only. Thyroid follicular hyperplasia was increased in dermally dosed birds only possibly due to increased metabolism required to compensate damaged feather integrity and thermoregulate. Gastrointestinal ulceration was found in orally dosed birds only. There were no significant hepatic histopathologic lesions induced by either exposure route. Therefore, hepatic histopathology is likely not a good representation of oil-induced damage. Taken together, the results suggest that oral or dermal exposure of DCCOs to artificially weathered MC252 crude oil induced organ damage that could potentially affect survivability.

Isolation of a Bohle-like iridovirus from boreal toads housed within a cosmopolitan aquarium collection.

A captive 'survival assurance' population of 56 endangered boreal toads Anaxyrus boreas boreas, housed within a cosmopolitan collection of amphibians originating from Southeast Asia and other locations, experienced high mortality (91%) in April to July 2010. Histological examination demonstrated lesions consistent with ranaviral disease, including multicentric necrosis of skin, kidney, liver, spleen, and hematopoietic tissue, vasculitis, and myriad basophilic intracytoplasmic inclusion bodies. Initial confirmation of ranavirus infection was made by Taqman real-time PCR analysis of a portion of the major capsid protein (MCP) gene and detection of iridovirus-like particles by transmission electron microscopy. Preliminary DNA sequence analysis of the MCP, DNA polymerase, and neurofilament protein (NFP) genes demonstrated highest identity with Bohle iridovirus (BIV). A virus, tentatively designated zoo ranavirus (ZRV), was subsequently isolated, and viral protein profiles, restriction fragment length polymorphism analysis, and next generation DNA sequencing were performed. Comparison of a concatenated set of 4 ZRV genes, for which BIV sequence data are available, with sequence data from representative ranaviruses confirmed that ZRV was most similar to BIV. This is the first report of a BIV-like agent outside of Australia. However, it is not clear whether ZRV is a novel North American variant of BIV or whether it was acquired by exposure to amphibians co-inhabiting the same facility and originating from different geographic locations. Lastly, several surviving toads remained PCR-positive 10 wk after the conclusion of the outbreak. This finding has implications for the management of amphibians destined for use in reintroduction programs, as their release may inadvertently lead to viral dissemination.

Gastrointestinal cryptosporidiosis in captive psittacine birds in the United States: a case review.

Histopathologic analysis performed on tissue samples from 34 captive psittacine birds over a 14-year period demonstrated gastrointestinal cryptosporidiosis. Although 8 birds had died unexpectedly, at least 10 showed gastrointestinal signs before death. Most birds had other significant pathologic lesions, unrelated to cryptosporidiosis, in which case Cryptosporidium was likely a secondary pathogen. However, in 11 birds the only significant histopathologic finding was gastrointestinal cryptosporidiosis. In 2 lovebird (Agapornis species) cases, direct sequencing of proventricular samples confirmed the presence of Cryptosporidium avian genotype III. A description and analysis of the pathologic findings in these 34 birds, as well as a review of avian gastrointestinal cryptosporidiosis, is provided.

Diseases of domestic rabbits by purpose; a retrospective study of 2,583 cases received at 4 diagnostic laboratories in California, USA, 2013-2022.

Domestic rabbits (Oryctolagus cuniculus) are commonly kept as pets or bred for laboratory investigation, meat, fur production, or a combination of these purposes. We conducted a retrospective study to assess the prevalence of diseases in domestic rabbits according to purpose. We retrieved results of autopsies, biopsies, and cytologies from 2,583 cases received at 4 diagnostic laboratories in California from 2013-2022. Rabbits were classified as pets (2,241; 86.8%), laboratory animals (92; 3.6%), meat-production animals (60; 2.3%), or multipurpose animals (190; 7.4%). A final diagnosis was reached in 2,360 (91.4%) cases and was classified by system, etiology, and type of process. Pet rabbits had the highest median age (5.9 y; vs. 3 y, 0.67 y, and 0.25 y in meat, multipurpose, and laboratory rabbits, respectively), and most of the neoplasms were diagnosed in this group (872 of the total 896 neoplasms in the study; 97.3%), with tumors of the skin, female reproductive tract, and hematolymphoid system being the most common. Laboratory rabbits had a high prevalence of infectious enterotyphlocolitis (40 of 92; 43.4%), and ~45% of those cases were due to opportunistic colibacillosis. Infectious and parasitic pneumonias were common in meat rabbits (18 of 60; 30%); pneumonic pasteurellosis accounted for >60% of those cases. Infectious cholangiohepatitides were common in multipurpose rabbits (61 of 110; 55.5%), with rabbit hemorrhagic disease representing the most common etiology (82.4% of those cases). Our results demonstrate that purpose of use can predict prevalence of disease in rabbits submitted to diagnostic laboratories.

Hepatic copper accumulates in ferrets with and without hepatobiliary disease.

OBJECTIVE: To determine hepatic copper concentrations and zonal distribution in ferrets with and without hepatobiliary disease, validate rhodanine-based qualitative copper scoring and digital copper quantification in ferret hepatic samples, and ascertain whether clinical features predicted copper accumulation. ANIMALS: 34 ferrets, including 7 with necroinflammatory disease, 5 with hepatocellular carcinoma, 13 with non-necroinflammatory disease, and 9 with no hepatobiliary disease. PROCEDURES: Rhodanine-based digital copper quantification was validated by use of liver dually measured by atomic absorption spectroscopy and digital scanning (R2 = 0.98). Clinical features and hepatic copper scores and concentrations (dry weight liver) were compared between groups. Zonal copper distribution was determined. RESULTS: Hepatic copper concentration was strongly correlated with copper scores (ρ = 0.88). Ferrets with hepatobiliary disease were significantly older and had significantly higher serum alkaline phosphatase and γ-glutamyltransferase activities and creatinine concentrations. Centrilobular copper accumulated in 23 of 34 (64%) ferrets with (n = 15) and without (8) hepatobiliary disease. Median copper concentrations were not significantly different between ferrets with and without hepatobiliary disease but were significantly higher within neoplastic hepatic tissue in ferrets with hepatocellular carcinoma. Hepatic copper concentrations exceeded feline (> 180 µg/g) and canine (> 400 µg/g) reference limits in 19 and 9 ferrets, respectively. Hepatic copper > 1,000 µg/g occurred in 5 ferrets with and 2 without hepatobiliary disease. Clinical features did not predict copper accumulation. CLINICAL RELEVANCE: Rhodanine-based digital copper quantification and qualitative copper scoring discerned liver copper accumulation in ferrets. Ferrets with and without hepatobiliary disease displayed a propensity for centrilobular hepatic copper accumulation of uncertain clinical importance. Clinical and clinicopathologic features could not exclusively implicate pathologic copper accumulation.

Clinical, surgical, and pathological findings in client-owned rabbits with histologically confirmed appendicitis: 19 cases (2015-2019).

OBJECTIVE: To report clinical, surgical, and pathological findings in client-owned rabbits with histologically confirmed appendicitis. ANIMALS: 19 rabbits. PROCEDURES: Medical records for client-owned rabbits that had a histologic diagnosis of appendicitis were reviewed. RESULTS: Median age of the rabbits at presentation was 24.0 months (range, 4 to 84 months). Seventeen cases occurred during the summer and fall seasons. Decreased appetite (17/19 rabbits), abnormal rectal temperature (hyperthermia, 9/16 rabbits; hypothermia, 4/16 rabbits), hypocalcemia (8/11 rabbits), and hypoglycemia (7/15 rabbits) were common signs. Abdominal ultrasonography and CT findings were suggestive of appendicitis in 6 of 8 rabbits and in 1 of 2 rabbits, respectively. Of the 6 rabbits that received medical treatment, 3 died at 48 hours, 1 died at 24 hours after hospitalization, and 1 died at 10 days after presentation; 1 rabbit was alive at 1,030 days after presentation. Of the 8 rabbits that underwent appendectomy, 3 died before discharge from the hospital and 1 died 113 days after surgery; 4 rabbits were alive at 315, 334, 1,433, and 1,473 days after presentation. The remaining 5 rabbits either died or were euthanized before treatment could be instituted. In each of the 19 rabbits, the appendix had evidence of severe inflammation with mucosal ulceration, heterophilic inflammation, and necrotic debris. CLINICAL RELEVANCE: For rabbits with decreased appetite and an apparently painful abdomen, hyperthermia, hypocalcemia, or hypoglycemia, appendicitis should be considered as a differential diagnosis. Further comparisons of medical and surgical treatments are required to establish treatment recommendations for rabbits with appendicitis.

Cryptosporidium avian genotype III as a possible causative agent of chronic vomiting in peach-faced lovebirds (Agapornis roseicollis).

In the present study, Cryptosporidium oocysts were found, by light microscopy, in 37 fecal samples of peach-faced lovebirds (Agapornis roseicollis). Cryptosporidium avian genotype III was isolated in 13 of the 37 infected birds by sequence analysis of the small subunit ribosomal RNA and the actin genes. All of the birds showed chronic vomiting and weight loss with enlargement of isthmi, narrowed proventricular lumens, and thickened proventricular walls radiographically. Cryptosporidium parasites were found only in the ductal epithelium of the proventricular glands in three of the tissue samples provided for necropsy. To date, there have been no reports concerning the pathogenicity, nor the location, of avian genotype III in avian hosts. Our report confirms, for the first time, the presence of avian genotype III in peach-faced lovebirds in Japan and also reveals the location in the avian host.

Disease Overview of the Urinary Tract in Exotic Companion Mammals and Tips on Clinical Management.

Diseases of the urinary tract are reviewed, covering infectious (bacterial, viral, parasitic), degenerative, congenital, metabolic, nutritional, neoplastic, obstructive, and toxic causes. Some clinical presentations and diagnostic procedures are described for ferrets, rabbits, guinea pigs, hamsters, mice, rats, chinchillas, hedgehogs, and sugar gliders, as well as therapies.

Pathology of Diseases of Geriatric Exotic Mammals.

The review covers select disease conditions most frequently described in aging rodents (rats, mice, hamsters, guinea pigs), rabbits, and ferrets. The conditions are categorized by general organ systems, infectious diseases, and neoplasms. Two data systems, the Veterinary Medical Teaching Hospital and Comparative Pathology Laboratory at the University of California, Davis and Zoo/Exotic Pathology Service, Citrus Heights, California were used in the determining disease conditions to describe.

Development and validation of 2 probe-hybridization quantitative PCR assays for rapid detection of a pathogenic Coxiella species in captive psittacines.

Avian coxiellosis is an emerging cause of morbidity and mortality among captive psittacines, and the utility of a rapid detection test using easily obtained samples is paramount in a clinical setting. New sequences were obtained from 3 genes: groEL, dnaK, and rpoB. We developed probe-hybridization quantitative PCR (qPCR) assays using groEL and dnaK genes. Samples, including splenic aspirates, liver aspirates, whole blood, and choanal, conjunctival, and cloacal swabs, were collected from 4 psittacine species including 3 blue-and-gold macaws (Ara ararauna), 2 scarlet-chested parrots (Neophema splendida), 1 Timneh African grey parrot (Psittacus timneh), and 1 yellow-naped Amazon parrot (Amazona auropalliata). Retrospective review of postmortem findings from 3 of these psittacines included splenomegaly, hepatitis, and/or transmission electron microscopy confirmation consistent with previous reports of avian coxiellosis. There was 100% agreement between these assays and consensus PCR with sequencing. A Wilcoxon rank-sum test found a strong correlation between groEL and dnaK cycle threshold values (p < 0.001), validating these assays for detection of this avian Coxiella sp.

Mandibular squamous cell carcinoma in 2 psittacines.

A unilateral, malformed gnathotheca in a green-winged macaw (Ara chloropterus) was managed for 16 mo with periodic beak trims. Biopsy of the affected beak did not identify an underlying cause; however, at postmortem examination, a densely cellular neoplasm invaded the mandible from the beak, dissecting and effacing the cortex and trabecular bone and inciting periosteal proliferation. There was no evidence of metastasis. Neoplastic cells were strongly immunopositive for cytokeratin AE1/AE3, consistent with squamous cell carcinoma (SCC). A black-headed caique (Pionites melanocephalus) was presented with a similar clinical history, timeline, and gross appearance. Biopsy of the mandibular portion of the lesion resulted in a diagnosis of SCC. Medical management with toceranib at a palliative dose resulted in adverse side effects and was discontinued. Early diagnosis of mandibular SCC may allow for early intervention and development of treatment modalities. Our 2 cases suggest that the mandibular bone, not the beak, may be a preferred biopsy site in the diagnosis of mandibular SCC in psittacines.

Proliferative endometrial lesions in a group of Seba's short-tailed bats (Carollia perspicillata).

An unusually high prevalence of uterine changes was observed on necropsy in a group of 169 female Seba's short-tailed bats (Carollia perspicillata). In this case study, 27 animals were affected from 1997 to 2007, representing 16% of the group population. All bats were of an indeterminate age and originated from the same facility, but were housed in three different zoological institutions. Deaths occurred year round. Most animals were found dead, with no previous clinical signs. Clinical signs, when present, included a markedly distended abdomen, extended periods of time perched on the exhibit floor, lethargy, and anorexia. Histologic changes included florid segmental to diffuse endometrial hyperplasia and occasional hemorrhage and adenomyosis. The cause for this condition has not been determined.

Echinococcus oligarthrus cystic hydatidosis in Brazilian agouti (Dasyprocta leporina).

Echinococcus oligarthrus hydatid cyst disease was diagnosed in two imported wild-caught Brazilian agouti (Dasyprocta leporina). The cysts were found incidentally during routine examinations and never appeared to cause any apparent clinical signs. Identification of the cysts was confirmed via histopathology. Over a period of 2 yr, the cysts calcified but did not reabsorb. Treatment with praziquantal and albendazole did not appear to affect the cysts. Agoutis are intermediate hosts of E. oligarthrus in the wild, where jaguars (Panthera onca) and pumas (Puma concolor) act as definitive hosts. Caution is advised when working with E. oligarthrus-infected animals because of the zoonotic disease potential.

Treatment of nonepitheliotropic cutaneous B-cell lymphoma in an umbrella cockatoo (Cacatua alba).

A 3.5-year-old umbrella cockatoo (Cacatua alba) was presented because of the development of widely disseminated subcutaneous nodules. The diagnostic work-up included a complete blood count, plasma biochemical analysis, and whole body radiographs. Biopsy samples of the skin lesions were submitted for histopathologic evaluation, bacterial culture and sensitivity testing, immunohistochemistry staining, and acid-fast staining. The diagnosis was nonepitheliotropic cutaneous B-cell lymphoma with a leukemic blood picture. The bird was treated with a chemotherapeutic regimen consisting of vincristine and chlorambucil for 17 weeks. During treatment, the complete blood count was monitored every 1-3 weeks, and the plasma biochemical analysis was monitored every 3-4 weeks. The bird was in partial remission on week 9. On week 17, the bird became acutely ill and was fluffed, depressed, anorectic, and anemic. The chemotherapeutic regimen was discontinued. At this time, the bird had a consistent lymphocytosis but no neoplastic lymphocytes were seen in the general circulation. At week 29 the bird was in complete remission and remains in complete remission 8 years after chemotherapy was discontinued.

The avian thyroid gland.

There has been a considerable amount of research regarding the function of the avian thyroid gland, particularly in chickens. There is also more information on diseases of the avian thyroid gland, although it is usually in the form of case reports. This article covers a limited amount of material on the structure and function of the avian thyroid gland and its diseases.