A mystery revealed: an update on eosinophil and other blood cell morphology of the Argentine black and white tegu (Salvator merianae).

Reptile white blood cell (WBC) morphological features are strikingly variable across species. In the Argentine black and white tegu (Salvator merianae), red tegu (Salvator rufescens), and Savannah monitor (Varanus exanthematicus), previous reports described a WBC type with a single distinct, clear, linear- to ovoid- to crescent-shaped inclusion of presumptive monocytic origin. The objective of this study was to further investigate the origin of this unique WBC type with crescent-shaped inclusions. Blood samples from two Argentine black and white tegus, tegu 1, a 4-year-old female, and tegu 2, a 2-year-old presumed male, were submitted for routine hematological evaluation. Additional blood films were prepared and stained with these cytochemical stains: alkaline phosphatase (ALP; naphthol AS-MX phosphate substrate), alpha-naphthyl butyrate esterase, alpha-chloroacetate esterase, myeloperoxidase, Periodic acid-Schiff, and Sudan black B. Blood films from tegu 1 were also stained with a second ALP stain (5-bromo-4-chloro-3-indoxyl-phosphate and nitroblue tetrazolium substrate), Luna, luxol fast blue, and toluidine blue. The blood from tegu 1 was cytocentrifuged to isolate and fix the buffy coat in glutaraldehyde 2.5% aqueous solution for transmission electron microscopy. Six morphologically distinct WBC types were identified from tegu 1, including heterophils, basophils, monocytes, azurophils, lymphocytes, and the unique WBC type, which were identified as eosinophils with inclusions. WBC types in tegu 2 were similar; however, eosinophils lacked a discernable inclusion. Proper WBC identification will be useful in obtaining accurate hemogram data for this species.

Guidelines for resident training in veterinary clinical pathology. IV: Laboratory quality management-Teaching domains, competencies, and suggested learning outcomes.

BACKGROUND: The 2019 ASVCP Education Committee Forum for Discussion, presented at the annual ASVCP/ACVP meeting, identified a need to develop recommendations for teaching laboratory quality management principles in veterinary clinical pathology residency training programs. OBJECTIVES: To present a competency-based framework for teaching laboratory quality management principles in veterinary clinical pathology residency training programs, including entrustable professional activities (EPAs), domains of competence, individual competencies, and learning outcomes. METHODS: A joint subcommittee of the ASVCP Quality Assurance and Laboratory Standards (QALS) and Education Committees executed this project. A draft guideline version was reviewed by the ASVCP membership and shared with selected ACVP committees in early 2022, and a final version was voted upon by the full QALS and Education Committees in late 2022. RESULTS: Eleven domains of competence with relevant individual competencies were identified. In addition, suggested learning outcomes and resource lists were developed. Domains and individual competencies were mapped to six EPAs. CONCLUSIONS: This guideline presents a framework for teaching principles of laboratory quality management in veterinary clinical pathology residency training programs and was designed to be comprehensive yet practical. Guidance on pedagogical terms and possible routes of implementation are included. Recommendations herein aim to improve and support resident training but may require gradual implementation, as programs phase in necessary expertise and resources. Future directions include the development of learning milestones and assessments and consideration of how recommendations intersect with the American College of Veterinary Pathologists training program accreditation and certifying examination.

Left shift and toxic change in heterophils and neutrophils of non-mammalian vertebrates: A comparative review, image atlas, and practical considerations.

Heterophils and neutrophils are important first cellular responders to inflammatory conditions. In addition to quantitative shifts in the numbers of these cells in blood, inflammatory disease states often have accompanying increases in immature precursor stages (left shift) and/or evidence of toxic change on blood film evaluation. Recognition of left shift and toxic change morphologies is a salient diagnostic finding with clinical relevance across species. The objectives of this report are to (a) review heterophil and neutrophil function and structure across the vertebrate animal kingdom, (b) compare morphologic features of left shift and toxic change in heterophils and neutrophils of non-mammalian vertebrates (NMV) to mammals, (c) provide an image guide demonstrating the breadth of morphologic diversity of heterophil and neutrophil lineages in health and disease across taxa, and (d) discuss practical considerations for clinical pathologists and other professionals involved in the recognition and interpretation of observations in the inflammatory leukogram of NMV.

Fatal Hymenolepis nana cestodiasis in a ring-tailed lemur (Lemur catta).

The cestode Hymenolepis nana is a common parasite of humans and mice. Fecal shedding in the absence of clinical disease has previously been reported in ring-tailed lemurs (Lemur catta). This report describes fatal, disseminated H. nana cestodiasis infection in an aged ring-tailed lemur in a zoological collection. The parasites were associated with severe multifocal to coalescing and regionally extensive pyogranulomatous hepatitis and moderate multifocal pneumonia. The morphology of the parasites was highly unusual. Profiles were variably sized, ellipsoid to irregularly serpiginous, lined by a thin tegument, and filled with lightly eosinophilic fibrillar stroma and numerous, round basophilic cells. Polymerase chain reaction targeting a portion of the 18S rRNA gene and DNA sequencing of the amplicon showed 100% homology with H. nana.

Reproductive tract neoplasia in adult female Asian elephants (Elephas maximus).

Recent reports have highlighted a lower-than-expected prevalence of neoplasia in elephants and suggested mechanisms for cancer resistance. But despite infrequent reports in the literature, uterine neoplasia is common in managed Asian elephants (Elephas maximus). This study is an archival review of reproductive tract neoplasia in 80 adult female Asian elephant mortalities in managed care facilities in the United States from 1988 to 2019. Neoplasms occurred in 64/80 (80%) of cases. Most were in the uterus (63/64; 98%) with only a single case of ovarian neoplasia. Myometrial leiomyomas were present in 57/63 (90%) cases with uterine neoplasia. Uterine adenocarcinoma was present in 8/63 (13%) cases. Remaining cases included endometrial adenoma (2), focal carcinoma in situ in endometrial polyps (1), anaplastic carcinoma (1), endometrial hemangioma (1), primitive neuroectodermal tumor (PNET; 1), and angiosarcoma (1). One case with uterine adenocarcinoma had a separate pelvic mass histologically characterized as an anaplastic sarcoma. Distant metastases were documented in 5/8 (63%) cases of uterine adenocarcinoma, and in the uterine anaplastic carcinoma, PNET, and angiosarcoma. Four uterine adenocarcinomas and one carcinoma in situ were examined immunohistochemically for pan-cytokeratin, vimentin, and estrogen receptor. In all, neoplastic cells were pan-cytokeratin positive and vimentin negative, and in 2 cases were immunoreactive for estrogen receptor. Results show that female reproductive tract neoplasia, particularly of the uterus, is common in Asian elephants and is not limited to leiomyomas. Importantly, uterine neoplasms have the potential to impact fecundity and may represent obstacles to conservation in managed care.

SARCOCYSTOSIS IN A CAPTIVE FLOCK OF THICK-BILLED PARROTS (RHYNCHOPSITTA PACHYRHYNCHA) FROM 2005 TO 2016: MORBIDITY, MORTALITY, DIAGNOSTICS, AND MANAGEMENT STRATEGIES.

Sarcocystosis was diagnosed in a captive flock of thick-billed parrots (Rhynchopsitta pachyrhyncha) at the Wildlife Conservation Society's Queens Zoo. Since the index case in 2005, 45% of mortalities in birds over 30 days of age were due to sarcocystosis. Sarcocystis falcatula was repeatedly identified as the causative agent. The disease predominantly affected younger adult parrots. Administration of antiparasitic medications prior to development of respiratory signs prolonged life in infected birds, but disease was fatal until utilization of a three-drug combination (pyrimethamine, trimethoprim-sulfamethoxazole, and ponazuril). This protocol may require in excess of 6 mo of therapy to achieve clinical resolution of active disease. Plasma creatine kinase activity was found to be the most useful test in diagnosing infection and monitoring response to therapy. Polymerase chain reaction (PCR) for apicomplexan organisms on antemortem whole blood, blood smears, or dried blood spots helped confirm suspected cases, but due to the poor sensitivity was sometimes misleading when assessing response to therapy or resolution of clinical disease. Preventive measures, focusing on exclusion and removal of Virginia opossums (Didelphis virginiana) from zoo grounds failed to curtail the occurrence of sarcocystosis in the flock. Other preventative steps, such as modification of feeding stations to exclude potential arthropod paratenic hosts and prophylaxis trials with diclazuril, appeared to successfully mitigate new infections. Given the diagnostic and therapeutic challenges, prevention of exposure to S. falcatula is essential to ex-situ conservation efforts for thick-billed parrots.

DIFFUSIBLE IODINE-BASED CONTRAST-ENHANCED COMPUTED TOMOGRAPHY AS A NECROPSY AID: A CASE REPORT EVALUATING RESPIRATORY DISEASE IN MACROCEPHALON MALEO.

This study describes the novel use of diffusible iodine-based contrast-enhanced computed tomography (diceCT) as a digital necropsy aid. DiceCT was used postmortem to evaluate the cause of progressive respiratory disease in a juvenile maleo (Macrocephalon maleo). The technique facilitated soft-tissue contrast and a three-dimensional investigation of sinus and choanal anatomy as a means to identify normal and pathologic morphologies. Results showed right-sided narial occlusion by mucoid debris, along with left-sided choanal stenosis caused by osteomyelitis and reactive bone formation. The high spatial resolution afforded by diceCT enabled targeted histology and quantification of the clinical impact of pathologies, which contributed to an effective 60% loss in nasal airway aperture for this individual. This study demonstrates how adding diceCT to traditional necropsy can proffer additional understanding of an individual's pathology, and the resulting data can enhance research programs in vertebrate anatomy, evolution, and health.

Outbreak of Peste des Petits Ruminants among Critically Endangered Mongolian Saiga and Other Wild Ungulates, Mongolia, 2016-2017.

The 2016-2017 introduction of peste des petits ruminants virus (PPRV) into livestock in Mongolia was followed by mass mortality of the critically endangered Mongolian saiga antelope and other rare wild ungulates. To assess the nature and population effects of this outbreak among wild ungulates, we collected clinical, histopathologic, epidemiologic, and ecological evidence. Molecular characterization confirmed that the causative agent was PPRV lineage IV. The spatiotemporal patterns of cases among wildlife were similar to those among livestock affected by the PPRV outbreak, suggesting spillover of virus from livestock at multiple locations and time points and subsequent spread among wild ungulates. Estimates of saiga abundance suggested a population decline of 80%, raising substantial concerns for the species' survival. Consideration of the entire ungulate community (wild and domestic) is essential for elucidating the epidemiology of PPRV in Mongolia, addressing the threats to wild ungulate conservation, and achieving global PPRV eradication.

STANDING COMPUTED TOMOGRAPHY IN NONANESTHETIZED LITTLE PENGUINS (EUDYPTULA MINOR) TO ASSESS RESPIRATORY SYSTEM ANATOMY AND MONITOR DISEASE.

Multidetector computed tomography (MDCT) scans were performed in clinically healthy, nonanesthetized, standing little penguins (Eudyptula minor) to determine reference ranges for air-sac and lung volumes, as well as lung density. Five of 15 clinically healthy birds were diagnosed with pulmonary granulomas on initial MDCT scans. Granulomas were not readily apparent on radiographs, even in cases where the entire normal pulmonary parenchymal architecture was effaced on the MDCT scan. Serial MDCT scans after antifungal and antimycobacterial therapies demonstrated a response to treatment. MDCT scanning in nonanesthetized little penguins proved to be a well-tolerated, non-invasive imaging modality for respiratory diseases that are otherwise difficult to diagnose, including aspergillosis and mycobacteriosis.

DIAGNOSIS AND MANAGEMENT OF MYCOBACTERIOSIS IN A COLONY OF LITTLE PENGUINS (EUDYPTULA MINOR).

A group of zoo-housed little penguins (Eudyptula minor) was diagnosed with mycobacteriosis. While undergoing multidetector computed tomography (MDCT) imaging for an unrelated research project, pulmonary lesions were detected in multiple individuals. In general, birds appeared healthy and free of outward signs of disease. After the loss of three individuals, polyclonal mycobacterial disease due to Mycobacterium avium-intracellulare complex was confirmed. Surviving birds were treated with rifampin (45 mg/kg), ethambutol (30 mg/kg), clarithromycin (10 mg/kg), and enrofloxacin (30 mg/kg) compounded into a single capsule administered once a day in food. After 3 mo of therapy, MDCT imaging documented a decrease in nodule size and number in all remaining birds, with further improvement documented after 13 mo of treatment. MDCT imaging was invaluable for diagnosing disease, documenting disease progression over time, and assessing response to therapy. Early initiation of therapy before the development of outward signs of disease led to resolution of mycobacterial pulmonary lesions in multiple penguins. Mycobacterial disease in this group of little penguins, as well as previously published reports, suggests that the species is at increased risk for developing mycobacteriosis.

Embolic mycotic encephalitis in a cow following Mortierella wolfii infection of a surgery site.

A 5-y-old Holstein dairy cow had surgery for a suspected displaced abomasum 10 d postpartum, developed acute neurologic signs at day 19, and was found dead 21 d postpartum. At autopsy, there was a peri-incisional intramuscular abscess that communicated with the peritoneal cavity, as well as hemorrhage and malacia involving the brain, and multiple nodules in the liver, kidneys, and lungs. Fungal hyphae were seen histologically at the surgery site, on the surface of the liver, and in lesions of severe necrotizing vasculitis in the lungs, kidneys, brain, and liver. The uterus was free of fungal organisms. Pan-fungal PCR and DNA sequencing identified the fungus as Mortierella wolfii. Previously reported deaths from M. wolfii have been related to abortion, but in this case, there was no histologic evidence of fungal organisms in the uterus, calving was routine, and there was a several week delay between calving and development of neurologic signs. The findings suggested a unique case of surgical site infection with subsequent embolic mycosis.

Avian Hemosporidian Parasite Lineages in Four Species of Free-ranging Migratory Waterbirds from Mongolia, 2008.

Avian hemosporidian parasites have been detected in Asia, but little information is known about the hemosporidian parasite lineages that circulate in waterbirds that migrate along the East Asian and Central Asian migratory flyways to breed in Mongolia. To gather baseline data on hemosporidian parasite presence in Mongolian waterbirds, 151 blood-spot samples (81 hatch year [HY] and 70 after hatch year [AHY]) from Bar-headed Goose (Anser indicus), Ruddy Shelduck (Tadorna ferruginea), Great Cormorant ( Phalacrocorax carbo ), and Mongolian Gull (Larus mongolicus) were screened for three genera of apicomplexan parasites, Plasmodium, Haemoproteus, and Leucocytozoon, using nested PCR. Of these, 17 samples (11%, 95% confidence interval: 7.1-17.4%), representing all four species, were positive. We identified 10 species (six Plasmodium, one Haemoproteus, and three Leucocytozoon) through mitochondrial DNA sequencing of the cytochrome b gene and BLAST analysis. One lineage shared 100% nucleotide identity to a hemosporidian parasite lineage that has been previously identified as Plasmodium relictum (SGS1). Six lineages were found in AHY birds and five in HY birds, the latter confirming that infection with some of the identified hemosporidian parasites occurred on the breeding grounds. Our data provide important baseline information on hemosporidian parasite lineages found in AHY waterbirds that breed and migrate through Mongolia as well as in HY offspring.

Pigs in Toxicology: Breed Differences in Metabolism and Background Findings.

Both a rodent and a nonrodent species are required for evaluation in nonclinical safety studies conducted to support human clinical trials. Historically, dogs and nonhuman primates have been the nonrodent species of choice. Swine, especially the miniature swine or minipigs, are increasingly being used in preclinical safety as an alternate nonrodent species. The pig is an appropriate option for these toxicology studies based on metabolic pathways utilized in xenobiotic biotransformation. Both similarities and differences exist in phase I and phase II biotransformation pathways between humans and pigs. There are numerous breeds of pigs, yet only a few of these breeds are characterized with regard to both xenobiotic-metabolizing enzymes and background pathology findings. Some specific differences in these enzymes based on breed and sex are known. Although swine have been used extensively in biomedical research, there is also a paucity of information in the current literature detailing the incidence of background lesions and differences between commonly used breeds. Here, the xenobiotic-metabolizing enzymes are compared between humans and pigs, and minipig background pathology changes are reviewed with emphasis on breed differences.

Herd outbreak of bovine tuberculosis illustrates that route of infection correlates with anatomic distribution of lesions in cattle and cats.

An outbreak of bovine tuberculosis (TB) in a Michigan dairy herd resulted in quarantine, depopulation, pathology, and epidemiologic investigations. This herd, compared to other TB-infected herds in Michigan, was unusual in the long-term feeding of waste milk to its replacement calves. The herd had 80 cattle with positive results on caudal fold test or gamma interferon testing, which were reclassified as suspects because the herd had never been known to be tuberculous previously. Autopsy revealed striking variation in the anatomic distribution of gross anatomic lesions, microscopic lesions, and culture-positive lymph nodes between the adult cattle, the calves, and the domestic cats present on the farm. Adult cattle had lesions and culture-positive lymph nodes predominantly within the thoracic lymph nodes, whereas cats had 50% of their lesions and culture-positive lymph nodes in their abdomens, and 50% of positive calves had culture-positive lymph nodes in their abdomens. This difference in anatomic distribution correlated with the likely routes of infection, which are believed to be by direct airborne transmission in adult cattle and indirect ingestion of contaminated milk in both calves and cats. Although TB literature over the past 100-plus years states that the route of infection may manifest itself in differences in lesion anatomic distribution, our team has been working with TB for over 20 years, and we have never encountered such striking variation between different groups of animals on the same farm.

Background Pathological Changes in Minipigs: A Comparison of the Incidence and Nature among Different Breeds and Populations of Minipigs.

Swine, especially the miniature swine or minipigs, are increasingly being used in preclinical safety assessment of small molecules, biopharmaceutical agents, and medical devices as an alternate nonrodent species. Although swine have been used extensively in biomedical research, there is a paucity of information in the current literature detailing the incidence of background lesions and differences in incidence between commonly used breeds. This article is a collaborative effort between multiple organizations to define and document lesions found in the common breeds of minipigs used for toxicological risk assessment in North America (NA) and the European Union (EU). We retrospectively assessed 10 years of historical control data from several institutions located in NA and EU, covering the period of 2004-2015. Here we report the background lesions with consideration of breed and geographical location. To our knowledge, this is the first report documenting spontaneous background lesions in commonly used breeds of swine in both NA and EU. This report serves as a resource to pathologists and will aid in interpretation of findings and differentiation of background from test article-related changes.

Prevalence and underlying causes of histologic abnormalities in cats suspected to have chronic small bowel disease: 300 cases (2008-2013).

OBJECTIVE: To determine prevalence of histologic abnormalities in cats suspected, on the basis of compatible clinical signs and ultrasonographic findings, to have chronic small bowel disease; identify the most common underlying causes in affected cats; and compare methods for differentiating among the various causes of chronic small bowel disease. DESIGN: Retrospective case series. ANIMALS: 300 client-owned domestic cats suspected to have chronic small bowel disease. PROCEDURES: Medical records were reviewed to identify cats evaluated because of chronic vomiting, chronic small bowel diarrhea, or weight loss that also had ultrasonographic evidence of thickening of the small intestine. Cats were included in the study if full-thickness biopsy specimens had been obtained from ≥ 3 locations of the small intestine by means of laparotomy and biopsy specimens had been examined by means of histologic evaluation and, when necessary to obtain a diagnosis, immunohistochemical analysis and a PCR assay for antigen receptor rearrangement. RESULTS: Chronic small bowel disease was diagnosed in 288 of the 300 (96%) cats. The most common diagnoses were chronic enteritis (n = 150) and intestinal lymphoma (124). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that a high percentage of cats with clinical signs of chronic small bowel disease and ultrasonographic evidence of thickening of the small intestine had histologic abnormalities. Furthermore, full-thickness biopsy specimens were useful in differentiating between intestinal lymphoma and chronic enteritis, but such differentiation was not possible with ultrasonography or clinicopathologic testing alone.

T-CELL LYMPHOCYTIC LEUKEMIA IN A FALLOW DEER (DAMA DAMA).

A 17-yr-old female fallow deer presented with ataxia, inappetence, decreased fecal output, and decreased mentation. A complete blood count demonstrated leukocytosis (24.1×10(3)/µl, n=1.16-7.38×10(3)/µl), characterized by lymphocytosis (22.89×10(3)/µl, n=0.18-3.65×10(3)/µl), anemia (packed cell volume 20%, n=29.0-55.8%), decreased red blood cell count (4.1×10(3)/µl, n=6.86-14.72×10(3)/µl), and decreased hemoglobin (7.5 g/dl, n=9.4-19.2 g/dl). Numerous mature, well-differentiated lymphocytes were noted on the blood film. Despite treatment and clinical improvement, the decision was made to euthanize the deer. Histopathology identified a monomorphic population of CD3 positive, CD79a negative small lymphocytes replacing most of the hematopoietic tissue in the bone marrow without evidence of tissue invasion. Results of viral screening were negative.

Imaging diagnosis--computed tomographic, surgical, and histopathologic characteristics of an infiltrative angiolipoma in a dog.

A 6-year-old female spayed Shetland Sheepdog presented for evaluation of a subcutaneous mass over the right prescapular region. The mass had been cytologically diagnosed as a lipoma by the referring veterinarian 20 months prior, but had grown significantly and was very firm. CT scan of the mass was suggestive of neoplasia; however, the tissue of origin could not be determined. Histopathologic evaluation diagnosed infiltrative angiolipoma, and marginal resection of the tumor was performed. Infiltrative angiolipomas are benign but locally aggressive neoplasms uncommonly reported in veterinary medicine. This report correlates the clinical, CT, and histopathologic characteristics of an infiltrative angiolipoma.