Hepatic lipid accumulation is associated with multiple metabolic pathway alterations but not dyslipidemia and insulin resistance in central bearded dragons (Pogona vitticeps)

OBJECTIVE

To investigate associations between hepatic fat accumulation, fibrosis, and plasma values of primary metabolites, biochemical measurands, insulin, and lipoproteins in bearded dragons.

ANIMALS

48 adult central bearded dragons (Pogona vitticeps).

METHODS

Dragons were sedated with alfaxalone, and a blood sample was collected. Plasma was submitted for untargeted primary metabolomics using gas chromatography time-of-flight mass spectrometry, a biochemistry panel, and a lipoprotein panel determined by PAGE. Hepatic lipid content was quantified by liver attenuation measurements from CT images and digital image analysis of standardized histologic sections of the liver. Fibrosis was quantified by digital image analysis on Masson's trichrome-stained histologic sections. Severity was determined from pathologic review of liver sections according to a standardized grading system. Statistical associations were investigated using serial linear models adjusted for false discovery rate and multivariate statistics.

RESULTS

Both hepatic fat and fibrosis had a significant effect on CT liver attenuation values. Several oligosaccharides (maltotriose, maltose, ribose, trehalose) and alkaline phosphatase were significantly and linearly increased with hepatic lipid content (all q < .05). On partial least square-discriminant analysis, β-hydroxybutyric acid was the most important discriminatory variable between fatty liver severity grades on histology. No significant associations were found with insulin, lipoproteins, and succinic acid.

CLINICAL RELEVANCE

Bearded dragons with hepatic lipid accumulation experienced multiple metabolic pathway disruptions, some being compatible with mitochondrial dysfunction. No evidence of insulin resistance or dyslipidemia was found. Hepatic biopsy and histopathology remain recommended for reliably diagnosing and staging fatty liver disease in bearded dragons.

Lipoprotein characterization in Quaker parrots (Myiopsitta monachus) using gel-permeation high-performance liquid chromatography

BACKGROUND

Lipid accumulation disorders, such as atherosclerosis and hepatic lipidosis, are common in psittacine birds and associated with various dyslipidemias. Gel-permeation high-performance liquid chromatography (GP-HPLC) is a reference method for advanced lipoprotein profiling based on particle size separation, followed by an analysis of lipid contents.

OBJECTIVES

The objectives were to (a) characterize Quaker parrot lipoproteins using a commercial GP-HPLC method (Liposearch panel), and (b) obtain preliminary information on the reliability of the Friedewald formula for low-density lipoprotein-cholesterol (LDL-C) measurements.

METHODS

Plasma samples were collected from 12 fasted healthy Quaker parrots. Cholesterol concentrations, triglyceride concentrations, particle sizes, and particle numbers were determined by GP-HPLC for four classes and 20 sub-fractions of lipoproteins. The LDL-C concentrations obtained using the Friedewald formula and direct measurements were compared with Bland-Altman plots. Alternate formulas were determined using multiple linear regression.

RESULTS

High-density lipoprotein (HDL) was the predominant lipoprotein in Quaker parrots, and most particles were of medium-to-small sizes belonging to two sub-fractions (average size, 10.6 nm). LDL was the second most common lipoprotein and included large-to-small particles belonging to three sub-fractions (average size, 24.9 nm). Very-low-density lipoproteins (VLDL) and portomicrons were present in low concentrations. The Friedewald formula underestimated LDL-C concentrations with a significant bias of 0.44 mmol/L. An alternate formula was proposed: LDL-C = 0.75*Non-HDL-C.

CONCLUSIONS

GP-HPLC allowed unprecedented characterization of plasma lipoproteins in Quaker parrots. Characterizing psittacine lipoprotein is useful for validation and interpretation of routine clinical tests as well as for use in epidemiologic and experimental research on psittacine lipid accumulation disorders.

Laboratory blood analysis in Strigiformes-Part I: hematologic reference intervals and agreement between manual blood cell counting techniques

BACKGROUND

While hematologic reference intervals (RI) are available for multiple raptorial species of the order Accipitriformes and Falconiformes, there is a lack of valuable hematologic information in Strigiformes that can be used for diagnostic and health monitoring purposes.

OBJECTIVES

The objective was to report RI in Strigiformes for hematologic variables and to assess agreement between manual cell counting techniques.

METHODS

A multi-center prospective study was designed to assess hematologic RI and blood cell morphology in owl species. Samples were collected from individuals representing 13 Strigiformes species, including Great Horned Owl, Snowy Owl, Eurasian Eagle Owl, Barred Owl, Great Gray Owl, Ural Owl, Northern Saw-Whet Owls, Northern Hawk Owl, Spectacled Owl, Barn Owl, Eastern Screech Owl, Long-Eared Owl, and Short-Eared Owl. Red blood cell count was determined manually using a hemocytometer. White blood cell count was determined using 3 manual counting techniques: (1) phloxine B technique, (2) Natt and Herrick technique, and (3) estimation from the smear. Differential counts and blood cell morphology were determined on smears. Reference intervals were determined and agreement between methods was calculated.

RESULTS

Important species-specific differences were observed in blood cell counts and granulocyte morphology. Differences in WBC count between species did not appear to be predictable based on phylogenetic relationships. Overall, most boreal owl species exhibited a lower WBC count than other species. Important disagreements were found between different manual WBC counting techniques.

CONCLUSIONS

Disagreements observed between manual counting techniques suggest that technique-specific RI should be used in Strigiformes.

Laboratory blood analysis in Strigiformes-Part II: plasma biochemistry reference intervals and agreement between the Abaxis Vetscan V2 and the Roche Cobas c501

BACKGROUND

Limited plasma biochemical information is available in Strigiformes. Only one study investigated the agreement between a point-of-care with a reference laboratory analyzer for biochemistry variables in birds.

OBJECTIVES

The objective was to report reference intervals (RI) for plasma biochemistry variables in Strigiformes, and to assess agreement between the Abaxis Vetscan V2 and Roche Cobas c501.

METHODS

A prospective study was designed to assess plasma biochemistry RI for concentration of calcium, phosphorus, total protein, albumin, globulin, glucose, bilirubin, uric acid, bile acids, sodium, potassium, and chloride, and activities of AST, GGT, CK, amylase, lipase, LDH, and GLDH. In addition, the agreement between the Vetscan and the Cobas in owl species was assessed.

RESULTS

A total of 190 individuals were sampled belonging to 12 Strigiformes species including Barn Owls, Barred Owls, Great Horned Owls, Eurasian Eagle Owls, Spectacled Owls, Eastern Screech Owls, Long-Eared Owls, Short-Eared Owls, Great Gray Owls, Snowy Owls, Northern Saw-Whet Owls, and Northern Hawk-Owls. Order-, species-, and method-specific RI were determined on both analyzers. Although Vetscan data were not equivalent to the Cobas, 4 analytes (glucose, AST, CK, and total protein, with correction for bias) were within acceptable agreement, 3 analytes (uric acid, calcium, and phosphorus) were within close agreement, and the remaining analytes were in strong disagreement. Species-specific differences were observed notably for the concentration of glucose in Barn Owls and electrolytes in Northern Saw-Whet Owls.

CONCLUSIONS

Overall, this study suggests that the Vetscan has acceptable clinical performance in Strigiformes for some analytes and highlights discrepancies for several analytes.

Complete blood cell count in psittaciformes by using high-throughput image cytometry: a pilot study

The avian hemogram is usually performed in veterinary diagnostic laboratories by using manual cell counting techniques and differential counts determined by light microscopy. There is no standard automated technique for avian blood cell count and differentiation to date. These shortcomings in birds are primarily because erythrocytes and thrombocytes are nucleated, which precludes the use of automated analyzers programmed to perform mammal complete blood cell counts. In addition, there is no standard avian antibody panel, which would allow cell differentiation by immunophenotyping across all commonly seen bird species. We report an alternative hematologic approach for quantification and differentiation of avian blood cells by using high-throughput image cytometry on blood smears in psittacine bird species. A pilot study was designed with 70 blood smears of different psittacine bird species stained with a Wright-Giemsa stain. The slides were scanned at 0.23 microm/pixel. The open-source softwares CellProfiler and CellProfiler Analyst were used for analyzing and sorting each cell by image cytometry. A "pipeline" was constructed in the CellProfiler by using different modules to identify and export hundreds of measures per cell for shape, intensity, and texture. Rules for classifying the different blood cell phenotypes were then determined based on these measurements by iterative feedback and machine learning by using CellProfiler Analyst. Although this approach shows promises, avian Leukopet results could not be duplicated when using this technique as is. Further studies and more standardized prospective investigations may be needed to refine the "pipeline" strategy and the machine learning algorithm.

Preliminary evaluation of a quantitative polymerase chain reaction assay for diagnosis of feline immunodeficiency virus infection

Enzyme-linked immunosorbent assay (ELISA) has high sensitivity and specificity for detection of feline immunodeficiency virus (FIV) antibodies, but does not distinguish between infection and vaccination. Real-time quantitative PCR (qPCR) assays may distinguish infected from vaccinated cats. Performance of a commercial qPCR assay was assessed with blood samples from 29 FIV-infected non-vaccinated, 26 FIV-uninfected vaccinated and 35 FIV-uninfected non-vaccinated cats. FIV infection status of cats was assigned based on a combination of vaccination and medical history, prevention of contact with potentially infected cats and two FIV antibody ELISA results. Test sensitivity and specificity were determined against this gold standard. The qPCR test yielded positive results in samples from 23/29 FIV-infected non-vaccinated, 2/26 FIV-uninfected vaccinated and 0/35 FIV-uninfected non-vaccinated cats. It was concluded that the qPCR test was moderately sensitive and highly specific for the diagnosis of FIV infection, and that it may be suitable for ruling out FIV infection in cats with a positive antibody ELISA result and unknown vaccination history.

Successful treatment of a radioulnar synostosis in a Mississippi kite (Ictinia mississippiensis)

A Mississippi kite (Ictinia mississippiensis) was presented to the Wildlife Hospital of Louisiana, School of Veterinary Medicine, Louisiana State University, for an inability to fly and was subsequently diagnosed with a minimally displaced, closed, simple, short oblique, diaphyseal fracture of the distal third of the right ulna. A figure-8 bandage was initially applied to the wing to stabilize the fracture. Over a 5-week period, the kite developed progressive reduction in wing extension, and serial radiographs revealed a bridging callus at the ulnar fracture site, as well as development of a radioulnar synostosis. To restore wing function and extension, surgical excision of the bony union between the radius and the ulna was performed, after which a polypropylene mesh implant was interposed between the 2 bones. Within 2 weeks after the surgical procedure, the kite had recovered normal wing extension and was able to fly without noticeable impairment. The bird was released 2 weeks after surgery. This case illustrates a common complication of external coaptation used as sole means of managing fractures of the avian ulna, radius, or both, which results from lack of interosseous soft tissue in the antebrachial area. On the basis of the successful outcome in this case, surgical excision of the interdiaphyseal callus and interposition of a polypropylene mesh could be a viable option for management of posttraumatic radioulnar synostosis in birds of prey.

Laboratory Findings, Histopathology, and Immunophenotype of Lymphoma in Domestic Ferrets

Lymphoma is a common tumor in ferrets, but anatomic distribution, histomorphology, immunophenotype, laboratory abnormalities, and response to chemotherapy are incompletely defined. In this study, lymphoma was diagnosed by histopathology of tumor tissue in 29 ferrets ranging in age from 0.8 to 8.5 years, including 12 males and 17 females. Tumors involved the viscera of the abdominal cavity (n = 11), thoracic cavity (n = 1), or abdominal and thoracic cavities (n = 7); the skin (n = 2); or the viscera of both body cavities plus other sites (n = 8). Microscopically, all tumors had diffuse architecture. Assessment by histomorphology and immunophenotype classified tumors as peripheral T-cell lymphoma (n = 17), anaplastic large T-cell lymphoma (n = 5), anaplastic large B-cell lymphoma (n = 4), diffuse large B-cell lymphoma (n = 1), and Hodgkin-like lymphoma (n = 2). Cytologic evaluation of tumor tissue was diagnostic in 11 of 13 cases. Twenty-two of 27 ferrets had anemia, 2 had leukemia, and 5 were neutropenic. Common comorbid disorders were adrenal disease (n = 27) and insulinoma (n = 6). Tumors most frequently involved mesenteric lymph nodes, while enlargement of peripheral lymph nodes was uncommon (n = 3). Ferrets with Hodgkin-like lymphoma had massive enlargement of single lymph nodes. Mean survival of ferrets not immediately euthanized was 5.0 months (T-cell lymphoma) and 8.4 months (B-cell lymphoma). Ferrets treated with chemotherapy survived an average of 4.3 months (T-cell lymphoma, n = 9) or 8.8 months (B-cell lymphoma, n = 4). Results indicate that lymphomas in ferrets most commonly affect abdominal viscera, may be amenable to cytologic diagnosis, are frequently associated with anemia and, in some cases, may be chemosensitive, resulting in relatively long survival times.