Evaluation of Renal Biomarkers, Including Symmetric Dimethylarginine, following Gentamicin-Induced Proximal Tubular Injury in the Rat.

Symmetric dimethylarginine (SDMA) is an excretory renal function biomarker shown to correlate well with glomerular filtration rate in dogs, cats, humans, and rats. The objectives of this study were to determine utility of serum SDMA as a renal biomarker in a rat model of gentamicin-induced renal injury and to provide validation of a commercially available SDMA immunoassay for rat serum. Rats were randomly assigned to one of three dose levels of gentamicin (20, 50, or 100 mg/kg) or a vehicle control group and dosed once daily by subcutaneous injection for either four or ten days. Serum and urine renal biomarker evaluation, including serum SDMA, hematologic and serum biochemical analysis, urinalysis, and histologic examination of kidney, were performed. Before biologic validation, analytic validation of the SDMA immunoassay for rat serum was performed, including assessment of assay accuracy, precision, analytical sensitivity, linearity, analyte stability, and interference testing. Among markers of excretory renal function, SDMA and serum creatinine increased earliest and at the lowest gentamicin concentrations and were significantly increased in both the 50- and 100- mg/kg dose levels in the four- and ten-dose treatment groups compared with controls. Time- and dose-dependent increases were noted for all urinary biomarkers investigated in this study, with microalbumin being most responsive and osteopontin least responsive for detection of gentamicin-induced injury across dose levels and schedules investigated. The SDMA immunoassay met all set quality requirements assessed in analytical validation. This study is the first to investigate performance of serum SDMA compared with other excretory renal function markers in a rat gentamicin acute toxicity model. In this study, serum SDMA was an earlier biomarker for detection of gentamicin-induced toxicity than serum cystatin C, BUN, and creatinine clearance. The SDMA immunoassay provides a reliable commercially available assay for future renal investigations in rat models.

Cytologic, histologic, microbiologic, and electron microscopic characterization of a canine Prototheca wickerhamii infection.

An adult dog was presented for chronic cough and a recent development of ulcerated, erythematous nares with nasal discharge. Cytology of enlarged peripheral lymph nodes revealed many intracellular and extracellular organisms. These round or rarely oval organisms measured approximately 5-9 µm in diameter and frequently contained several globular structures, ranging from deeply basophilic to magenta. A thin, clear halo was present. Smaller 1-2 µm, magenta forms were also observed. Fungal culture yielded small, wet, raised, irregularly shaped, white to pale tan colonies. Microbiologic staining of cultured material revealed features suggestive of algae. Histopathology of the lymph nodes revealed marked granulomatous inflammation with intralesional algal organisms suggestive of Prototheca. Electron microscopic findings were also consistent with protothecosis. Polymerase chain reaction, followed by direct DNA sequencing, identified the organism as Prototheca wickerhamii. A brief literature review discussing protothecosis in veterinary medicine is included.

Frequency and classification of errors in laboratory medicine at a veterinary teaching hospital in the United States.

BACKGROUND: The accuracy of laboratory data is of utmost importance. Data regarding laboratory error in human laboratories are often extrapolated into veterinary settings. One study investigated the rate and type of errors in a European commercial veterinary laboratory, but that data might not directly apply to an educational setting. OBJECTIVES: This study determined the frequency and type of errors in laboratory medicine at a veterinary teaching hospital. METHODS: Errors associated with clinical pathology samples were recorded over two 60-day periods. The first period included a time when new students and house officers started at the veterinary school. The second time period was 6 months later. The errors were assigned to categories, and the frequency of each was calculated. Sample hemolysis, icterus, and lipemia were evaluated separately using an automated index, as these conditions could be pathologic or the result of error. Frequencies of error and hemolysis, icterus, and lipemia were assessed between the groups. RESULTS: Total error rates were 4.7% and 3.5% for the first and second periods, respectively. The frequency of each error subclassification was similar to those observed in the veterinary and human literature, with preanalytic error predominating. Statistically significant differences in the overall error rate and percentage of preanalytic errors that occurred outside of and within the laboratory were observed comparing differences between the two periods. CONCLUSIONS: The overall error rate in this veterinary teaching hospital was slightly higher than that previously reported in other settings, although a proportion of errors was as expected. Areas needing improvement were identified, and strategies to reduce error could be developed.

Evaluation of an emergency medicine-focused clinical pathology training course for non-clinical pathology house officers.

OBJECTIVE: Determine whether an emergency medicine-focused clinical pathology training course improved the proficiency of house officers. DESIGN: Prospective blinded study. SETTING: Veterinary academic center. STUDY SUBJECT: House officers enrolled in programs other than clinical pathology. INTERVENTIONS: A 4-hour curriculum was provided by a board-certified specialist in veterinary clinical pathology. MEASUREMENTS AND MAIN RESULTS: A focused clinical pathology lecture course derived from historical teaching materials was delivered. A pre- and post-course multiple choice question examination was taken by the enrolled house officers, as well as a survey regarding their confidence level pre- and post-course utilizing a novel 5-point scoring system, ranging from 1 (very low confidence) to 5 (very high). A total of 21 house officers completed the study, 5 of which attended didactic lectures, 13 utilized an online learning platform, and 3 used a combination of both. There was a significant improvement in all house officers' post-training course examination results compared to pre-course results (pre-course examination score: mean 49% ±12; post-course examination score: mean 72.5% ± 15.7; P < 0.0001). There was a significant difference in pre- and post-course examination scores for each of the 3 topic areas: hematology (pre-course: mean 47% ±16; post-course: mean 71% ± 15.8; P ≤ 0.0001); urinalysis (pre-course: mean 65.7% ± 12.5; post-course: mean 87.6% ± 22.1; P = 0.0004); and fluid analysis (pre-course: mean 37.1% ± 14.1; post-course: mean 60.5% ± 15; P ≤ 0.0001). There was also a significant increase in the house officers' confidence score in overall clinical pathology skills (pre-course: mean 2.2 ± 1.5; post-course: 3.6±1.4; P = 0.0005). CONCLUSION: This study identified that a 4-hour clinical pathology training course relevant to small animal emergency medicine improved the knowledge and confidence of nonclinical pathology house officers. A similar training course may prove helpful in the future to improve the proficiency of emergency veterinarians.

Rhabdomyolysis and Artifactual Increase in Plasma Bicarbonate Concentration in an Amazon Parrot (Amazona species).

A 7-year-old male Amazon parrot housed outdoors presented with acute collapse, marked lethargy, and open-mouth breathing. The patient had stiffness of the pectoral muscles, and petechiation and ecchymosis noted around the eyes and beneath the mandible. Laboratory data revealed markedly increased aspartate aminotransferase, creatine kinase, and lactate dehydrogenase activity consistent with rhabdomyolysis, as well as markedly increased plasma bicarbonate concentration. Marked clinical improvement and resolution of laboratory abnormalities occurred with fluid therapy, administration of a nonsteroidal anti-inflammatory medication, and husbandry modifications, including indoor housing and dietary alteration. A spurious increase in bicarbonate measurement as documented in equine and bovine cases of rhabdomyolysis also occurred in this avian patient and must be considered for accurate interpretation of acid-base status in exotic species presenting with consistent clinical signs.

Macrocytosis secondary to hydroxyurea therapy.

A 10-year-old, male neutered Shetland Sheepdog was presented to the University of Florida for evaluation of a well-granulated mast cell tumor. Hydroxyurea therapy was instituted and serial CBCs showed persistent mild anemia and macrocytosis without a corresponding increase in polychromasia. The dog's MCV increased progressively, reaching its highest value of 100.0 fL after 6 months of treatment, and a diagnosis of macrocytosis associated with hydroxyurea therapy was made. The dog's increase in MCV was prominent, and rapidly decreased after the drug was discontinued, consistent with previous observations in human and canine subjects treated with hydroxyurea. Hydroxyurea is a cytotoxic chemotherapeutic agent used in a variety of conditions in human and veterinary medicine, and megaloblastic changes associated with its use have been described in multiple species. This report shows that hydroxyurea treatment is a differential diagnosis for prominent macrocytosis in dogs in the absence of other signs of erythrocyte regeneration.

The effect of urea on refractometric total protein measurement in dogs and cats with azotemia.

BACKGROUND: While protein is the predominant solute measured in plasma or serum by a refractometer, nonprotein substances also contribute to the angle of refraction. There is debate in the current literature regarding which nonprotein substances cause factitiously high refractometric total protein measurements, as compared to the biuret assay. OBJECTIVES: The purpose of the study was to determine if the blood of azotemic animals, specifically with increased blood urea concentration, will have significantly higher refractometric total protein concentrations compared to the total protein concentrations measured by biuret assay. METHODS: A prospective case series was conducted by collecting data from azotemic (n = 26) and nonazotemic (n = 34) dogs and cats. In addition, an in vitro study was performed where urea was added to an enhanced electrolyte solution at increasing concentrations, and total protein was assessed by both the refractometer and spectrophotometer. Statistical analysis was performed to determine the effect of urea. RESULTS: The refractometric total protein measurement showed a positive bias when compared to the biuret protein measurement in both groups, but the bias was higher in the azotemic group vs the nonazotemic group. The mean difference in total protein measurements of the nonazotemic group (0.59 g/dL) was significantly less (P < .01) than the mean difference of the azotemic group (0.95 g/dL). The in vitro experiment revealed a positive bias with a proportional error. CONCLUSIONS: This study demonstrated that increasing concentrations of urea significantly increased the total protein concentration measured by the refractometer as compared to the biuret assay, both in vivo and in vitro.

Antemortem Diagnosis of Coxiellosis in a Blue and Gold Macaw ( Ara ararauna).

A 15-year-old female blue and gold macaw ( Ara ararauna) was presented for evaluation after being found laterally recumbent, reluctant to move, and lethargic. Results of a complete blood count showed an increased number of immature heterophils with increased cytoplasmic basophilia and degranulation and the presence of a left shift. Radiographs and a computed tomography scan were performed and revealed a markedly enlarged spleen. An ultrasound-guided fine-needle aspirate of the spleen was submitted for cytologic examination and aerobic bacterial culture. While the culture revealed no growth, cytologic examination identified mononuclear phagocytes with cytoplasmic vacuoles containing structures consistent with bacteria. Pan-bacterial 16S rRNA polymerase chain reaction of the splenic sample followed by direct sequencing identified a Coxiella-like agent identical to one previously isolated in the liver of a golden-mantled rosella ( Platycercus eximius). Phylogenetic analysis shows that avian coxiellosis agents and Coxiella burnetii, the agent of Q fever, represent 2 independent events of development of vertebrate pathogenicity in this group of tick endosymbionts. This report suggests diagnostic and treatment directions for coxiellosis in avian patients and indicates where further study is needed.

Fungal myocarditis and pericardial effusion secondary to Inonotus tropicalis (phylum Basidiomycota) in a dog.

Fungal disease is a rare cause of pericardial effusion in dogs. This report describes the first case of fungal pericardial effusion and myocarditis secondary to the fungal organism Inonotus tropicalis. A 9-year-old female spayed French bulldog with a multi-year history of treatment with glucocorticoids for management of atopy was presented for exercise intolerance, ascites and weight loss. Physical examination and thoracic imaging revealed enlarged peripheral and cranial mediastinal lymph nodes, left ventricular thickening and cardiac tamponade secondary to pericardial effusion. Fine needle aspiration of the cranial mediastinal lymph node showed pyogranulomatous inflammation with short, thin and poorly septated hyphae. Culture of the aspirate yielded a fungal isolate identified as Inonotus tropicalis based on morphologic features and rRNA gene sequencing. Postmortem examination showed myocardial thickening with multifocal to coalescing, firm, white, ill-defined nodules. Histology confirmed the presence of disseminated fungal infection with extensive myocardial involvement. Inonotus tropicalis is an opportunistic poroid wood-decaying basidiomycete. Infection in this dog was likely the result of chronic immunosuppressive therapy.

Investigating the role of nucleotide-binding oligomerization domain-like receptors in bacterial lung infection.

Lower respiratory tract infections (LRTIs) are a persistent and pervasive public health problem worldwide. Pneumonia and other LRTIs will be among the leading causes of death in adults, and pneumonia is the single largest cause of death in children. LRTIs are also an important cause of acute lung injury and acute exacerbations of chronic obstructive pulmonary disease. Because innate immunity is the first line of defense against pathogens, understanding the role of innate immunity in the pulmonary system is of paramount importance. Pattern recognition molecules (PRMs) that recognize microbial-associated molecular patterns are an integral component of the innate immune system and are located in both cell membranes and cytosol. Toll-like receptors and nucleotide-binding oligomerization domain-like receptors (NLRs) are the major sensors at the forefront of pathogen recognition. Although Toll-like receptors have been extensively studied in host immunity, NLRs have diverse and important roles in immune and inflammatory responses, ranging from antimicrobial properties to adaptive immune responses. The lung contains NLR-expressing immune cells such as leukocytes and nonimmune cells such as epithelial cells that are in constant and close contact with invading microbes. This pulmonary perspective addresses our current understanding of the structure and function of NLR family members, highlighting advances and gaps in knowledge, with a specific focus on immune responses in the respiratory tract during bacterial infection. Further advances in exploring cellular and molecular responses to bacterial pathogens are critical to develop improved strategies to treat and prevent devastating infectious diseases of the lung.

Disseminated histoplasmosis (Histoplasma capsulatum) in a pet rabbit: case report and review of the literature.

A 2.5-year-old intact male miniature lop rabbit (Oryctolagus cuniculus) was presented with multiple nodules surrounding the eyes, nose, mouth, and prepuce. Cytological evaluation of the periocular nodules revealed the presence of intracellular (within macrophages) and extracellular yeast organisms. The yeast organisms were approximately 3-5 µm in diameter, round to oval, with a thin clear capsule, and contained an eccentrically placed basophilic crescent-shaped nucleus. The clinical pathological interpretation was granulomatous inflammation with intralesional yeast of a morphology consistent with Histoplasma spp. The rabbit was treated with microsized griseofulvin (25 mg/kg, orally, once a day) for 12 days pending final cytological diagnosis of histoplasmosis. No significant improvement was noted during the treatment period, and humane euthanasia was performed. Postmortem examination revealed the presence of intracellular and extracellular yeast organisms in the small intestine, skin (antebrachium, perioral, palpebral, perianal, and pinnal), penis, penile urethra, rectum, axillary lymph node, and conjunctiva. Postmortem fungal culture yielded Histoplasma capsulatum. Based on clinical and postmortem findings, a definitive diagnosis of disseminated histoplasmosis was made. Disseminated histoplasmosis appears to be unreported in rabbits. Although the treatment used did not provide noticeable improvement, available information on histoplasmosis treatment in other species has been reviewed to provide useful information for future management of this condition in rabbits.

Pulmonary histiocytic sarcoma in a rabbit.

An approximately 8-year-old male castrated Dutch rabbit was evaluated for a 6-day history of respiratory signs, which began as sneezing and progressed to tachypnea with anorexia. On physical examination, tachypnea and pale mucous membranes were noted. Thoracic radiographs revealed a soft tissue pulmonary mass, fine-needle aspirates of which confirmed a neoplasia with malignant features suspicious for a histiocytic sarcoma. The rabbit was discharged and due to a rapidly deteriorating condition, the owner declined chemotherapy with Lomustine and elected euthanasia of the rabbit. The affected lung was submitted for histopathology. Histologic sections of the lung were characterized by clusters of histiocytic cells and multinucleated giant cells with occasional invasion of blood and lymphatic vessels. The histologic diagnosis was histiocytic sarcoma. To the authors' knowledge, this is the first case report of histiocytic sarcoma in a rabbit. Based on the clinical and radiologic findings in this case, histiocytic sarcoma should be included in the list of differentials for rabbits presenting with respiratory signs and evidence of a pulmonary mass.