Nicole J. Fernandez

Evaluation of a risk‐screening questionnaire to detect equine lung inflammation: Results of a large field study

REASONS FOR PERFORMING STUDY The diagnosis of equine recurrent airway obstruction (RAO) and inflammatory airway disease (IAD) is based on clinical signs and increased inflammatory cell percentages in the bronchoalveolar lavage (BAL) fluid. Since a BAL is an invasive procedure, a risk-screening questionnaire (RSQ) would be a valuable screening tool for lung inflammation. OBJECTIVE To evaluate the accuracy of a RSQ to detect lower airway inflammation (LAI) in a large population of horses. METHODS A standardised BAL was performed in the field on 167 horses in Alberta, Canada. Horses were separated into 3 categories: 1) BAL normal; 2) BAL mild to moderate LAI (MLAI), and 3) BAL severe LAI (SLAI). The horse owners were asked to complete a RSQ. The RSQ scores were compared to the BAL results to determine the likelihood of a horse having MLAI, SLAI or no LAI. RESULTS Based on BAL cytology, 28 (17%) horses were normal and 139 (83%) were abnormal, with 110 (66%) showing MLAI and 29 (17%) SLAI. Horses with SLAI and MLAI had a mean RSQ score of 0.95 and 0.70, respectively, compared to 0.60 for normal BAL horses. Horses with SLAI showed more clinical signs than normal and MLAI horses. The sensitivity and negative predictive values of the RSQ for detecting SLAI using a cut-off score of 0.87, were excellent at 0.90 (95%CI 0.73-0.98) and 0.96 (95%CI 0.82-1.00). Questions on the clinical signs typically found in RAO cases differed significantly between horses with BAL SLAI and those with BAL normal. CONCLUSIONS Prevalence of MLAI was high in this population. Although the RSQ did not allow differentiating normal horses from horses with MLAI, it has a high sensitivity to detect horses with SLAI and is therefore a good screening tool for SLAI.

Reliability of 400-cell and 5-field leukocyte differential counts for equine bronchoalveolar lavage fluid

BACKGROUND Reliable enumeration of mast cells and eosinophils in equine bronchoalveolar lavage (BAL) fluid is important because small increases in the percentages of these cells support the clinical diagnosis of inflammatory airway disease (IAD). Increases in BAL neutrophils also occur with IAD but are not specific due to overlap between IAD and recurrent airway obstruction (RAO). OBJECTIVES The objectives of this study were to evaluate the reliability of a standard 400-cell leukocyte differential count and an alternate method evaluating 5 microscopic fields at 500× magnification in equine BAL fluid cytocentrifuged preparations. METHODS BAL samples from 60 horses with and without pulmonary inflammation were evaluated using 400-cell and 5-field leukocyte differential counting methods. Reliability of enumeration of each leukocyte type was assessed by calculating and comparing intraclass correlation coefficients (ICC). Reliability of mast cell enumeration was further evaluated by comparing ICCs of slides with different cell densities. RESULTS Reliability was higher for all cell types with the 5-field method; however, overall the difference between methods was not statistically significant. Neutrophil reliability was high (ICC > 0.90) with both methods. Adequate reliability (ICC > 0.85) for mast cells was achieved only with the 5-field method on slides with higher cell density. CONCLUSION Enumeration of mast cells is unreliable when the standard 400-cell differential counting method is used, whereas the 5-field method on slides with higher cell density reached acceptable reproducibility. Neutrophil percentages were highly reliable with both methods.

Bronchial collapse during bronchoalveolar lavage in horses is an indicator of lung inflammation

REASONS FOR PERFORMING STUDY The bronchoalveolar lavage (BAL) procedure can return variable volumes of fluid, possibly depending on the presence of bronchial collapse during fluid aspiration and on the severity of lung inflammation. OBJECTIVES We tested the hypothesis that horses with bronchial collapse during BAL are at higher risk of having severe lung inflammation. STUDY DESIGN Prospective field study. METHODS Bronchial collapse was graded using a new simple scoring method (0, 1 or 2) during a standardised BAL procedure in the field on 131 horses with normal, mild/moderate or severe lower airway inflammation on cytology of BAL fluid. RESULTS Of the 131 horses, 37 (28%), 55 (42%) and 39 (30%) horses had bronchial collapse scores of 0, 1 and 2, respectively. There was a difference in collapse scores between all the BAL inflammation categories (P<0.001). Severe collapse had a positive predictive value of 0.95 for both mild/moderate and severe BAL inflammation, with a prevalence of 63% and 20%, respectively. The BAL fluid return volume in the horses with severe collapse scores was lower than volumes in the partial (score 1/2) and no collapse (score 0/2) groups (P<0.001). The BAL fluid volume was negatively correlated with BAL neutrophil percentage (P<0.001). CONCLUSIONS Airway collapse during BAL is associated with airway inflammation and neutrophilia. POTENTIAL RELEVANCE During a standardised BAL procedure, clinicians can expect lung inflammation in horses that have bronchial collapse and bronchial collapse in horses with lung inflammation. Lung inflammation may be a contributing factor in the mechanism of bronchial collapse during BAL in horses.

What is your diagnosis? Ventral neck mass in a dog

: A 14-year-old male Labrador Retriever was presented for lethargy and collapse. On physical examination, numerous abnormalities were found, including a large ventral neck mass (100 cm(3)) in the area of the thyroid gland. Fine-needle aspirates revealed 2 apparent populations of cells: one suspected to be a well-differentiated thyroid carcinoma, and the other consisting of large pleomorphic to spindloid cells suggestive of sarcoma. Two days later, the dog died at home. A full necropsy was not performed, but examination of the head and neck revealed a well-encapsulated mass adjacent to the cranial trachea and larynx. A section of the mass was evaluated histologically and a diagnosis of anaplastic thyroid carcinoma was made. Immunohistochemical evaluation with antibodies to thyroglobulin, cytokeratin, and vimentin confirmed distinct populations of malignant epithelial and malignant mesenchymal cells, and the diagnosis was amended to thyroid carcinosarcoma. Thyroid carcinosarcoma is a rare neoplasm in dogs in which the cell type comprising the mesenchymal component can vary. Immunochemistry to demonstrate the 2 cell types may be necessary to differentiate thyroid carcinosarcoma from anaplastic thyroid carcinoma.