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Background: Crossmatching is used to prevent life-threatening transfusion reactions in horses. Laboratory methods are laborious and technically challenging, which is impractical during emergencies., Hypothesis/objectives: Evaluate agreement between a stall-side crossmatch kit (KIT) and a laboratory method (LAB) in horses with known and unknown blood types., Animals: Twenty-four blood-typed and alloantibody-screened healthy adult horses (Aim 1) and 156 adult horses of unknown blood type (Aim 2)., Methods: Prospective, blinded study. Expected positive (n = 35) and negative (n = 36) crossmatches among 24 antibody and blood-typed horses were used to determine sensitivity and specificity of KIT and LAB against the reference method. Agreement in 156 untyped horses was evaluated by reciprocal crossmatch (n = 156)., Results: Sensitivity (95% confidence interval [CI]) for LAB and KIT compared with expected reactions was 77.1% (59.9%-90.0%) and 91.4% (77.0%-98.2%), and specificity 77.8% (60.9%-89.9%) and 73.5% (55.6%-87.1%), respectively. The KIT was 100% sensitive for Aa reactions; LAB was 100% sensitive for Qab; and both were 100% sensitive for Ca. Cohen's κ agreement for LAB and KIT with expected positive and negative reactions (n = 71) was moderate (0.55 [0.36-0.74]) and substantial (0.65 [0.47-0.82]), respectively. Agreement was fair comparing LAB with KIT in Aim 1 (0.30 [0.08-0.52]) and in untyped horses in Aim 2 (0.26 [0.11-0.41])., Conclusions and Clinical Importance: Agreement between KIT and LAB with expected reactions was blood type dependent. Performance of both methods depends on blood type prevalence., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background: Culicoides hypersensitivity (CH), an intensely pruritic and seasonal allergic dermatitis, is a common allergic disease affecting horses worldwide. Currently, there is no validated clinical scoring system for the quantification of clinical signs associated with CH. Objectives: To (i) determine the best cut‐off point of three scoring systems, (ii) test the accuracy of each system when compared to the clinical diagnosis of an experienced veterinarian and (iii) assess agreement between systems. Animals: Icelandic horses (n = 20); eight with CH and 12 unaffected, from a research herd receiving no treatments for allergic dermatitis. Methods and materials: Lesion scores were recorded biweekly from April until September with three clinical scoring systems (A, B and C) by a single observer initially blinded to CH status. Separate logistic regression analyses for each time point were used to determine appropriate cut‐offs for CH classification. Spearman's rho and Cohen's kappa were calculated to analyze correlation of scores and agreement of CH categorization between systems, respectively. Results: The best allergic cut‐off scores for system A, B and C were determined to be three, eight and 12, respectively. For each system median areas under the curve (>0.85) were excellent and discriminatory ability for correctly classifying CH status was strong. Excellent correlation between scores for each system (Spearman's rho > 0.96) and excellent intersystem agreement for CH categorization (kappa ≥ 0.73) were found across scoring time points. Conclusion and clinical importance: Results support the use of these scoring systems as templates for the future standardization of a CH clinical scoring system. [ABSTRACT FROM AUTHOR]