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Abstract Background In dogs with idiopathic epilepsy (IE), 33% develop resistance to conventional anti‐seizure medication (ASM) despite adequate treatment. In human medicine, an immune‐mediated etiology is suspected in a subset of ASM‐resistant patients with epilepsy and cerebrospinal fluid (CSF)‐specific immunoglobulin G (IgG)‐type oligoclonal bands (OCBs) have been detected. In dogs, cases of autoimmune encephalitis recently were reported. Neuroinflammation may provide an additional explanation for the lack of response of certain dogs with IE to ASM. Hypothesis Cerebrospinal fluid‐specific OCBs are found in a subgroup of dogs with ASM‐resistant IE. Animals Eighty‐four dogs with IE were recruited from 3 referral centers and classified based on their response to ASM treatment (responsive, n = 56; resistant, n = 28). Methods Detection of OCBs was performed using isoelectric focusing (IEF) followed by immunoblotting. Associations of CSF‐specific OCBs with seizure type, severity, and response to ASM were calculated using logistic regression models. Results The overall frequency of CSF‐specific OCBs in dogs with IE was 15.5% (95% confidence interval [CI], 8.5%‐25%). In dogs with ASM‐resistant IE, 21.4% (6/28) had CSF‐specific OCBs compared with only 12.5% (7/56) in those responsive to ASM, but no evidence of an association was detected (odds ratio, 1.9; 95% CI, 0.57‐6.35; P = .29). Conclusions and Clinical Importance Cerebrospinal fluid‐specific OCBs were detected in a subgroup of dogs with IE. This finding could indicate that intrathecal IgG synthesis as a sign of neuroinflammation may play a role in disease pathogenesis.

Abstract Background Severe asthma (SA) in horses, resembling human asthma, is a prevalent, debilitating allergic respiratory condition marked by elevated allergen‐specific immunoglobulin E (IgE) against environmental proteins; however, research exploring the exposome's influence on IgE profiles is currently limited but holds paramount significance for diagnostic and therapeutic developments. Animals Thirty‐five sports horses were analyzed, consisting of environmentally matched samples from France (5 SA; 6 control), the United States (6 SA; 6 control), and Canada (6 SEA; 6 control). Methods This intentional cross‐sectional study investigated the sensitization profiles of SA‐affected and healthy horses via serological antigen microarray profiling. Partial least square‐discriminant analysis (PLS‐DA) was used to identify and rank the importance of allergens for class separation (ie, affected/non‐affected) as variable influence of projection (VIP), and allergen with commonality internationally established via frequency analysis. Results PLS‐DA models showed high discriminatory power in predicting SA in horses from Canada (area under the curve [AUC] 0.995) and France (AUC 0.867) but poor discriminatory power in horses from the United States (AUC 0.38). Hev b 5.0101, Cyn D, Der p 2, and Rum cr were the only shared allergens across all geographical groups. Conclusions and Clinical Importance Microarray profiling can identify specific allergenic components associated with SA in horses, while mathematical modeling of this data can be used for disease classification, highlighting the variability of sensitization profiles between geographical locations and emphasizing the importance of local exposure to the prevalence of different allergens. Frequency scoring analysis can identify important variables that contribute to the classification of SA across different geographical regions.

Abstract Background The diagnostic value of allergen‐specific immunoglobulin E (IgE) in horses with asthma is uncertain. A recently developed protein microarray detected abnormally high latex‐specific IgE concentrations in the serum of horses with severe asthma. Objectives The main objective was to characterize the IgE profiles of asthmatic horses in Switzerland using a protein microarray platform in serum and bronchoalveolar lavage fluid (BALF). The secondary objective was to determine whether serological and BALF allergen‐specific IgE concentrations correlated. Animals Forty‐four asthmatic and 39 control horses ≥5 years of age. Methods This prospective cross‐sectional study investigated the sensitization profiles of horses with asthma compared with environmentally matched healthy controls. Both serum and BALF were analyzed using the protein microarray. Partial least square‐discriminant analysis (PLS‐DA) was used to identify and rank the importance of the allergens for class detection (ie, asthma vs control), with a variable influence on the projection (VIP) >1 considered significant. Results The allergens that best discriminated (VIP >1) asthmatic horses from controls were proteins derived from fungi (Aspergillus fumigatus), insects (Culicoides spp.), and latex (Hevea brasiliensis). The serological model predictive ability was markedly inferior (area under the curve [AUC] 0.585, 95% confidence interval [CI]: 0.454‐0.747) to that of the BALF (AUC 0.751, 95% CI: 0.582‐0.866). The two models shared nine allergens, of which eight showed significant weak to moderate correlations. Conclusion and Clinical Importance The concentrations of several allergen‐specific IgE were higher in asthmatic horses. The protein microarray performed better on BALF than serum for detection of asthma. Serological IgE concentrations do not closely correlate with BALF concentrations and should be interpreted with caution.

Abstract Background Endothelial dysfunction might contribute to the development of leptospiral pulmonary hemorrhage syndrome (LPHS). Hypothesis Serum concentrations of markers of endothelial activation and dysfunction are higher in dogs with leptospirosis and correlate with the occurrence of LPHS and a higher case fatality rate. Animals Clinically healthy dogs (n = 31; 10/31 dogs confirmed healthy based on no detected abnormalities on blood work), dogs with leptospirosis with LPHS (n = 17) and without LPHS (n = 15), dogs with acute kidney injury not due to leptospirosis (AKI‐nL, n = 34). Methods Observational study. Serum concentrations of soluble intercellular adhesion molecule 1 (sICAM‐1), vascular endothelial growth factor (VEGF), and angiopoietin‐2 (Ang‐2) at admission were compared between groups. Correlations with outcome and the accuracy to predict LPHS were examined. Results Soluble intercellular adhesion molecule (sICAM‐1), VEGF, and Ang‐2 concentrations were higher in dogs with AKI‐nL (sICAM‐1 34.7 ng/mL, interquartile range [IQR] = 24.4‐75.5; VEGF 43.1 pg/mL, IQR = 12.3‐79.2; Ang‐2 8.5 ng/mL, IQR = 6.2‐12.3), leptospirosis without LPHS (sICAM‐1 45.1 ng/mL, IQR = 30.6‐59.0; VEGF 32.4 pg/mL, IQR = 12.5‐62.6; Ang‐2 9.6 ng/mL, IQR = 6.9‐19.3), and LPHS (sICAM‐1 69.7 ng/mL, IQR = 42.1‐89.1; VEGF 51.8 pg/mL, IQR = 26.3‐96.7; Ang‐2 8.0 ng/mL, IQR = 5.6‐12.2) compared to controls (P

Abstract Background Severe asthma in horses, known as severe equine asthma (SEA), is a prevalent, performance‐limiting disease associated with increased allergen‐specific immunoglobulin E (IgE) against a range of environmental aeroallergens. Objective To develop a protein microarray platform to profile IgE against a range of proven and novel environmental proteins in SEA‐affected horses. Animals Six SEA‐affected and 6 clinically healthy Warmblood performance horses. Methods Developed a protein microarray (n = 384) using protein extracts and purified proteins from a large number of families including pollen, bacteria, fungi, and arthropods associated with the horses, environment. Conditions were optimized and assessed for printing, incubation, immunolabeling, biological fluid source, concentration techniques, reproducibility, and specificity. Results This method identified a number of novel allergens, while also identifying an association between SEA and pollen sensitization. Immunolabeling methods confirmed the accuracy of a commercially available mouse anti‐horse IgE 3H10 source (R2 = 0.91). Biological fluid source evaluation indicated that sera and bronchoalveolar lavage fluid (BALF) yielded the same specific IgE profile (average R2 = 0.75). Amicon centrifugal filters were found to be the most efficient technique for concentrating BALF for IgE analysis at 40‐fold. Overnight incubation maintained the same sensitization profile while increasing sensitivity. Reproducibility was demonstrated (R2 = 0.97), as was specificity using protein inhibition assays. Arthropods, fungi, and pollens showed the greatest discrimination for SEA. Conclusions and Clinical Importance We have established that protein microarrays can be used for large‐scale IgE mapping of allergens associated with the environment of horses. This technology provides a sound platform for specific diagnosis, management, and treatment of SEA.

Background Genetic, epidemiologic, and clinical evidence suggests that, in horses, there are manifestations of hypersensitivity that can occur together. Objectives To investigate whether concurrent insect bite hypersensitivity (IBH) and severe equine asthma (EA) is associated with higher allergen‐specific and total serum immunoglobulin E (IgE) concentrations than only EA or IBH. Animals Healthy control horses (C, n = 40), horses with IBH (IBH, n = 24), severe EA (EA, n = 18), and both conditions (IBH/EA, n = 23) were included. Methods In our retrospective comparative study, sera from horses with signs of severe EA, IBH, and control animals were used. IgE specific for 15 recombinant (r) allergens as well as total serum IgE concentrations were measured by enzyme‐linked immunosorbent assay. Results Group IBH (median sum r‐Culicoides IgE: optical density at 405 nm [OD405] = 3.54 [0.48‐15.07]) and group IBH/EA (OD405 = 4.55 [0.46‐17.15]) had significantly (P .05) differences between group IBH and group IBH/EA. No significant differences among the groups were found for the other r‐allergens or total serum IgE concentration. Compared to controls, horses with severe IBH had significantly increased IgE concentration to 5 Culicoides r‐allergens (P