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Objectives: The aim of this study was to evaluate the results of serum allergen-specific IgE testing in cats with a clinical diagnosis of asthma and to determine if the number of allergens with positive IgE reactivity and magnitude of positive IgE responses would be associated with the severity of clinical signs or airway eosinophilia., Methods: Medical records from 2008 to 2018 were retrospectively reviewed. Inclusion required a diagnosis of feline asthma based on consistent clinicopathologic features and bronchoalveolar lavage (BAL) cytology with >10% eosinophils; additionally, cats needed to have the results of serum allergen-specific IgE tests., Results: Eighteen cases satisfied the inclusion criteria. Median age was 5 years and the most common presenting clinical sign was cough (n = 10/18). Most cats lived exclusively indoors (n = 13/18). The median percentage of BAL eosinophils was 47%. Serum allergen-specific IgE testing supported an underlying allergic etiology in 14/18 (78%) cats, with all but one having polysensitization. The severity of clinical signs and magnitude of airway eosinophilia did not correlate with the degree of positive IgE reactivity., Conclusions and Relevance: This study identified a strong association between the identification of allergen-specific IgE and cats with asthma, and the majority of these cats were polysensitized. However, larger numbers of allergens with positive IgE reactivity or magnitude of IgE reactivity were not significantly associated with clinical severity or airway eosinophilia. Knowledge of positive allergen-specific IgE results could guide allergen avoidance, regardless of the magnitude of IgE reactivity.

Allergic asthma is increasing in industrialized countries, especially in children. Rodent and human studies suggest an opportunity to "prevent" asthma in the perinatal period. The aims of this study were to create a more "natural" model of feline asthma by exposing offspring of asthmatic queens to Bermuda grass allergen (BGA) by inhalation only, and to investigate maternal-fetal-infant interactions in the development of asthma. Kittens from asthmatic queens were divided into four groups: maternal exposure to aerosolized BGA during the third trimester, neonatal exposure to aerosolized BGA in the first three months of life, both maternal and neonatal exposure, or saline control. Kittens failing to achieve an asthmatic phenotype based on bronchoalveolar lavage fluid (BALF) analysis by 6 months underwent traditional sensitization: adjuvanted allergen injection, intranasal allergen, and aerosol challenges. BALF was collected at 3, 4 and 6 months, and after sensitization at 8 months, and analyzed for eosinophil counts and BGA-specific IgG and IgA. Intradermal testing (IDT) was performed at 6 and 7 months. At six months none of the kittens had airway eosinophilia, BGA-specific IgG or IgA, and were non-responsive to IDT. After sensitization, kittens receiving neonatal aerosolization failed to develop airway eosinophilia as seen in the controls. Kittens exposed to BGA aerosols, either in-utero or neonatally, continued to lack IDT response. Chronic exposure to BGA aerosols failed to induce asthma in kittens, and instead tolerized the kittens to BGA. This is the first evidence that neonatal intervention could potentially "prevent" allergic asthma in cats., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Glucocorticoids (GCs) are palliative for allergic asthma, but allergen-specific immunotherapy (ASIT), which relies on identification of allergens, represents a potentially curative treatment. The purpose of this study was to determine if oral or inhaled GCs would interfere with identification of sensitizing allergens. The hypothesis was that oral but not inhaled GCs would interfere with accurate allergen-specific IgE identification determined by skin and serum testing in experimentally asthmatic cats. Asthma was induced in 18 cats using Bermuda grass allergen (BGA). Cats (n=6/group) were randomized to receive oral GCs (10mg prednisolone q 24 h), inhaled GCs (600 μg budesonide q 24 h) or placebo (q 24 h PO) for one month. Intradermal skin testing (IDST) and serum BGA-specific IgE were measured prior to, during and after treatment. A paired t test was used to compare groups pre- and post-treatment (P<0.05 significant). IDST reactivity was eliminated in 4/6, 3/6, and 1/6 cats receiving oral GCs, inhaled GCs, and placebo respectively. Two weeks after stopping treatment, IDST was again positive in all cats. Serum IgE reactivity to BGA was not significantly diminished by any treatment. In conclusion, a two-week withdrawal from GCs is adequate for IDST, but may not be necessary for serum IgE testing., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Intradermal skin testing (IDST) and allergen-specific IgE determination are used to determine allergen sensitization. In cats, studies have found poor correlation between the two tests. However, these studies were mainly conducted in pet cats sensitized to unknown allergens with unknown dose and duration of exposure. We hypothesized that in an experimental model of allergic sensitization where these variables are controlled, IDST would demonstrate greater sensitivity and specificity than would serum allergen-specific IgE determination. A model of feline asthma employing Bermuda grass allergen (BGA) or house dust mite allergen (HDMA) was used to test the hypothesis. Thirteen cats were assigned to undergo sensitization to BGA, HDMA or saline (placebo). Bronchoalveolar lavage fluid confirmed development of an asthmatic phenotype. Serum collection and IDST were performed on D0, D28 and D50. A portion of serum was pooled, and an aliquot heat inactivated (HI) to destroy IgE. Individual, pooled, and pooled HI samples were used for allergen-specific IgE determination using an Fc epsilon R1 alpha-based ELISA; pooled samples were also analyzed using an enzymoimmunometric assay. Sensitivity (SE), specificity (SP), and positive and negative predictive values (PPV and NPV) were calculated for IDST and for BGA- and HDMA-specific IgE. Combined results for IDST found SE=90.9%, SP=86.7%, PPV=83.3%, and NPV=92.9%. For ELISA-based serum IgE testing, the SE=22.7%, SP=100%, PPV=100% and NPV=63.8%. The enzymoimmunometric assay did not detect sensitizing IgE, but did detect IgE reactivity to a variety of irrelevant allergens (even in HI samples). Sensitivity of IDST was greater than sensitivity of serum IgE measurement supporting use as a screening test for aeroallergens. Both IDST and allergen-specific IgE determination via ELISA were specific; either test can be used to guide selection of allergens for immunotherapy. The enzymoimmunometric assay was unreliable and cannot be recommended.

Cats spontaneously develop eosinophilic airway inflammation and airway hyperreactivity that is very similar to human allergic asthma. In addition, household cats share environmental exposures to aeroallergens with humans. We review the scientific literature concerning the pathophysiology of feline asthma, including similarities to human asthma and evidence regarding environmental aeroallergen triggers. Results of pathophysiological studies suggest important similarities between human and feline responses to inhaled allergens. Only a few studies were found that examined the development of disease in cats to environmental aeroallergens. Limited evidence suggests that some environmental allergens can cause disease in both cats and humans. It appears that there is a need for greater communication between human and animal health professionals regarding environmental causes of asthma. Specifically, additional research into linkages between human and feline asthma using both molecular techniques and clinical epidemiological approaches could lead to improved understanding of the environmental risks. Finally, there should be consideration of use of naturally affected and/or experimentally induced (using clinically relevant allergens) asthmatic cats in preclinical trials for novel therapeutic interventions.

Rush immunotherapy (RIT) is effective for the treatment of experimental feline allergic asthma. In humans, the safety profile of immunotherapy is improved by delivering allergen by a mucosal route. We hypothesized that mucosal (intranasal) RIT would have similar efficacy to subcutaneous RIT with improved safety. Twelve cats sensitized and challenged with Bermuda grass allergen (BGA) were randomized to receive subcutaneous (SC) or intranasal (IN) RIT. Increasing doses of BGA (20-200 microg) were administered over 24h followed by 200 microg BGA weekly as maintenance. Adverse reactions were recorded. Clinical respiratory scores after BGA aerosol challenge, bronchoalveolar lavage fluid (BALF) % eosinophils, and cytokine concentrations were measured before RIT (day 1) and at months 1, 3 and 6 (M1, M3, M6). More adverse events were recorded with SC RIT (n=12) compared with IN RIT (n=6). Respiratory scores were lower by M6 compared with D1 in both the groups. The % BALF eosinophils declined significantly after RIT for both groups (mean+/-SEM, SC RIT D1 62+/-12, M6 9+/-4; IN RIT D1 54+/-9, M6 14+/-6). The BALF IL-4:IFN-gamma ratio significantly decreased over time in the IN RIT group (mean+/-SEM, D1 2.4+/-0.2, M6 1.0+/-0.2). While both protocols decreased eosinophilic airway inflammation, the SC RIT protocol did not cause life-threatening adverse events and demonstrated more consistent resolution of clinical signs after allergen challenge. Either protocol could be considered for the treatment of feline allergic asthma.