Idiopathic Chronic Eosinophilic Pneumonia in 7 Horses

Abstract

Background: Idiopathic chronic eosinophilic pneumonia of horses is incompletely described. Objectives: To describe the physical examination, clinicopathologic, histopathologic, and radiographic features and response to corticosteroid treatment of idiopathic chronic eosinophilic pneumonia of horses.Animals: Seven horses with eosinophilic pneumonia. Methods: Retrospective, descriptive study.Results: Anamnesis, clinical signs, and clinicopathologic and radiologic findings in 7 adult horses with histologically confirmed eosinophilic pneumonia were reviewed. The horses were examined for signs of chronic respiratory disease. The horses ranged in age from 8 to 20 years. Significant findings on physical examination included tachypnea and abnormal respiratory sounds. Thoracic radiography revealed severe diffuse interstitial patterns of increased pulmonary density in all horses. There was a predominance of eosinophils in bronchoalveolar lavage fluid (BALF), and 6 of 7 horses had peripheral blood eosinophilia. Lung biopsies revealed eosinophilic infiltrates in all horses. Dexamethasone was administered to 3 horses and resulted in short-term clinical improvement in all three.Conclusions and Clinical Importance: A diagnosis of idiopathic eosinophilic pneumonia should be considered in horses with a history of chronic pulmonary disease, diffuse interstitial pattern of increased pulmonary density on thoracic radiographs, and a predominance of eosinophils in BALF. Horses with this condition may show a temporary response to treatment with dexamethasone.

Idiopathic Eosinophilic Pneumonia with Associated Pulmonary Vasculitis in Horse: A Case Series

“…In both studies, vasculitis was not reported. 6,7 In the present case series based on histologic findings and the absence of an etiologic agent, a diagnosis of idiopathic eosinophilic pneumonia with associated vasculitis was made. Interestingly vasculitis has not been described in lungs of horse with eosinophilic pneumonia before this study.…”

“…[3][4][5][6][7] Eosinophilic infiltrates of equine lungs are observed during parasitic infections or allergic condition 8,9 but eosinophilic pneumonia with vasculitis, which are not associated with parasitic infection and without the evidence of involvement of other organs have not been previously reported in horses. In the present study, we describe the gross and microscopic lesions of idiopathic eosinophilic pneumonia with associated vasculitis in 11 horses.…”

Inflammatory Airway Disease of Horses—Revised Consensus Statement

“…Eosinophilic inflammation in BALF is typically more severe and persistent in parasitic pneumonitis and idiopathic eosinophilic pneumonia than in eosinophilic IAD 100, 102. Furthermore, direct examination of tracheal wash fluid might reveal the presence of larvae.…”

Clinical Approach to Commonly Encountered Problems

“…[215][216][217][218] Included in this syndrome are inflammatory airway disease (IAD, mild to moderate equine asthma) and recurrent airway obstruction (RAO, severe equine asthma). [223][224][225][226] It is not uncommon for horses to cough occasionally, especially at the beginning of exercise. RAO primarily affects horses over 7 years of age.…”

“…Acute viral infection can be associated with leukopenia characterized primarily by lymphopenia. 216,[224][225][226] Hypercalcemia can be seen in some horses with malignancy. Neutrophilia and hyperfibrinogenemia are seen with many inflammatory conditions, especially bacterial or fungal pneumonia.…”