Identification and Characterization of an Idiopathic Pulmonary Fibrosis‐Like Condition in Cats

Abstract

Interstitial lung diseases are a heterogeneous group of disorders with a variety of causes. In veterinary medicine, such lung diseases with a prominent fibrotic component of unknown etiology are often called idiopathic pulmonary fibrosis (IPF). In human medicine, this term is reserved for a distinct disease entity with specific histologic findings labeled as usual interstitial pneumonia (UIP). We identified 23 cats displaying histologic criteria of UIP The purpose of this retrospective study is to describe the presentation and response to therapy of these cats to better define this disease entity. All but 2 cats were middle aged to older (median 8.7 years), with no apparent sex or breed predisposition. Complaints included respiratory distress (n = 18) and cough (13). Duration of signs was less than 6 months in 17 cats. Physical-examination abnormalities included tachypnea, inspiratory or mixed inspiratory and expiratory effort, and adventitial lung sounds. No consistent hematologic or biochemical abnormalities, parasites, or positive serologic results for feline retroviruses, heartworms, or toxoplasmosis were present. Radiographic changes included dense patchy or diffuse interstitial, bronchiolar, and alveolar infiltrates. Analysis of bronchial lavage fluid revealed mild neutrophilic inflammation (n = 6) with no consistent pathogen growth. Clinical condition of 5 cats worsened after lavage. Coincident pulmonary neoplasia was identified in 6 cats. Response to therapy (corticosteroids, antibiotics, bronchodilators, and diuretics) was poor, and most cats died within days to months. Cats with histologic changes compatible with UIP had signs that mimicked many of the clinical findings of human IPF, and treatment response was similarly unrewarding.

An Official American Thoracic Society Workshop Report: Comparative Pathobiology of Fibrosing Lung Disorders in Humans and Domestic Animals

“…Although such diseases have been recognized for 20 years in horses, they have only more recently been described in dogs and cats (6,7,(9)(10)(11)(12). Although such diseases have been recognized for 20 years in horses, they have only more recently been described in dogs and cats (6,7,(9)(10)(11)(12).…”

Associations between respiratory signs and abnormalities reported in thoracic CT scans of cats

“…Computed tomography (CT) is increasingly used to investigate cats with thoracic conditions (Henninger , Cohn et al . , Oliveira et al . , Aarsvold et al .…”

Lower respiratory tract endoscopy in the cat

“…While an endoscopic biopsy or brushing can detect neoplasia that is endobronchial, these lesions are rare and typically require a lung biopsy to obtain a histologic diagnosis. 7,8 Another advantage of performing bronchoscopy rather than blind BAL is the unique ability to undertake therapeutic interventions. For example, bronchoscopy can be used to visualize and remove foreign material.…”