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IDENTIFICATION AND CHARACTERIZATION OF AN IDIOPATHIC PULMONARY FIBROSIS-LIKE CONDITION IN CATS
Cohn, L. A., C. R. Norris, E. C. Hawkins, J A. Dye, Johnson, Cheri A, AND K. J. Williams. IDENTIFICATION AND CHARACTERIZATION OF AN IDIOPATHIC PULMONARY FIBROSIS-LIKE CONDITION IN CATS. JOURNAL OF VETERINARY INTERNAL MEDICINE 18(5):632-641, (2004).
The purpose of this retrospective study is to describe the presentation and response to therapy of cats with interstitial lung disease to better define their disease entity and to relate it to clinical findings in humans.
Interstitial lung diseases are a heterogeneous group of disorders due to a variety of causes. In veterinary medicine, those 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 histological 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 their disease entity.
Most cats were middle aged to older (median 8.7 years), with no apparent gender or breed predisposition. Historical complaints included respiratory distress (n=18) and cough (13); in most cases duration of signs was less than 6 months. Physical examination abnormalities included tachypnea, inspiratory or mixed inspiratory/expiratory effort, and adventitial sounds. No consistent hematologic or biochemical abnormalities, parasites, or positive serologic results for feline retroviruses, heartworms, or toxoplasmosis were found. Radiographic changes included dense patchy or diffuse interstitial, bronchiolar, and alveolar infiltrates. Lavage fluid analysis most commonly revealed mild neutrophilic inflammation (n=6) with no consistent pathogen growth; several cats worsened after lavage. In addition to having the inclusion criteria of UIP, coincident pulmonary neoplasia was identified in 6 cats. Response to therapy (including steroids, antibiotics, bronchodilators, and diuretics) was poor, and most cats succumbed within weeks 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.