There are many causes of respiratory distress in cats, including pleural space disease, congestive heart failure, inflammatory bronchial disease, upper airway obstructions, tracheal rupture, pulmonary contusions, noncardiogenic pulmonary edema, smoke inhalation, thromboembolism, and pulmonary lesions or neoplasia. Many of these conditions can be diagnosed during an initial examination and thoracic imaging and by response to empirical treatment. However, there is a subset of cats with nonspecific mixed or pulmonary infiltrates in which the history and lack of response to empirical therapy do not aid in the diagnosis. Fifteen of these cats were identified and retrospectively reviewed; a major inclusion criterion was a diagnosis via necropsy. Pulmonary histopathologic evaluation revealed that these cats fell into 2 major groups: inflammatory disease (n = 8) and neoplasia (n = 7). There was no difference with respect to age, body weight, clinical signs, duration of hospitalization, examination findings, thoracic radiography, duration of hospitalization, treatment, or outcome. Cats with neoplasia had a significantly higher total white blood cell count than did cats with inflammatory lung disease. The total duration of illness ranged from 1 to 365 days (median, 30 days). Cats with viral or bacterial lung disease had the shortest duration of illness (1 to 7 days; median, 5 days). Premortem diagnosis was difficult, and fine-needle aspiration of the lung was the most useful diagnostic aid.

COMMENTARY: This article highlights the diagnostic challenges that can be presented by a cat with severe primary pulmonary parenchymal disease. It discusses some of the diagnostics available to mainstream veterinary patients and their sensitivity with respect to necropsy findings (actual diagnosis), but points out that often such cats are in a very fragile state and that it may be difficult to get an accurate diagnosis without advanced techniques. Unfortunately, clinical experience seems to be the best determinant of when to take the patient out of the oxygen cage and start diagnostics and other supportive care. Fortunately, more critical care facilities are available these days to provide ventilatory support that will buy these patients more time in which to be diagnosed and treated.

Clinical course, diagnostic findings and necropsy diagnosis in dyspneic cats with primary pulmonary parenchymal disease: 15 cats (1996-2002). Sauve V, Drobatz KJ, Shokek AB, et al. J VET EMER CRIT CARE 15:38-47, 2005.