Radiographic Appearance of Presumed Noncardiogenic Pulmonary Edema and Correlation With the Underlying Cause in Dogs and Cats

Abstract

Noncardiogenic pulmonary edema is an important cause of respiratory disease in dogs and cats but few reports describe its radiographic appearance. The purpose of this retrospective case series study was to describe radiographic findings in a large cohort of dogs and cats with presumed noncardiogenic pulmonary edema and to test associations among radiographic findings versus cause of edema. Medical records were retrieved for dogs and cats with presumed noncardiogenic edema based on history, radiographic findings, and outcome. Radiographs were reviewed to assess lung pattern and distribution of the edema. Correlation with the cause of noncardiogenic pulmonary edema was evaluated with a Fisher's exact test. A total of 49 dogs and 11 cats were included. Causes for the noncardiogenic edema were airway obstruction (n = 23), direct pulmonary injury (n = 13), severe neurologic stimulation (n = 12), systemic disease (n = 6), near-drowning (n = 3), anaphylaxis (n = 2) and blood transfusion (n = 1). Mixed, symmetric, peripheral, multifocal, bilateral, and dorsal lung patterns were observed in 44 (73.3%), 46 (76.7%), 55 (91.7%), 46 (76.7%), 46 (76.7%), and 34 (57.6%) of 60 animals, respectively. When the distribution was unilateral, pulmonary infiltration involved mainly the right lung lobes (12 of 14, 85.7%). Increased pulmonary opacity was more often asymmetric, unilateral, and dorsal for postobstructive pulmonary edema compared to other types of noncardiogenic pulmonary edema, but no other significant correlations could be identified. In conclusion, noncardiogenic pulmonary edema may present with a quite variable radiographic appearance in dogs and cats.

Postobstructive negative pressure pulmonary oedema in a dog

“…In dorsal recumbency, the caudal lung lobes seem to be more affected 26. A recent case series focused on the radiographic appearance of non‐cardiogenic pulmonary oedema suggested that a dorsal distribution of the lung lesions seemed to be more often observed in NPPO than in other causes of non‐cardiogenic pulmonary oedema, although, the authors could not give an explanation to this finding 5…”

“…Postobstructive pulmonary oedema type 1 is also known as negative pressure pulmonary oedema (NPPO) and has been highlighted as a potential complication in the postanaesthetic period in people and horses 3 4. Multiple causes have been attributed to the development of NPPO: brachycephalic obstructive airway syndrome (BOAS), strangulation, choking, near drowning, airway collapse, laryngeal mass, laryngeal paralysis, endotracheal tube (ETT) obstruction, laryngospasm and partial occlusion of the upper airway tract with a foreign body or other mass 2 5…”

“…In 1989 and 1995, two case series described the development of pulmonary oedema in conscious dogs due to UAO resulting from laryngeal paralysis, laryngeal oedema or obstructive airway masses 8 9. Another case series was recently published describing the radiographic appearance of 23 cases with presumed postobstructive pulmonary oedema in conscious dogs 5…”

Clinical features of canine pulmonary veno‐occlusive disease and pulmonary capillary hemangiomatosis

“…Thoracic radiographic evaluation was based on previously described methods . When radiographs from multiple time points were available for a patient, the last set of radiographs were used for scoring evaluation.…”

“…Cranial lung lobe pulmonary vessels were considered normal if diameters were less than the width of the proximal one‐third of the 4th rib . Caudal pulmonary vessels were normal if diameters were less than the width of the 9th rib where they crossed . Blood vessels were considered tortuous if any deviation from their expected course was identified.…”