Prevalence of B-Lines in cats with asthma

Abstract: Background – Asthma is common in cats and people, with 30% of asthmatic children having B-lines identified on lung ultrasound (LUS), that correlate with the severity of asthma. Although LUS is often used to document the sonographic presence of hyperechoic vertical artifact, particularly B-lines, research is lacking on its application in feline asthma. Hypothesis/Objectives – The objective is to prospectively evaluate if asthmatic cats have B-lines, and if they correlate to disease severity as assessed by oxygen and hospital admission. Animals – Cats were identified with asthma based on combination of history, clinical signs, radiographs and airway cytology. Methods – The presence/absence of sonographic B-lines, and when present, their quantification was recorded. Cats were classified as outpatient/inpatient, and for cats receiving oxygen, duration of therapy was recorded. Descriptive statistics were calculated, and a T-test was used to compare B-lines with duration of stay and supplemental oxygen requirements (significance considered p ≤ 0.05). Results – 10 cats were included. B-lines were identified in 4 cats (range 2-5/cat) and absent in 6. Nine cats received oxygen. Seven cats were hospitalized. There was no difference between length of stay or duration of oxygen supplementation in cats with or without B-lines. Conclusions and Clinical Importance – The presence of B-lines does not exclude a diagnosis of asthma, although B-lines were uncommon. Evaluation of a larger number of cats is required for more definitive statements on the predictive value of B-lines regarding severity of feline asthma.