Comparison of Two Lung Ultrasound Protocols for Identification and Distribution of B‐, I‐, and Z‐Lines in Clinically Healthy Cats

ABSTRACT Objective To investigate the frequency and distribution of B‐, I‐, and Z‐lines in clinically healthy cats and to determine whether there is a difference in frequency and distribution between two different lung ultrasound protocols. Design Prospective cross‐sectional study from June to September 2022. Setting Companion animal referral hospital. Animals Sixty‐four cats determined to be healthy based on history and physical examination. Interventions All cats had point‐of‐care lung ultrasound performed with frequency of B‐, I‐, and Z‐lines recorded. Findings of a modified Calgary pleura and lung ultrasound (PLUS) protocol (19 sites recorded) and a veterinary Brief Lung Ultrasound Exam (VetBLUE) protocol (nine sites), both including the subxiphoid site, were compared. Measurements and Main Results B‐lines were identified in 14%–27% of cats depending on the protocol used, with a median of <3 B‐lines total per cat, <2 B‐lines per hemithorax, and ≤2 positive B‐line sites per hemithorax, regardless of the protocol used. The total number of B‐, I‐, or Z‐lines identified was significantly higher for the modified Calgary PLUS compared with VetBLUE. The number of cats with ≥1 B‐ and I‐lines was significantly higher with modified Calgary PLUS compared with VetBLUE, with 17 (26.6%) and 42 (65.6%) versus nine (14.1%) and 34 (53.1%) cats identified, respectively. Z‐lines were identified in 62 (96.9%) cats regardless of the protocol used. Three (4.7%) cats had ≥1 B‐line at the subxiphoid view. Conclusions B‐lines were detected in <30%, I‐lines in >50%, and Z‐lines in >95% of clinically healthy cats regardless of protocol used. B‐lines were rarely detected at the subxiphoid view. A significant difference between protocols was found when comparing the percentage of cats with B‐ and I‐lines.