High-resolution ultrasonography of experimentally induced full-thickness canine skin wounds: Efficacy in imaging canine skin and comparison of 2 methods of measuring wound size

The aim of the study was to demonstrate the ability of high-resolution ultrasonography (HRU) to image crusted canine wounds and compare 2 methods of evaluating wound area. The dorsal thoracolumbar areas of 10 beagle dogs were clipped, and 2 rows of 6 full-thickness punch 5mm biopsy samples were taken from either side of the midline under general anesthesia. Wounds were allowed to heal by secondary intention, while treatment gel containing an aliamide mast cell modulator, adelmidrol, or gel base was applied twice daily to randomly selected treatment and control groups. Concentric 8mm punch biopsy samples of the healing wounds were taken on Days 1, 2, 4, 8, and 14 for histopathological assessment. Wounds were imaged until the second biopsy with 20MHz HRU daily for 28 days. High-resolution ultrasonography proved to be quick and easy to use on canine skin and generated images of the dermis beneath crusts and healing epidermis suitable for analysis. Wound morphometry was performed on the digital HRU images (diameter and depth of wound; number of pixels in the wound area). The measurements were used for the calculation of wound area. A Bland-Altman plot was constructed. Least products regression was used to test for the presence of fixed and proportional bias between the 2 methods. There was an increase in the difference between the 2 methods as the measured area increased. Visual appraisal of the Bland-Altman plot suggested the presence of proportional bias, and this was confirmed using least products regression. Repeated measures analysis of variance identified a significant change in wound area over time for both methods but identified a significant difference between treated and control animals for the pixel method only. Both methods appear suitable for assessment of wound area over time, but the pixel method appears to be more accurate.