Ultrasonographic measurement of collateral ligaments of the distal interphalangeal joint in Criollo horses

Abstract

Criollo horses were used in the past only for field services, especially countryside work. However, currently, they have been used as sports animals in several modalities involving turns in legs and exercises on irregular terrain, predisposing them to injuries in the distal extremity. Among the alterations recognized as cause of lameness in this region are the conditions related to collateral ligaments of the distal interphalangeal joint (CL-DIPJ), which in horses are structures that help to maintain joint stability and suffer a high pressure due to the high body weight, especially when it is not equally distributed at the stance phase. Considering the importance of the ultrasound anatomical knowledge of this structure for the early diagnosis of locomotive affections in the digit of Criollo horses, this study aimed to standardize CL-DIPJ measurements in healthy horses of this breed. We used 25 adult Criollo horses not submitted to sports practice. For ultrasonographic evaluation, after a trichotomy of the region, an ultrasound Chison 8300VET and a 6.0 MHz linear probe were used with a standoff pad. This technique uses a cross-sectional view, in which CL-DIPJ is visualized in the distal concavity portion of the middle phalanx, being a standard for the measurements. For ligament measurements, the variables dorsopalmar diameter (DPD), latero-medial diameter (LMD), and cross-sectional area (CSA) of ligaments were used. Three measurements were performed for each variable and average values were obtained, which were compared to each other and did not present significant differences (p > 0.05). The average measurements of diameter and area of collateral ligaments of the distal interphalangeal joint in Criollo horses were 9.04 mm for DPD, 7.55 mm for LMD, and 0.52 mm2 for CSA. This was the first study that standardized the size of this structure in this breed.