Ultrasonographic evaluation of collateral ligaments of the distal interphalangeal joint in Quarter Horse forelimbs

Thirty non-lame Quarter Horses under athletic exercise training, aged between 2 and 23 years old, both males and females were evaluated in order to find ultrasonographic characteristics of distal interphalangeal joint’s (DIPJ) collateral ligaments (CLs) in their forelimbs. The horses were divided into three groups based on age. Group A consisted of horses aged between three and four years old; group B consisted of equines aged between five and ten years old; and group C consisted of animals that were over ten years old. Six parameters were assessed, including increase of the ligament area (LA), hypoechogenicity (HO), collapse of coronal vessels (CV), heterogeneity (HT), hyperechogenicity (HR) and irregularity of ligament borders (IB). Older horses were more prone to displaying ultrasonographic alterations in the CL-DIPJ. The prevalent ultrasonographic findings observed were alterations in the echogenicity of the fibers and ligament thickening, diagnosed in 73,33% (88/120) of the examined ligaments. The medial collateral ligament (MCL) displayed more frequent alterations than the lateral collateral ligament (LCL). In conclusion, this study provided a detailed characterization of the ultrasound examination of the CL-DIPJ in the forelimbs of clinically non-lame Quarter Horses subjected to intensive exercise routines. The findings demonstrate that even in non-lame horses, ultrasonographic alterations can be observed in the CL-DIPJ.