Proximal Suspensory Desmopathy in Hindlimbs: A Correlative Clinical, Ultrasonographic, Gross Post Mortem and Histological Study

Abstract

Reasons for performing studyIt has been suggested that ultrasonography is unreliable for the detection of hindlimb proximal suspensory desmopathy (PSD) based on comparison between ultrasonographic and magnetic resonance images.ObjectivesTo compare ultrasonography with gross and histopathological post mortem examination in horses with PSD diagnosed based on the response to local anaesthesia and ultrasonography.Study designRetrospective study.MethodsNineteen horses with hindlimb PSD were humanely destroyed. The ultrasonographic abnormalities were graded prospectively as mild, moderate or severe based on predefined criteria. Thirty‐seven lame limbs were examined grossly and 36 suspensory ligaments (SLs) were examined histologically. The histological images were graded blindly based on predefined criteria (0–3 for each tissue type; 0 = normal, 3 = severe abnormality). Descriptive statistics were performed.ResultsUltrasonographic lesions were graded moderate in 31/38 (81.6%) and severe in 7/38 (18.4%) limbs; in 4/36 (11.1%) limbs adhesion formation between the proximal aspect of the SL and the accessory ligament of the deep digital flexor tendon was predicted. Gross post mortem examination revealed substantial adhesions between the proximal aspect of the SL and adjacent soft tissues in 10/37 (27.0%) limbs; in 10/37 (27.0%) limbs there were adhesions between the body of the SL and the mid plantar aspect of the third metatarsal bone, extending distally in 6 (16.2%) limbs. Histology revealed abnormalities (grades 1–3) of the collagenous tissue in 25/36 (69.4%) limbs. Muscle was abnormal (grades 1–3) in 35/36 (97.2%) limbs and adipose tissue (grades 1–3) in 16/36 (44.4%) limbs. Neural abnormalities (grades 1–3) were seen in 23/36 (63.9%) limbs and vascular changes (grade 1 and 2) in 2/36 (5.6%) limbs. In 1/36 limbs no abnormality was detected.ConclusionsUltrasonography was reasonably reliable for the detection of SL pathology based on histology as a gold standard, but the ability to detect gross adhesions was limited.Ethical animal research: The study was approved by the Ethical Review Committee of the Animal Health Trust and had informed consent of the owners. Source of funding: None. Competing interests: None declared.