Maxime Vandersmissen

Standing low-field magnetic resonance imaging (MRI) is widely used for subchondral bone (SCB) assessment of the equine proximal phalanx, but radiography remains the most common first-line imaging modality, and no direct comparison between the two is available for SCB sclerosis and resorption. Fifty-four fetlocks from 52 horses referred for standing MRI were retrospectively assessed at the medial glenoid, sagittal groove and lateral glenoid, using an ordinal scale for sclerosis and a four-type nominal classification for resorption. Seven readers of varied clinical backgrounds performed independent radiographic readings; two board-certified radiologists then established a consensus reading, blinded to MRI. Agreement was quantified with Gwet’s agreement coefficients (inter-reader), weighted and unweighted Cohen’s κ (reader-MRI) and symmetric metrics (consensus-MRI). Inter-reader agreement for sclerosis was location-dependent (Gwet’s agreement coefficient = 0.27–0.73, lowest medially) and substantial-to-almost-perfect for resorption (Gwet’s agreement coefficient ≥ 0.72). The radiographic consensus aligned closely with MRI at the sagittal groove but underestimated marked sclerosis medially and over-called it laterally; fracture-type resorption was reliably detected at the sagittal groove but misclassified medially. Radiography can be relied upon for sagittal groove lesions, but complementary MRI is warranted medially when resorption or clinical suspicion of fracture is present, and to confirm radiographic positive calls laterally.

Mesenchymal stromal/stem cells (MSCs) are increasingly investigated as intra-articular therapies for equine osteoarthritis (OA), although most studies have focused on allogeneic or combination-based approaches. Evidence supporting the use of autologous MSCs as a stand-alone treatment remains limited. The present study evaluated the safety and clinical evolution following intra-articular administration of autologous muscle-derived MSCs (mdMSCs) in horses with naturally occurring chronic OA. Thirteen horses with confirmed clinical disease were included. Each affected joint received a single injection, with the administered cell dose adapted to joint size (1 × 10⁷ or 2 × 10⁷ cells). Clinical assessments were conducted at baseline and at 6 and 12 weeks post-treatment using the American Association of Equine Practitioners (AAEP) lameness scale, together with a joint inflammation score and a composite total clinical score (TCS). Clinical scores decreased over time, with statistically significant improvements observed at both follow-up time points. Seven of thirteen horses met the predefined responder criteria based on AAEP improvement, including complete resolution of lameness in several cases. The treatment was well tolerated, with only mild and transient local reactions that resolved without intervention. These results indicate that intra-articular administration of autologous mdMSCs is associated with clinically relevant improvement in horses with chronic OA.

Tendon and ligament injuries are frequent in sport horses and are prone to recurrence due to incomplete healing. Platelet-rich plasma (PRP) and mesenchymal stem cells (MSCs) are increasingly used, but data controlled on the early effects of autologous MSCs remain limited. A prospective randomized, double-blind, placebo-controlled trial was conducted in horses with naturally occurring tendinopathies. After standardized PRP pretreatment, non-responders were randomized to receive intralesional autologous muscle-derived MSCs (mdMSCs, n = 17) or placebo (n = 6). Clinical and ultrasonographic parameters were evaluated at the recruitment period (T0) before the administration of the local treatment (T1), 4 (T2) and 8 weeks later (T3). Eighteen horses from both groups received at T2 a second intralesional injection of mdMSCs at the investigator’s discretion; this phase was not randomized. Horses treated with mdMSCs showed significant improvements from T1 to T2 across both clinical and ultrasonographic parameters, whereas no significant changes were observed in the placebo group. Between-group comparison at T2 confirmed the significant superiority of mdMSCs. Further improvements were observed between T2 and T3 in the 18 horses that received a second injection. No systemic adverse events were recorded, and local reactions were mild and transient. This randomized controlled trial demonstrates early clinical and ultrasonographic efficacy of autologous mdMSCs in equine tendinopathy, with additional benefit from a second injection. The autologous approach combines efficacy and safety while avoiding the immunological and logistical constraints of allogeneic strategies.

Summary: Background: While standing magnetic resonance imaging (sMRI) of the foot has been extensively studied, descriptions of cone beam computed tomography (CBCT) abnormalities in this region are sparse. Objective: This study compares CBCT and sMRI for diagnosing lesions in the equine foot and pastern, aiming to assess the complementarity of these imaging modalities. Study Design: This is a retrospective, descriptive, comparative study. Methods: CBCT and sMRI images of horses that underwent dual imaging between September 2023 and September 2024 were reviewed to evaluate the complementarity of both techniques. Results: Seventy‐five feet of 59 horses were included. CBCT and sMRI provided complementary diagnostic information. CBCT was particularly effective in identifying changes in bone structure, soft tissue mineralisation and hoof wall abnormalities. In contrast, sMRI was superior in detecting soft tissue injuries and bone marrow oedema‐like signals. Compared with sMRI used alone, CBCT provided additional diagnostic information that enhanced diagnostic accuracy in 71% of cases. Main limitations: No gold standard (i.e., post‐mortem findings) was available as the horses were client owned. Conclusions: This study highlights the strengths and limitations of CBCT and sMRI in diagnosing equine foot and pastern pathologies. In most cases, CBCT provided additional information on conditions already visible on sMRI; however, it also detected abnormalities unidentified by sMRI in horses with osteoarthritis, subchondral bone lesions or hoof wall abnormalities.

This retrospective study aims to describe baseline and follow‐up imaging findings in subchondral and trabecular bone damage occurring outside of the sagittal groove in the proximal phalanx (P1) glenoid in a case series of lame Warmblood horses. Thirteen lame horses (16 forelimbs) with standing magnetic resonance imaging (sMRI) evidence of nonsagittal groove glenoid subchondral and trabecular bone injury of P1 as the main lesion were included. All injuries were located at the medial aspect of the P1 glenoid. At sMRI, changes included subchondral bone plate thickening and trabecular sclerosis, bone marrow edema‐like signal, subchondral bone resorption (11/16), and new bone production (8/16). Subchondral bone resorption in the transverse plane was linear (8/11), round (2/11), or ill‐defined (1/11). Sclerosis, bone resorption, and new bone production were seen radiographically in 10, 4, and 5 limbs, respectively. All limbs had concurrent metacarpal condyle sMRI imaging abnormalities, osteophytosis, and joint effusion. Follow‐up sMRIs were obtained in 8 of 16 limbs, five of which showing progression of the resorptive lesion. One horse encountered a comminuted fracture of the affected P1 18 months after the follow‐up sMRI examination. The imaging appearance of the medial glenoid bone injuries of P1 in this case series is consistent with chronic bone overload. The linear configuration of bone resorption seen in eight lesions suggests short, incomplete stress fractures, which is supported by the ultimate catastrophic fracture occurring in one case.

Les lésions sous-chondrales de la phalange proximale peuvent affecter la portion médiale de la cavité glénoïdale. Lorsqu’une lésion est suspectée à cette localisation, une incidence radiographique dorso15-30° latérale-palmaromédiale oblique peut être réalisée pour faciliter la détection d’une réaction périostée, qui pourrait signer un cal osseux et donc la présence d’une fracture de fatigue. Même en cas de lésion radiographique visible, l’examen IRM est indiqué pour préciser la configuration de la lésion sous-chondrale et son degré d’activité.

Summary: Background: Lymph nodes are routinely assessed ultrasonographically in humans and small animals. The ultrasonographic assessment of equine lymph nodes has only been sporadically reported. Objectives: The aims of this study were to establish anatomical landmarks, ultrasonographic technique and normal ultrasonographic appearance of clinically relevant equine lymph nodes difficult to assess by palpation and to provide a useful reference for equine practitioners. Study design: This was prospective observational study. Methods: Medial retropharyngeal, cranial and caudal deep cervical, and caecal lymph nodes were visualised using transcutaneous ultrasonography in 19 clinically healthy horses, and lymph nodes of the iliosacral lymphocentre were visualised using transrectal ultrasonography in nine horses with no metabolic or infectious disorders. Anatomical landmarks, size and echogenicity were recorded. Results: A total of 268 lymph nodes were visualised and measured in 25 horses. Lymph nodes were ovoid with regular contour and homogeneous parenchyma, hypoechoic to isoechoic to the surrounding tissue. The visualised lymph nodes of the sacroiliac lymphocentre were the smallest (mean ± standard deviation: 2.4 ± 0.9 × 5.9 ± 1.8 mm), and the largest were the caudal deep cervical lymph nodes (mean ± standard deviation: 5.1 ± 1.9 × 10.9 ± 5.6 mm). The short‐to‐long‐axis ratio varied from 0.44 to 0.60 among the lymph nodes examined. Main limitations: Normality of lymph nodes was not confirmed by histopathology. Conclusions: This study describes the ultrasonographic technique, anatomical landmarks and appearance of presumptively normal medial retropharyngeal, cranial and caudal deep cervical, caecal lymph nodes and caudal lymph nodes of the iliosacral lymphocentre.

Summary: This report outlines the diagnosis, surgical treatment and successful outcome following the treatment of a foal presented with a congenital abdominal hernia. A focal ventral abdominal swelling, enlarging since birth, starting just caudal to the intact umbilicus and extending caudally over the prepuce was observed. Once in dorsal recumbency, the hernia was found to originate from a defect of the abdominal wall in the linea alba region. A simple closed herniorrhaphy with inversion of the large peritoneal sac into the abdomen was performed. Post‐operative complications included fever with the development of an abscess at the surgical site. This was diagnosed and drained with ultrasound guidance. Based on culture and sensitivity testing of the abscess exudate, antibiotic therapy was adapted and the foal made a full recovery. A clinical examination undertaken 1 year later revealed complete healing of the linea alba . Herniation due to a muscle wall default has not been previously reported in foals. This article reviews the commonly observed causes of herniation (umbilical and inguinal hernias). However, a third type of congenital ventral body wall hernia should be considered for the differential diagnosis of swelling of the preputial area in foals.

A 15‐year‐old pony was presented for acute neurological signs. Neurological examination suggested a brainstem lesion, blood laboratory tests detected an active inflammatory process, and upper respiratory endoscopy identified a suppurative lesion at the dorsal aspect of the right guttural pouch. Computed tomography was performed and findings were consistent with pituitary abscess, meningitis, and atlanto‐occipital joint septic arthritis. Imaging findings were confirmed based on cerebrospinal and synovial fluid cultures and necropsy. Computed tomography provided important information for identifying the cause of the patient's neurological signs and helped the owner make a final decision for euthanasia.

Summary: Background: Squamous cell carcinoma is the most common pharyngeal neoplasm but is poorly documented with diagnostic imaging in veterinary literature. Objectives: To describe the diagnostic imaging findings in horses with confirmed pharyngeal squamous cell carcinoma. Study design: Retrospective case series. Methods: Horses with a definitive diagnosis of pharyngeal squamous cell carcinoma based on in situ biopsy and/or cytology were identified in 2 different centres. Multi‐modality imaging findings are reported. Results: Six equids were included. On radiographic examination, increased pharyngeal opacity and reduction of pharyngeal lumen were observed in all horses, centred on the oropharynx (three cases), the laryngopharynx (two cases) or the nasopharynx (one case). A clearly delineated mass was visualised in four cases. Additional radiographic findings were border effacement of the epiglottis (5/6) or soft palate (3/6), thickening of the pharyngeal walls (4/6) or soft palate (3/6) and suspected retropharyngeal lymphadenomegaly (3/6). Ultrasonography was useful to highlight retropharyngeal (4/6) and mandibular (4/6) lymphadenopathy suggestive of metastatic dissemination. Computed tomographic images were available for two horses and detected bone lysis not visible on radiographs. Main limitations: The number of cases was low, and computed tomography was not realised in all cases. Conclusions: Findings support the usefulness of radiography and ultrasonography in horses with suspected pharyngeal neoplasia for a first‐line imaging diagnosis, in particular when endoscopy is impaired by a mass effect or dyspnoea. Computed tomography gives a more accurate assessment of bone involvement.