F-NaF PET imaging of the Thoroughbred fetlock is feasible and compares favourably with other imaging modalities in detecting stress remodelling in Thoroughbred racehorses. PET appears to be a beneficial imaging modality when used for early detection of stress remodelling in an effort to prevent catastrophic musculoskeletal injuries in this population of horses.

Background Cervical osteoarthritis (OA) has been documented as a potential source of pain and poor performance in sport horses. Objectives To assess the prevalence of cervical OA in a population of Warmblood jumpers and its correlation with age, level of performance, neck pain and mobility. Study design Descriptive observational study. Methods Warmblood jumpers free of lameness or neurological disorders were selected. Cervical pain and range of motion of the neck were subjectively assessed. Left to right lateral views were taken at C3‐C4, C4‐C5, C5‐C6 and C6‐C7. The presence of OA at the cervical articular process joints (APJs) was evaluated and graded as absent, mild or moderate to severe by three board‐certified radiologists. The agreement between radiologists and the potential associations between OA grades with age and other variables were statistically assessed (P < .05). Results One hundred and four horses were included [median age = 10 years (range 6‐18 years)]. Agreement between radiologists varied from fair to substantial (Kappa‐weighted 0.37‐0.61). The C6‐C7 APJ was most commonly affected by OA with only 32.7% of APJ considered free of radiographic abnormalities at this location versus 60.5% at C5‐C6, 81.7% at C4‐C5 and 84.6% at C3‐C4. Horses competing in higher level classes (peak of performance) had significantly higher OA grades at C6‐C7 (P = .013). There was no association between age, age when started jumping, neck pain and neck range of motion with the presence of OA on radiographs. Main limitations Open enrolment and lack of orthogonal views. Conclusions This study showed that, although there is a range of interpretation of radiographic findings of the APJ, OA of the caudal cervical region is not rare in performing sound Warmblood jumpers. This suggests that OA in the caudal cervical region may be of low clinical significance.

Summary Background A technique for intra‐arterial injection of mesenchymal stem cells (MSC) has been established for front limbs with the use of the median artery. This approach has been proposed for treatment of soft tissue injuries of the equine distal limb. A technique has not been validated yet for hindlimb injection. Objectives To assess the feasibility of injection of the cranial tibial artery in horses, and to evaluate the distribution and persistence of MSC after injection. Study design In vivo experiment. Methods In a first phase, the cranial tibial arteries of both hindlimbs of three research horses were catheterised with ultrasound guidance under general anaesthesia and injected with iodinated contrast. In the second phase, iodinated contrast was injected in three standing sedated horses with ultrasound guidance. In the final phase, 99mTechnetium‐HMPAO labelled allogenic bone marrow derived equine MSC were injected under standing sedation with the same technique in three other horses. Scintigraphy was used to assess MSC distribution and persistence for 24 h. Ultrasound was performed 24 h after injection to assess vessel impairment. Results Arterial injection was achieved in all 18 limbs without any significant complications. Mild partial periarterial injection was observed in four limbs. Scintigraphic images demonstrated diffuse MSC distribution from the tarsal area to the foot. Persistence decreased over time but signal was still present at 24 h. Main limitations Limited retention of the radiolabel in the MSC. Conclusions Ultrasound‐guided injection of the cranial tibial artery can be performed both under general anaesthesia and standing sedation in horses. This technique could be used for MSC treatment of equine proximal suspensory desmopathy or other injuries in the distal hindlimb.

Temporohyoid osteoarthropathy is a well-recognized cause of equine neurologic disease. Temporal bone fractures associated with temporohyoid osteoarthropathy have been recognized with CT, however, little information is available regarding these fractures. The aims of this retrospective analytical study were to assess the prevalence of these fractures and to describe the specific configurations and associated imaging and clinical features. Fracture of the temporal bone was identified with CT in 16 of 39 included horses. All fractures were unilateral, minimally displaced and extended through the temporal bone in a rostrodorsal to caudoventral orientation. Two fracture configurations were identified: in nine cases, the fracture extended the full width of the petrous pyramid into the cranial vault and in seven cases, the fracture only extended through the lateral part of the petrous temporal bone, not involving the cranial vault. Fusion of the temporohyoid joint was present in 13 of the 16 fracture cases. Quarter Horses were over-represented in the fractured population (14/16). All horses with fractures had ipsilateral neurologic deficits. Patient outcomes were not significantly different between temporohyoid osteoarthropathy horses with and without temporal bone fractures (P = 0.68). However, six of the nine patients with cranial vault involvement did not return to their previous use. Findings support previous studies indicating that temporal bones should be carefully assessed for concurrent fractures when temporohyoid osteoarthropathy is identified in CT images, especially when there is fusion of the temporohyoid joint. An improved awareness of specific fracture configurations will help with detection of these fractures. K E Y W O R D Scomputed tomography, cranial nerves, facial paralysis, neurology, vestibular syndrome

The arthroscopic technique based on resection of PIJC was effective in retrieving OCF in the PIJ and was associated with minor complications. The clinical relevance of these fragments in the PIJ remains unknown.