18F-sodium fluoride positron emission tomography provides pertinent additional information to computed tomography for assessment and management of tarsal pain in horses.

OBJECTIVE: To assess the value of 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) for imaging the tarsus and proximal metatarsus and compare it with CT and lameness evaluation. ANIMALS: 25 horses with lameness localized to the tarsal and proximal metatarsal regions that underwent 18F-NaF PET/CT between 2016 and 2021. METHODS: 18F-NaF PET and CT images were retrospectively independently evaluated by 3 observers. Standardized uptake values (SUV) were used to characterize 18F-NaF uptake. Correlation between PET and CT findings with subjective and objective maximum (Max-D) and minimum pelvic height lameness data was estimated. RESULTS: The inter-observer Kappa-weighted value (κ) was higher for PET (κ = 0.66) than CT (κ = 0.6). CT and PET scores were fairly correlated (R = 0.49; P < 0.05). PET SUVratio (SUV of the main lesion/SUV talus) had the highest correlation with Max-D (R = 0.71; P < .05). PET and CT scores for the plantar region were significantly higher in Quarter Horses (P < .05) and showed consistently higher correlation with objective lameness data (CT plantar grade - Max-D [R = 0.6; P < .05], PET plantar grade - Max-D [R = 0.47; P = .04]) than other regions of the distal tarsal joints. Three Warmbloods presented marked uptake at the medial cochlea of the distal tibia. CLINICAL RELEVANCE: PET had a moderate correlation with CT for assessment of tarsal lesions. The degree of PET uptake can help differentiate active versus inactive lesions. Specific location of the uptake is important in determining clinical relevance.

Establishment of a sequential dual tracer 18 F-NaF/18 F-FDG PET protocol for imaging the equine foot.

The combination of 18 F-Sodium Fluoride (18 F-NaF) and 18 F-FluoroDeoxyGlucose (18 F-FDG) for positron emission tomography (PET) imaging of the equine foot is appealing for detection of both osseous and soft tissue lesions in a single scan. As the combination of tracers could lead to a loss of information, a sequential approach, consisting in imaging with one tracer prior to injecting the second tracer, might be valuable. The goals of this prospective, methods comparison, exploratory study were to establish the order of tracer injection and timing for imaging. Six research horses were imaged under general anesthesia with 18 F-NaF PET, 18 F-FDG PET, dual 18 F-NaF/18 F-FDG PET, and CT. Proper uptake could be identified in tendon lesions as early as 10 min after 18F-FDG injection. Bone uptake was limited when 18F-NaF was injected under general anesthesia, even at 1 h after injection, when compared with 18 F-NaF injection prior to anesthesia. The sensitivity and specificity of the dual tracer scans were 0.77 (0.63 to 0.86) and 0.98 (0.96 to 0.99) respectively, to assess 18 F-NaF uptake and 0.5 (0.28 to 0.72) and 0.98 (0.95 to 0.99), respectively, for 18F-FDG uptake. These results suggest that the sequential dual tracer approach is a pertinent technique to optimize the PET data gained from a single anesthetic episode. Based on dynamics of tracer uptake, the optimal protocol consists in injecting 18F-NaF prior to anesthesia, acquire 18F-NaF data then inject 18F-FDG and start acquisition of dual tracer PET data 10 min later. This protocol should be further validated in a larger clinical study.

Medial malleolus fragmentation following talocalcaneal arthrodesis by a dorsomedial approach in a horse.

A 16-year-old, Quarter Horse mare was presented for a 3/5 right hind lameness associated with osteoarthritis of the talocalcaneal joint (TCLJ). Positron emission tomography (PET) and computed tomography (CT) demonstrated marked increased uptake of 18F-sodium fluoride and bone remodeling at the medial facet of the TCLJ, respectively. Under general anesthesia 2 cortical screws (4.5 and 5.5 mm) were placed in neutral fashion via an arthrotomy from dorsomedial to plantaromedial through the medial facet of the TCLJ followed by copious lavage of the tarsocrural joint. Eight weeks after surgery, observable effusion of the tarsocrural joint was present and lameness had worsened. Radiographic examination revealed a fragmented medial malleolus of the tibia, likely secondary to repetitive trauma of the screw heads during tarsal flexion. Repeated CT showed partial fusion of the TCLJ. Both screws were removed and the tarsocrural joint was thoroughly lavaged arthroscopically. At a 20-month recheck the lameness had not improved, and ultrasound examination revealed severe thickening of the TCLJ capsule. Recheck examination 48 mo after surgery showed complete fusion of the TCLJ and resolution of the lameness. Key clinical message: Diagnosis of osteoarthritis of the TCLJ is challenging. Management by arthrodesis using a dorsomedial approach can result in fragmentation of the medial malleolus, with secondary synovitis and capsulitis of the tarsocrural joint.

Fragmentation de la malléole médiale suite à une arthrodèse talo-calcanéenne par voie dorsomédiale chez un cheval. Une jument Quarter Horse âgée de 16 ans a été présentée pour une boiterie postérieure droite de 3/5 associée à une arthrose de l'articulation talo-calcanéenne (TCLJ). La tomographie par émission de positrons (TEP) et la tomodensitométrie (CT) ont démontré une augmentation marquée de l'absorption du fluorure de sodium-18F et un remodelage osseux significatif au niveau de la facette médiale du TCLJ, respectivement. Sous anesthésie générale, deux vis corticales (4,5 et 5,5 mm) ont été placées de façon neutre via une arthrotomie dorsomédiale à plantaro-médiale à travers la face médiale du TCLJ suivie d'un lavage abondant de l'articulation tarsocrurale. Huit semaines après la chirurgie, un épanchement significatif de l'articulation tarso-crurale était présent et la boiterie s'était aggravée. L'examen radiographique a révélé une malléole médiale du tibia fragmentée, probablement secondaire à un traumatisme répétitif des têtes de vis lors de la flexion du tarse. La tomodensitométrie répétée a montré une fusion partielle du TCLJ. Les deux vis ont été retirées et l'articulation tarso-crurale a été soigneusement lavée par arthroscopie. Lors d'un nouveau contrôle après 20 mois, la boiterie ne s'était pas améliorée, et l'échographie a révélé un épaississement sévère de la capsule TCLJ. Un nouvel examen 48 mois après la chirurgie a montré une fusion complète du TCLJ et une résolution de la boiterie.Message clinique clé :Le diagnostic de l'arthrose du TCLJ est difficile. La prise en charge par arthrodèse par voie dorso-médiale peut entraîner une fragmentation de la malléole médiale, avec synovite secondaire et capsulite de l'articulation tarso-crurale.(Traduit par Dr Serge Messier).

Factors affecting successful ultrasound-guided injection into the podotrochlear bursa using a palmarolateral approach.

OBJECTIVE: To evaluate potential factors affecting ultrasonographic visibility of the suprasesamoidean region and the success rate of ultrasound-guided injection (USGI) into the podotrochlear bursa (PB). STUDY DESIGN: Ex vivo, experimental study. ANIMALS: 24 cadaveric forelimbs. METHODS: The PB was distended with 0, 1, or 2 ml of iodinated contrast material and saline under radiographic guidance. Ultrasonographic visibility of the suprasesamoidean region and PB was graded before and after distention with the limb loaded in three positions (vertical, cranial and caudal). Two operators with different experience levels performed an USGI into the PB with methylene blue (12 limbs each [four limbs with each of three volumes of PB distension]) using a palmarolateral approach and caudal foot placement. Limbs were frozen and sectioned to assess accuracy. RESULTS: Ultrasonographic visibility scores of the suprasesamoidean region (p = .0081) and PB (p < .0001) were improved using a caudal foot placement. Higher visibility grades of the suprasesamoidean region were associated with higher injection success rate (p = .047). The injection success was 75% (9/12) for the experienced versus 41.6% (5/12) for the less experienced operator (p = .14). PB distension improved visibility during caudal foot placement (p = .013) but not injection success rates (p = .78). CONCLUSION: Caudal foot placement enhances visibility of the PB and suprasesamoidean region. Limbs with poor visibility of the suprasesamoidean region are more likely to undergo a failed USGI. CLINICAL SIGNIFICANCE: The lateral USGI approach should be performed only in cases of optimal visibility. The reported success rates support the technical challenge of PB injections.

Radiological prevalence of osteoarthritis of the cervical region in 104 performing Warmblood jumpers.

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.

Preoperative factors associated with resection and anastomosis in horses presenting with strangulating lesions of the small intestine.

OBJECTIVE: To determine if preoperative and intraoperative clinical variables correlate with resection and anastomosis (RA) in horses presenting with strangulating small intestinal (SI) lesions. STUDY DESIGN: Retrospective case series. ANIMALS: Horses undergoing exploratory celiotomy for a strangulating SI lesion (n = 243). METHODS: The records of horses undergoing surgical correction for strangulating SI lesions from January 1, 2000 to December 31, 2017 were reviewed. Horses were categorized as treated with RA or not treated with RA. Obtained information included history, signalment, clinical findings, diagnostic test results, intraoperative findings, and survival to discharge. Univariable and multivariable analyses were used to compare data between horses treated with RA vs those not treated with RA (P = .05). RESULTS: In total, 172 SI lesions were resected, and 71 were not resected. Horses that had gastric reflux at admission to the hospital (odds ratio [OR] 5.56; 95% CI 1.76, 17.59) and horses with amotile SI according to abdominal ultrasonography (OR 9.69; 95% CI 3.09, 30.37) were more likely to undergo RA. Increased difference between peritoneal fluid and blood lactate was higher in horses that underwent RA (OR 1.55; 95% CI 1.12, 2.13). Survival to hospital discharge was lower in the group of horses that underwent RA compared with horses that did not undergo RA. CONCLUSION: Resection and anastomosis of strangulating SI lesions was associated with several preoperative variables. CLINICAL SIGNIFICANCE: This study highlights the value of preoperative diagnostic procedures in aiding intraoperative decision making and prognostication in horses presenting with strangulating SI lesions.

The prevalence of temporal bone fractures is high in horses with severe temporohyoid osteoarthropathy.

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.

Arthroscopic removal of osteochondral fragments in the dorsal pouch of the proximal intertarsal joint in 29 horses.

OBJECTIVE: To describe the radiographic and surgical findings of horses with osteochondral fragments (OCF) in the proximal intertarsal joint (PIJ) and to detail the technique for arthroscopic fragment retrieval and report outcomes. STUDY DESIGN: Retrospective case series. ANIMALS: Twenty-nine horses (32 tarsi) with OCF in the PIJ. METHODS: Medical records of horses with radiographic evidence of OCF in the PIJ were reviewed. Clinical features, number of fragments, location, arthroscopic appearance, and outcome were recorded. Technical modifications with visual aids specific to this arthroscopic technique are described. RESULTS: Twenty-seven horses (93%) had radiographic evidence of osteochondritis dissecans lesions in the tarsocrural joint (TCJ). OCF were most commonly located distal to the medial trochlear ridge of the talus. In all cases, fragments were successfully retrieved with a technique based on exposing the fragments after resection of the proximal intertarsal joint capsule (PIJC). Fragments were visible from the TCJ prior resection of the PIJC in 4 of 32 tarsi. A third portal was created to access fragments located distal to the lateral trochlear ridge in 3 of 32 tarsi. Moderate intra-articular bleeding occurred when the PIJC was resected in 3 of 32 tarsi. One horse had postoperative swelling that resolved with conservative medical management. All horses with long-term follow-up available (16/29) started training or returned to their athletic career. CONCLUSION AND CLINICAL SIGNIFICANCE: 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.