The prognosis for long-term survival after surgical bypass of pyloric obstruction is excellent. The overall prognosis for long-term survival after surgical bypass of duodenal obstruction is fair but should be considered guarded in those with pre-existing duodenal adhesions.

Background Supporting limb laminitis (SLL) is suspected to be caused by lamellar ischaemia as a consequence of increased mechanical load. Objectives Examine the effects of prolonged preferential weight bearing (PWB) on lamellar perfusion and metabolism. Study design In vivo experiment. Methods Microdialysis probes were inserted in the lamellar and sublamellar dermis of one forelimb in 13 Standardbred horses. In six horses, a platform shoe (contralateral forelimb) was used to induce increased load on the microdialysis‐instrumented forelimb (PWB). The remaining seven horses were controls (CON). All horses were housed in stocks with limb weight distribution logged continuously for 92 hours. Microdialysate was collected and analysed every 4 hours for glucose, lactate, pyruvate, and lactate to pyruvate ratio (L:P). Microdialysis urea clearance was used to estimate lamellar perfusion. Data were analysed using a mixed‐effects linear regression model. Results Median [IQR] load on the microdialysis‐instrumented limb was equivalent to 38.7% bwt. [37.3‐40.3] in PWB and 27.3% bwt. [26.6‐28] in CON. Limb offloading frequency increased in CON (P < .001) but not PWB (P = .2). Lamellar microdialysate glucose decreased in PWB (P < .001) and CON (P = .004), however, the rate of decrease was higher in PWB (P = .007). Lamellar L:P increased in PWB (P < .001) and peaked at 196 [79‐656], whereas L:P did not change over time in CON (P = .6) and peaked at 42 [41‐49]. Lamellar urea clearance decreased in PWB (P < .001) but not in CON (P = .3). Sublamellar L:P and urea clearance did not change over time in either group (P > .05). Main limitations The PWB model may not be representative of naturally occurring SLL. Conclusions Evidence of lamellar ischaemia (increased L:P and decreased urea clearance) was detected exclusively in the lamellar dermis of PWB feet subjected to persistently increased load. Lamellar ischaemia is a consequence of increased mechanical load and likely contributes to the development of SLL.

Summary This article describes the occurrence of bilateral dentigerous cysts in a 1‐year‐old entire male Standardbred horse. Computer tomography (CT) with a positive contrast CT fistulogram was used to accurately define the anatomy of the cysts preoperatively. Conventional surgical techniques were used to remove the cysts under general anaesthesia. The CT studies were able to precisely define the margins of the cysts and facilitated uncomplicated surgical excision. Follow‐up examination of the animal revealed excellent cosmesis at the surgical site. Histology was used to confirm the diagnosis of bilateral dentigerous cysts. Preoperative CT studies are invaluable to precisely define the anatomical locations of the dental anomalies associated with dentigerous cysts and thereby allow confident and uncomplicated excision. Dentigerous cysts may occur bilaterally in horses.

Objective: To describe a surgical technique for rostral mandibulectomy and reconstruction of the mandibular symphysis. Study design: Case report. Animal: One 5-month-old warmblood cross filly. Methods: A preoperative diagnosis of a juvenile ossifying fibroma was made on the basis of clinical appearance and was later confirmed via histology. The tumor was large, rapidly growing and extending to the caudal aspect of the mandibular symphysis. Computed tomography was performed for surgical planning. The tumor was excised by performing a mandibulectomy caudal to the symphysis. The mandibular symphysis was reconstructed with String of Pearls (SOP) plates. Cortex screws placed in lag fashion, a cortical bone graft from one of the mandibles and a cancellous graft harvested from the tuber coxae. Results: At 9 months of age there was no sign of tumor reoccurrence, the implants were removed because of infection and the mandible had formed a new stable symphysis. The horse was able to prehend food and masticate normally. The owner was pleased with the cosmetic and functional outcome. Conclusion: The described surgical technique is a viable option for mandibulectomy and reconstruction of the mandibular symphysis. The technique provided adequate stability for healing to occur in the face of infection. Clinical significance: Neoplasia and other conditions affecting the entire mandibular symphysis can be treated by complete surgical excision and reconstruction.

RDC resection and bypass may be an alternative approach for management of horses with right dorsal colitis.

Intra‐articular (IA) hyaluronic acid (HA) is commonly used to treat equine arthritis. Inflammatory response or “joint flare” is a recognized potential side effect. However, the incidence and severity of inflammation following IA HA injection in horses is not well documented. This study compared the effects of two IA HA formulations of different molecular weight (MW) and a saline control on clinical signs and synovial fluid markers of inflammation in normal equine joints. Eight adult horses each had three healthy fetlock joints randomly assigned to treatment with either 1.4 mega Dalton HA, 0.8 mega Dalton HA or saline control once weekly for three weeks. Clinical evaluation and synovial fluid analysis were performed by blinded assessors. Outcomes of interest were lameness score, joint effusion score and synovial fluid white cell count and differential, total protein, viscosity and serum amyloid A. Joints injected with HA developed significant mild‐to‐moderate inflammatory responses often associated with lameness and joint effusion compared with saline control joints. The higher MW HA formulation elicited a significantly greater inflammatory response than the lower MW HA after the first injection. In HA injected joints, viscosity remained poor for the entire study. Both IA HA formulations in this study induced an inflammatory response in healthy equine joints. This may have implications for the use of HA in equine joints. The findings in this study are limited to the two HA formulations used. Further investigation of different HA formulations and the use of HA in normal and arthritic equine joints is warranted.

Summary A 24‐hour‐old Standardbred filly was referred with an acute history of weakness, respiratory distress and subcutaneous emphysema. Radiographic evaluation revealed left sided rib fractures, unilateral pneumothorax and pneumomediastinum. Serial arterial blood gas measurements pre‐ and post rib repair showed pulmonary dysfunction. Post operative radiographs revealed the presence of air bronchograms and a bronchointerstitial pattern, suggestive of alveolar parenchymal pathology consistent with pulmonary contusion, pulmonary oedema or ALI/ARDS. The filly was treated with intranasal oxygen and an active chest draining unit and recovered uneventfully.

SGT fractures of various durations can be repaired in a wide range of horses with transversely positioned LCPs, and allow return to athletic function.