Age-related tendinopathy is common in both humans and horses; the initiation and progression of which is similar between species. The majority of tendon injuries occur to high-strain energy storing tendons, such as the human Achilles tendon and equine superficial digital flexor (SDFT). By contrast, the low-strain positional human anterior tibialis tendon and equine common digital extensor (CDET) are rarely injured. It has previously been established that greater extension occurs at the fascicular interface in the SDFT than in the CDET; this may facilitate the large strains experienced during locomotion in the SDFT without damage occurring to the fascicles. This study investigated the alterations in whole tendon, fascicle and interfascicular mechanical properties in the SDFT and CDET with increasing age. It was hypothesised that the amount of sliding at the fascicular interface in the SDFT would decrease with increasing horse age, whereas the properties of the interface in the CDET would remain unchanged with ageing. Data support the hypothesis; there were no alterations in the mechanical properties of the whole SDFT or its constituent fascicles with increasing age. However, there was significantly less sliding at the fascicular interface at physiological loads in samples from aged tendons. There was no relationship between fascicle sliding and age in the CDET. The increase in stiffness of the interfascicular matrix in aged SDFT may result in the fascicles being loaded at an earlier point in the stress strain curve, increasing the risk of damage. This may predispose aged tendons to tendinopathy.

Summary Reasons for performing study: Subchondral cystic lesions of the medial femoral condyle (SCMFC) are well documented in horses 3 years; arthroscopic debridement or enucleation of the cyst is currently the surgical treatment of choice. However, studies of occurence and outcome following surgery in older horses are lacking. Objective: To identify factors important in outcome for horses with SCMFC treated by arthroscopic debridement. Hypothesis: Age of horse at presentation has a significant influence on return to work following arthroscopic treatment for SCMFC. Clinical and diagnostic findings are also significant with respect to prognosis. Methods: A retrospective review of medical records from 6 equine referral centres identified 85 horses that underwent arthroscopic debridement of SCMFC. Clinical examination, radiographic and arthroscopic findings were analysed together with follow‐up data. Univariable analysis and multivariable logistic regression models were used to determine factors affecting return to soundness. Event‐time analysis was performed to evaluate return to work. Results: Older horses (>3 years) were less likely to return to soundness (P = 0.02) or to work (P = 0.04) than younger horses (> 3 years). Of 39 horses age 0‐3 years, 25 (64%, 95% CI 49‐79%) returned to soundness. Of 46 horses age >3 years, 16 (35%, 95% CI 21‐49%) returned to soundness. In addition, cartilage damage at sites other than the SCMFC negatively affected prognosis (P = 0.05). The hospital where treatment was performed had no influence on return to soundness. Conclusions: Older horses carry a worse prognosis for both return to soundness and return to work. Potential relevance: It is important for clients to be made aware of the difference in outcome between age groups.

A nine-year-old Shetland pony gelding, with a history of recurrent upward fixation of the patella, suddenly developed severe lameness in its right hindlimb. A luxation of the coxofemoral joint was diagnosed by a clinical and radiographic examination. The initial treatment of the luxation by closed reduction was not maintained, and the limb was placed in an Ehmer sling for four days after a second closed reduction. This allowed the femoral head to remain in the acetabulum, although a persistent subluxation remained, presumably owing to a rupture of the round ligament. The pony remained comfortable at pasture for over two years after the reduction, until osteoarthritis of the coxofemoral joint caused it to become severely lame and it had to be euthanased.