Andrea Bertuglia

To report the incidence, and clinical and pathological findings of developmental lateral patellar luxation in Standardbred yearlings diagnosed with femoropatellar dysplasia (FPD) and demonstrate that osteochondral lesions in the lateral trochlear ridge (LTR) of the femur observed in the affected horses are osteochondral lesions related to patellar maltracking. Retrospective case series. Medical records were retrospectively reviewed for Standardbreds <12 months of age diagnosed with FPD between 2017 and 2023. A total of 10 Standardbred yearlings developed FPD (incidence 6.4 cases per 1,000 foals). Patellar instability and femoropatellar joint effusion were observed between 3 and 9 months of age. Six horses developed severe lameness at walk within 6 months from diagnosis. Radiography revealed abnormal patellar tilt in all cases, flattening and osteochondral lesions in the LTR in nine cases, flattening of the intertrochlear groove and patellar ridge in three horses, and patellar displacement in two cases. The condition deteriorated in six cases, leading to euthanasia, while four horses were retired to pasture. FPD is not uncommon in Standardbred yearlings and clinical signs are visible under 12 months of age. The condition is career-limiting and affected horses have poor prognosis despite treatment as racehorses.

Background/Objectives: The equine proximal interphalangeal joint (PIPJ), while often considered a low-motion joint, contributes to flexion/extension of the digit and accommodates multi-planar movements: the adduction/abduction and the internal/external rotation of the middle phalanx in comparison to the proximal phalanx. Its collateral ligaments are primary stabilizers, restricting movements of the equine digit outside the sagittal plane, and their injury often leads to joint instability and degenerative joint disease. End-stage degenerative joint disease in the PIPJ could be managed with surgical arthrodesis of the joint. After surgical arthrodesis of the PIPJ, joint fusion cause loss of PIPJ extension in late stance of the stride during locomotion, which is accommodated by increased extension of the distal interphalangeal joint (DIPJ). To validate joint-preserving repair techniques after a collateral ligament injury in replacement of arthrodesis, a reliable method for assessing PIPJ extrasagittal biomechanics is required. The objective of this study was to develop and validate a three-point bending test setup to quantitatively characterize the mechanical behaviour of the equine PIPJ during abduction/adduction, simulating loading conditions that challenge the collateral ligaments of the joint. Methods: Seven equine PIPJ specimens (five forelimb and two hindlimb) were tested. A customised 3D-printed system was used to stabilise the joints in an MTS testing system. A three-point bending test was performed to evaluate the joint's mechanical response to the mediolateral plane bending. A marker-based video analysis system with a custom MATLAB script was used to calculate the joint abduction/adduction bending angle. Results: The setup provided reproducible load-displacement and time-angle data. The use of a fixed loading rod and custom 3D-printed system minimized slippage and rotation. The forelimb PIPJs exhibited significantly greater maximum medio-lateral bending angles compared to hindlimb joints. No significant differences were observed between fresh and frozen-thawed specimens. Conclusions: The developed three-point bending test setup provides a reliable and reproducible method for the in vitro evaluation of the biomechanical of the equine PIPJ. This study establishes a baseline for healthy joints and is suitable for the future comparative assessment of novel surgical techniques for collateral ligament repair.

Orthotics are often used to support the metacarpophalangeal joint (MCPj) in horses recovering from soft tissue injury; however, their effect on the MCPj biomechanics remain largely underexplored. The MCPj moves primarily in the sagittal plane, flexing during the swing phase and extending during the stance phase. The suspensory ligament and flexor tendons act as biological springs resisting MCPj extension. Injuries to these structures are common and, although early mobilization promotes their healing, controlled loading may be beneficial during rehabilitation. This study aims to evaluate the efficacy of a semirigid orthotic in limiting the MCPj extension and the MCPj range of motion, and its influence on the MCPj kinematics. Twelve healthy horses were equipped with portable inertial sensors on the distal limb. The MCPj extension and the MCPj range of motion were assessed during walking and trotting without the orthotic (S0) and with the orthotic using two different support settings (S1 and S4). Data were evaluated for normality and homoscedasticity. A Student t-test was used to compare the MCPj angle pattern of the two forelimbs of each horse at the baseline. Data were analysed using one-way ANOVA to compare the mean values across conditions, followed by paired t-tests for post-hoc comparison (significance set at p < 0.05). The results showed significant reductions in both the MCPj extension and the MCPj range of motion, with the greatest restriction occurring at the highest support setting. These results suggest that the semirigid orthotic limits the MCPj movement in the sagittal plane and consequently the load on the suspensory ligament and flexor tendons. Therefore, this orthotic device is an effective tool during rehabilitation for forelimb tendon and ligament injuries.

Tarsocrural osteochondrosis (OCD) is a developmental orthopedic disease commonly affecting young Standardbreds, with different fragment localization and size. Clinically, it is characterized by variable synovial effusion in the absence of lameness, whose determinants are ill-defined. We hypothesized that localization and physical characteristics of the osteochondral fragments like dimensions, multifragmentation, and instability influence joint effusion and correlate with synovial markers of cartilage degradation and inflammation. Clinical data, synovial fluid and intact osteochondral fragments were collected from 79 Standardbred horses, aged between 12 and 18 months, operated for tarsocrural OCD. The severity of tarsocrural joint effusion was assessed semi-quantitatively. The osteochondral fragment site was defined radiographically at the distal intermediate ridge of the tibia (DIRT), medial malleolus (MM) of the tibia, and/or lateral trochlear ridge (LTR) of the talus. Size, stability, and arthroscopic appearance (unique or multi-fragmented aspect) of the fragments were determined intra-operatively. Synovial concentrations of C-terminal cross-linked telopeptides of type II collagen (CTX-II), leukotriene B4 (LTB4), and prostaglandin E2 (PGE2) were quantified. Tarsocrural synovial effusion was significantly affected by localization and stability of the fragments, with MM-located and unstable fragments being associated with highest joint effusion. Concentrations of CTX-II, LTB4, and PGE2 positively correlated with the severity of synovial effusion. This study underlines characteristics of the osteochondral fragments determining higher synovial effusion in OCD-affected tarsocrural joints and suggests both inflammation and extra-cellular matrix degradation are active processes in OCD pathology.

An 18‐month‐old Standardbred colt, referred for hock joint arthroscopy, presented a severe left forelimb lameness immediately after recovery from general anaesthesia. The horse was found in the recovery box with a ‘dropped elbow’, and it was dragging the leg. Radiographic examination of the shoulder showed a displaced avulsion fracture of the supraglenoid tubercle of the scapula. A human distal femoral locking plate was customised using measurements taken from a computed tomography scan of a 2‐year‐old horse specimen. An internal fixation of the fracture was performed using the designed distal femoral locking plate. Rehabilitation techniques were passive manipulations and neuromuscular electrical stimulation. Six months post‐operatively, the horse was sound and had made a complete functional recovery. The distal femoral locking plate fitted well to the supraglenoid tubercle and scapula in the operated horse, leading to a stable fixation. The recovery time was shortened using internal fixation, which facilitated a faster return to mobility.

Summary: Internal bleeding and mucosal bleeding in hollow organs are uncommon conditions in equine medicine and endoscopy. Most of the time, they respond to treatment of the underlying primary condition. However, there are cases in which a rapid and effective control of blood loss is required and the animal is not suited for surgery or general anaesthesia. We report two cases referred to our Veterinary Teaching Hospital with signs of urinary disease and bladder haemorrhage identified by cystoscopy which were successfully managed with topical application of a haemostatic carboxymethyl‐starch powder. The product was applied directly on the bleeding mucosa after bladder emptying either under endoscopic guidance or blindly, through a urinary catheter. The application of the haemostatic powder appears to be easy to perform, safe and helpful in controlling mucosal bleeding in hollow organs in a short time, with no adverse reactions noticed. This approach should be considered in cases where mucosal bleeding can be identified by endoscopy and a prompt control of blood loss is required, also in the field.

Obtaining a healthy wound environment that is conductive to healing in horses can be challenging. Negative-pressure wound therapy (NPWT) has been employed in humans to enhance wound healing for decades. The existing evidence for the effectiveness of NPWT remains uncertain in equine medicine. The aim of this review is to investigate NPWT applications and benefits in horses. A scoping review was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines for scoping reviews on three databases (PubMed, Web of Science-Thompson Reuters, and Wiley Online Library). Twenty-four manuscripts were considered. After removing duplicates, 17 papers underwent abstract screening. Of these, 16 + 1 (cited by others) were evaluated for eligibility according to PICOs, including no case reports/retrospective studies, four original articles, and three reviews. Fifteen manuscripts met the inclusion criteria. The focus of the articles was wound management; they included three reports of wounds communicating with synovial structures. Traumatic wounds and surgical-site infections are indications for NPWT. NPWT presents several advantages and few complications making it an attractive alternative to conventional wound management. However, randomized controlled trials should be performed to quantify the benefits and establish precise protocols in horses.

The interest in the properties of animal soft tissues is often related to the desire to find an animal model to replace human counterparts due to the unsteady availability of human tissues for experimental purposes. Once the most appropriate animal model is identified, it is possible to carry out ex-vivo and in-vivo studies for the repair of ligamentous tissues and performance testing of replacement and support healing devices. This work aims to present a systematic review of the mechanical properties of ligaments reported in the scientific literature by considering different anatomical regions in humans and several animal species. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. Moreover, considering the lack of a standard protocol for preconditioning of tissues, this aspect is also addressed. Ninety-six studies were selected for the systematic review and analysed. The mechanical properties of different animal species are reported and summarised in tables. Only results from studies reporting the strain rate parameter were considered for comparison with human ligaments, as they were deemed more reliable. Elastic modulus, ultimate tensile stress, and ultimate strain properties are graphically reported identifying the range of values for each animal species and to facilitate comparison between values reported in the scientific literature in animal and human ligaments. Useful similarities between the mechanical properties of swine, cow, and rat and human ligaments have been found.

Internal bleeding and mucosal bleeding in hollow organs are uncommon conditions in equine medicine and endoscopy. Most of the times, they respond to treatment of the underlying primary condition. However, there are cases in which a rapid and effective control of blood loss is required and the animal is not suited for surgery or general anaesthesia. We report two cases referred to our Veterinary Teaching Hospital with signs of urinary disease and bladder haemorrhage identified by cystoscopy which were successfully managed with topical application of a haemostatic carboxymethyl-starch powder. The product was applied directly on the bleeding mucosa after bladder emptying either under endoscopic guidance or blindly, through a urinary catheter. The application of the haemostatic powder appears to be easy to perform, safe, and helpful in controlling mucosal bleeding in hollow organs in the short time, with no adverse reactions noticed. This approach should be considered in cases where mucosal bleeding can be identified by endoscopy and a prompt control of blood loss is required, also in the field.