Investigation of equine testis contribution to vitamin D bioactivation.

Although vitamin D acts in various biological processes, it plays a critical role in the maintenance of bone health, and regulates calcium homeostasis. In humans and rodents, the main tissues involved in vitamin D metabolism are the liver and the kidneys, however it has been shown that the testis has strongly participated in its bioactivation. Indeed, in these different species, enzymes metabolizing vitamin D (CYP27A1, CYP27B1 and CYP2R1) have been demonstrated in this tissue. Moreover, men with hypogonadism have shown a decrease in circulating levels of vitamin D. In equine species, the castration of males is a regular practice to reduce the behavior of stallions deemed too aggressive. Castration is carried out at various ages: in foals during their growth or in adulthood once they have reached their optimum size. Although horses exhibit atypical vitamin D metabolism with low circulating levels of vitamin D, it was suggested that testis may contribute to its activation as has been described in rodents and humans; castration could therefore be likely to affect its metabolism. In this study, blood levels of bioactive form of vitamin D (1 α,25[OH] 2 vitamin D 3 ) were measured before and after castration at different ages: 1 wk, after puberty (2 yr) and at adulthood (6 yr). The gene expression of enzymes involved in vitamin D metabolism has been sought in the testis of different experimental groups. No change in bioactive vitamin D3 levels was observed after castration regardless of the age at the time of surgery. The exceptional status of equine species is confirmed with a low or a lack of testis contribution to vitamin D metabolism, regardless of testicular development. This is demonstrated by a low or a lack of signal from enzymes involved in vitamin D bioactivation. Therefore, horses constitute a unique model in comparative endocrinology.

Effects of sand, asphalt and 3-degree hind toe or heel elevation on horse kinematics.

BACKGROUND: Although the effects of both the surfaces and plantar angles on equine locomotion have been widely discussed, limited scientific data are available. METHODS: Our objectives were to determine the effects of two surfaces (asphalt and sand) and of 3-degree hind toe or heel elevation on horse kinematics in an experimental study. Six saddle horses were shod with a reference shoeing (REF), characterized by a fore aluminium (REF F) and hind steel racehorse (REF H) shoeing. Two dimensional kinematic videos compared horse's kinematic parameters when walking and trotting on asphalt and sand. On asphalt, REF was also compared with REF F and a modified REF H with additional 3-degree hind-toe or -heel wedges. RESULTS: On asphalt versus sand, horses had, at the trot, a shorter stride duration and forelimb maximal retraction, and at walk and trot, a greater fetlock, carpus, elbow and tarsus extension, a greater fore and hind limbs maximal protraction and a shorter hind limbs maximal retraction. Increasing the plantar angle decreased the tarsus and hind fetlock extension, in contrast to fore-limb, on asphalt during the stance phase. CONCLUSIONS: These findings could be useful to adapt rehabilitation programs related to fore and hind limb pathologies, at slow gaits.

Comparison of Serum Amyloid A Measurements in Equine Synovial Fluid With Routine Diagnostic Methods to Detect Synovial Infection in a Clinical Environment.

Synovial fluid analysis is utilized to diagnose septic synovitis. However, not all cases are clearly and rapidly discernible with the diagnostic tools available in the laboratory. Serum amyloid A (SAA), an acute phase protein, has been shown to be elevated in synovial fluid from inflamed synovial structures. The goal of this study is to describe the correlation between two diagnostic tests measuring equine SAA levels in septic and non-septic synovial structures and to understand the correlation between an elevated SAA result and synovial sepsis. Prospective estimation of sensitivity (Se) and specificity (Sp) of two tests, handheld and ELISA, measuring SAA in synovial fluid was completed in 62 horses presented with injured synovial structures. The comparison was made to a reference diagnosis based on white cell count, percentage of neutrophils, intracellular bacteria and bacterial culture on synovial fluid. Handheld test levels were classified as: 4 lines visible-SAA level negative; 3 lines visible-SAA level mild; 2 lines visible-SAA level moderate; and 1 line visible-SAA level severe and compared to the numerical value obtained with ELISA test. The ELISA SAA test had an area under the curve of 0.88 (0.78-0.98). An ELISA cut-off of 23.95 µg/mL maximized Se and Sp. This cutoff gave a Se of 0.93 (0.66-1.00) and Sp of 0.77 (0.63-0.88). The handheld test was highly correlated with the ELISA SAA test (Spearman rank correlation 0.96) and at a cutoff of moderate or higher for positive results gave identical Se and Sp. Se and Sp of synovial fluid SAA are very reliable when clinical signs of synovitis are present for >6 h. This test, in conjunction with traditional methods, can assist practitioners to rapidly diagnose and expedite appropriate intervention of synovial sepsis.

Effect of arthroscopic lavage and repeated intra-articular administrations of antibiotic in adult horses and foals with septic arthritis.

OBJECTIVE: To evaluate the effect of arthroscopic lavage and repeated intra-articular administration of antibiotic in adult horses and foals with septic arthritis. STUDY DESIGN: Retrospective clinical study. ANIMALS: Adult horses and foals with septic arthritis (n = 62). METHODS: Age, sex, cause of septic synovitis, joint involved, hospitalization time, and outcome were recorded. Arthroscopic lavage was performed at day 0 (D 0). Synovial fluid was collected every 48 hours prior to intra-articular administration of antibiotic, and until hospital discharge. Synovial nucleated cell count, total protein, and percentage of neutrophils were compared across time and between subjects with a favorable or unfavorable outcome. RESULTS: Synovial nucleated cell counts decreased progressively and were lower at all times compared to D 0. Percentages of neutrophils were lower than baseline at D 8 and 10, only. Total protein contents decreased progressively and were lower than baseline at D 2, 4, 6, 8, 10, and 14. When adult horses and foals with a favorable outcome were compared to those with an unfavorable outcome, the nucleated cell count was lower at D 10, 12, and 14 and the percentage of neutrophils was lower at D 4 only, but total protein content did not differ between groups at any time. CONCLUSION: Synovial nucleated cell counts and total protein concentrations decreased after arthroscopic lavage and repeated intra-articular administration of antibiotic in horses and foals with septic arthritis. Synovial nucleated cell count is limited as a monitoring tool during treatment of septic arthritis.

Techniques and Indications for Intraoperative Ultrasound in Horses.

OBJECTIVE: To describe our experience using intraoperative ultrasound for various conditions in horses. STUDY DESIGN: Retrospective case series. SAMPLE POPULATION: Horses (n=113). METHODS: Medical records including surgical reports at 2 equine hospitals (2007-2013) were reviewed to identify ultrasound-assisted surgeries. The diagnosis, reasons for using intraoperative ultrasound, the technique employed, and the surgical procedure performed (e.g., synovial endoscopy, cut-down, resection, dissection, curettage, and implant placement/removal) were recorded for each surgery. Intraoperative ultrasound was used to mark the optimal site for skin incision or to guide instrumentation within the tissues. The incision site was marked on the skin with staples. Depth soundings were taken on the ultrasound, using the caliper-measuring tool to facilitate dissection. For each surgery, the primary specialist surgeon (ACVS or ECVS) retrospectively recorded whether intraoperative ultrasound was helpful, unhelpful, or harmful. RESULTS: Intraoperative ultrasound was rated helpful in 105/113 (93%) of surgeries, unhelpful in 7/113 (6%), and harmful in 1/113 (1%) of surgeries. CONCLUSION: Intraoperative ultrasound can be a useful adjunct to surgical techniques for various conditions in horses.

Comparison of medial and lateral ultrasound-guided approaches for periarticular injection of the thoracolumbar intervertebral facet joints in horses.

OBJECTIVE: To compare ultrasound-guided lateral and medial approaches for periarticular injections of the thoracolumbar intervertebral facet joints (IFJ). STUDY DESIGN: Experimental cadaveric study. SAMPLE POPULATION: Adult equine cadavers (n=4). METHODS: IFJ (T12-T13 to L5-L6) were identified by ultrasound (transducer perpendicular to the spine axis) and insertion of a 13 cm, 18 g spinal needle monitored until bone contact using medial (right side) and lateral (left side) approaches. Number of needle insertions at each site, needle repositioning, and insertion depth were recorded. On bone contact 2 mL latex was injected. Intraarticular deposition, distance of latex from the closest articular margin, and presence of latex in the multifidus muscle were established by dissection. RESULTS: Of 96 attempts, only 1 site require reinsertion of the needle; however, 46% of the injections required needle repositioning. Mean ± SD insertion depth was 8.5 ± 1.1 cm. Most injections (86%) were intraarticular and 96% were at or within 0.5 cm of the closest articular margin. Needle insertion relative to the transducer (lateral, medial) had no effect on the distance from the latex to the closest articular margin and all injections were performed into the multifidus muscle. CONCLUSIONS: Ultrasound-guidance facilitated accurate periarticular injection of thoracolumbar IFJ irrespective of using a medial or lateral approach.