Renin-Angiotensin-Aldosterone System Profiling in Horses Before and After Exercise.

Background: The impact of exercise on the classical and alternative renin-angiotensin-aldosterone system (RAAS) pathways has not been studied in horses.

Hypothesis: We hypothesized that exercise would activate both RAAS pathways and that endurance exercise would cause more activation of the classical pathway compared to short-duration, high-intensity exercise in horses.

Animals: Twenty-five horses (21 client-owned and 4 research) were included in 4 exercise groups (10 Arabians, 50-mile ride [A-E]; 4 thoroughbreds, 1-mile treadmill exercise [TB-TM]; 5 thoroughbreds, 1-1/16th-mile race [TB-R]; and 6 quarter horses 330-500-yard race [QH-R]).

Bupivacaine and liposomal bupivacaine do not produce prolonged perineural anesthesia in a lameness model and are detectable beyond clinical effect in conditioned Thoroughbreds.

Objective: To determine (1) the dose of liposomal bupivacaine (LB) to eliminate grade 2 of 5 lameness, the (2) duration of analgesia of LB versus bupivacaine hydrochloride (BH), and (3) LB pharmacokinetics versus BH.

Methods: A reversible lameness model was validated in conditioned Thoroughbred horses (n = 12), aged 3 to 10 years. A dose-response trial compared subjective and objective lameness following abaxial sesamoid block with 25 mg BH/nerve or 30, 60, or 133 mg LB/nerve (n = 3/group).

Pharmacokinetics and tolerability of single-dose enteral cannabidiol and cannabidiolic acid rich hemp in horses ().

The pharmacokinetics and tolerability of cannabinoids and their metabolites were determined in eight horses after enteral administration of a commercial CBD/CBDA-rich hemp oil product. Each horse was administered 2 mg/kg or 8 mg/kg CBD/CBDA or no treatment in a randomized cross-over design. Serial serum samples collected over 48 h were analyzed by high performance liquid chromatography with tandem mass spectrometry.

Equine Platelet-Rich Plasma.

Platelet-rich plasma (PRP) is an orthobiologic therapy composed of platelets, leukocytes, red blood cells, and plasma proteins. PRP has been used for 20 years, but progress determining efficacy has been slow. The definitions and classification of PRP are reviewed, and the use of PRP for tendon, ligament, and joint disease is discussed with a focus on findings of basic science and clinical studies, platelet activation, concurrent administration of nonsteroidal anti-inflammatory drugs, and treatment complications.

Antimicrobial prophylaxis is not indicated for horses undergoing general anaesthesia for elective orthopaedic MRI.

Background: Post-anaesthetic fever is a known complication of general anaesthesia, however, its incidence in horses undergoing elective magnetic resonance imaging (MRI) is unknown.

Objective: To determine the incidence of post-anaesthetic fever in horses undergoing elective orthopaedic MRI and determine whether prophylactic antimicrobial therapy would be associated with a reduction in the incidence of post-anaesthetic fever. We hypothesised that prophylactic antimicrobials would be associated with a reduction in the incidence of post-anaesthetic fever.

Three-dimensional models of the equine larynx can be used to perform traditional measures of arytenoid abduction and permit the positioning of modeled implants to demonstrate the anatomic feasibility of placing a rigid implant across the cricoarytenoid joint.

Objective: To develop 3D models of larynges to compare arytenoid abduction measurements between specimens and models, and to investigate the anatomic feasibility of placing an implant across the cricoarytenoid joint (CAJ) with or without arthrotomy.

Samples: Cadaveric equine larynges (n = 9).

Procedures: Equine larynges underwent sequential CT scans in a neutral position and with 2 arytenoid treatments: bilateral arytenoid abduction (ABD) and bilateral arytenoid abduction after left cricoarytenoid joint arthrotomy (ARTH).

Pharmacokinetics of aminocaproic acid in thoroughbred horses.

The antifibrinolytic agent aminocaproic acid (ACA) is occasionally used prior to episodes of intense training in racehorses suffering from exercise-induced pulmonary hemorrhage. Although a previous study indicated that the drug is cleared rapidly in horses, some racetrack practitioners claim that recent adverse analytical findings for ACA in postrace samples were from ACA administrations 5-7 days before the race. The purpose of this study was to re-examine the pharmacokinetics of ACA in horses to address this apparent conundrum.

Kinematics of the equine distal sesamoid (navicular) bone of the thoracic limb.

Objective: To quantify the translation and angular rotation of the distal sesamoid bone (DSB) using computed tomography (CT) and medical modeling software.

Sample: 30 thoracic limbs from equine cadavers.

Procedures: Partial (n = 12), full (8), and matched full and subsequently transected (10) thoracic limbs were collected.

Novel Methods to Mobilize, Isolate, and Expand Mesenchymal Stem Cells.

Numerous studies demonstrate the essential role of mesenchymal stem cells (MSCs) in the treatment of metabolic and inflammatory diseases, as these cells are known to modulate humoral and cellular immune responses. In this manuscript, we efficiently present two novel approaches to obtain MSCs from equine or human sources. In our first approach, we used electro-acupuncture as previously described by our group to mobilize MSCs into the peripheral blood of horses.

Three-dimensional printed guides for screw placement in equine navicular bones.

Objective: To determine the influence of a custom 3D-printed guide for placement of cortical bone screws in the equine navicular bone.

Study Design: Ex vivo study.

Sample Population: Eight pairs of normal adult equine forelimbs.

Endoscopic Laser Ablation of a Midline Cyst of the Colliculus Seminalis as a Treatment for Anejaculation in a Stallion.

An 18-year-old Appaloosa stallion presented with a history of ejaculatory dysfunction, which had recently progressed to an inability to ejaculate (anejaculation). Transrectal ultrasound evaluation revealed the presence of a prominent midline cyst of the colliculus seminalis, which was compressing the most terminal parts of the deferent ducts. Both ducts were enlarged and filled with hyperechoic content.

The effect of four different freezing conditions and time in frozen storage on the concentration of commonly measured growth factors and enzymes in equine platelet-rich plasma over six months.

Background: Platelet-rich plasma (PRP) is a therapeutic biologic that is used for treatment of musculoskeletal pathologies in equine athletes. Due to the expense of PRP kits, and the volumes obtained, freezing aliquots for future dosing is common. Aliquots of PRP are also commonly frozen for later analysis of growth factor concentrations in in vitro research.

Peripheral blood-derived mesenchymal stem cells demonstrate immunomodulatory potential for therapeutic use in horses.

Previously, we showed that mesenchymal stem cells (MSC) can be mobilized into peripheral blood using electroacupuncture (EA) at acupoints, LI-4, LI-11, GV-14, and GV-20. The purpose of this study was to determine whether EA-mobilized MSC could be harvested and expanded in vitro to be used as an autologous cell therapy in horses. Peripheral blood mononuclear cells (PBMC) isolated from young and aged lame horses (n = 29) showed a marked enrichment for MSCs.

Minimally Manipulated Bone Marrow Concentrate Compared with Microfracture Treatment of Full-Thickness Chondral Defects: A One-Year Study in an Equine Model.

Background: Microfracture is commonly performed for cartilage repair but usually results in fibrocartilage. Microfracture augmented by autologous bone marrow concentrate (BMC) was previously shown to yield structurally superior cartilage repairs in an equine model compared with microfracture alone. The current study was performed to test the hypothesis that autologous BMC without concomitant microfracture improves cartilage repair compared with microfracture alone.

Two-Year Evaluation of Osteochondral Repair with a Novel Biphasic Graft Saturated in Bone Marrow in an Equine Model.

Objective To evaluate a biphasic cartilage repair device (CRD) for feasibility of arthroscopic implantation, safety, biocompatibility, and efficacy for long-term repair of large osteochondral defects. Methods The CRD was press-fit into defects (10 mm diameter, 10 mm deep) created in the femoral trochlea of 12 horses. In the contralateral limb, 10 mm diameter full-thickness chondral defects were treated with microfracture (MFX).

Angular Limb Deformities: Growth Retardation.

Angular limb deformities are common in foals; however, the importance of the deformity and if treatment is required depend on the degree of deformity relative to normal conformation for stage of growth, the breed and discipline expectations, age, and response to conservative therapies. This article addresses the importance of the foal conformation examination to determine which foals need surgical intervention to correct an angular deformity and when. Techniques for surgical growth retardation include the transphyseal staple, screw and wire transphyseal bridge, and transphyseal screw.

Update on laryngeal disorders and treatment.

Laryngeal disorders are relatively common in the horse, and thorough diagnostic evaluation is essential to make an accurate definitive diagnosis and selection of appropriate treatment. The value of exercising endoscopy must not be overlooked, and the recent development of dynamic (overground) endoscopy is providing new insights into dynamic laryngeal lesions. The focus of this article will be on recently described disorders and treatments or modifications to existing treatments.

Considerations for the use of platelet-rich plasma in orthopedics.

The use of platelet-rich plasma (PRP) is expanding to numerous medical fields, including orthopedic surgery and sports medicine. The popularity of this new treatment option has prompted a rapid increase in research endeavors; however, the differences in application technique and the composition of PRP have made it difficult to compare results or make any firm conclusions regarding efficacy. The purpose of this article is twofold.

Optimization of leukocyte concentration in platelet-rich plasma for the treatment of tendinopathy.

Background: Numerous methods are available for platelet-rich plasma (PRP) generation, but evidence defining the optimum composition is lacking. We hypothesized that leukocyte-reduced PRP would result in lower inflammatory cytokine expression compared with concentrated-leukocyte PRP and that maintaining the platelet:white blood cell (WBC) ratio would compensate for the effect of increased WBC concentration.

Methods: Blood and flexor digitorum superficialis tendons were collected from young adult horses.

The role of growth factors in cartilage repair.

Background: Full-thickness chondral defects and early osteoarthritis continue to present major challenges for the patient and the orthopaedic surgeon as a result of the limited healing potential of articular cartilage. The use of bioactive growth factors is under consideration as a potential therapy to enhance healing of chondral injuries and modify the arthritic disease process.

Questions/purposes: We reviewed the role of growth factors in articular cartilage repair and identified specific growth factors and combinations of growth factors that have the capacity to improve cartilage regeneration.

Temporal growth factor release from platelet-rich plasma, trehalose lyophilized platelets, and bone marrow aspirate and their effect on tendon and ligament gene expression.

Platelet-rich plasma (PRP) has generated substantial interest for tendon and ligament regeneration because of the high concentrations of growth factors in platelet alpha-granules. This study compared the temporal release of growth factors from bone marrow aspirate (BMA), PRP, and lyophilized platelet product (PP), and measured their effects on tendon and ligament gene expression. Blood and BMA were collected and processed to yield PRP and plasma.