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Thirty stock type geldings (15 ± 3 y; 556 ± 63 kg BW) were used in a randomized complete design for a 28-d trial to evaluate the influence of cannabidiol (CBD) oil supplementation on health of mature horses by conducting a blood chemistry panel and evaluating the presence of banned substances. Horses were stratified by BW and age, and randomly assigned to 1 of 3 dietary treatments formulated with canola oil to provide.50 mg CBD/kg BW (TRT1; n = 10), 0.75 mg CBD/kg BW (TRT2; n = 10), or 0.00 mg CBD/kg BW (canola oil; CON; n = 10) only as determined by manufacturer (Arrowhead Labs). Treatments were individually fed and top-dressed onto a commercially available concentrate twice daily at 12 h intervals using attachable feed bags. Diets were formulated to meet or slightly exceed nutritional requirements for mature horses at maintenance. Between meals, horses were maintained in adjacent dry lots and received coastal bermudagrass hay ad libitum. Body weight was obtained, and body condition scores (BCS) were assigned every4 d. On d 0 and 28, blood was collected via jugular venipuncture and serum was harvested to perform a blood chemistry panel and drugs of abuse screening at the Texas Veterinary Medical Diagnostic Laboratory (TVMDL; College Station, TX). Data were analyzed using PROC MIXED of SAS (v9.4), and the model included treatment, time, and the treatment × time interaction for BW and BCS. Blood chemistry variables on d 0 were used as a covariate and the main effect tested was treatment. Linear and quadratic orthogonal polynomial contrasts were used to partition sum of squares. Analysis of supplement samples revealed supplemented products contained lower CBD concentrations then indicated from initial testing. Therefore, horses in TRT1 and TRT2 received an average of 0.13 mg CBD/kg and 0.12 mg CBD/kg BW, respectively. Dietary treatments did not affect concentrate intake, BW, or BCS. Supplementation of CBD did not result in the presence of any banned substances in serum, including CBD, 7-carboxycannabidiol, 7-Nor-7-carboxycannabidiol, and tetrahydrocannabinol (THC). Following 28 d of supplementation, gamma-glutamyl transferase (GGT) responded quadratically (P = 0.06) to treatment, with a peak in GGT in horses receiving TRT2. Serum creatinine concentration tended (P = 0.06) to decrease with increasing inclusion of CBD in the diet. In contrast, the main effect of treatment on Ca concentrations was linear (P = 0.01) and characterized by decreased Ca values for TRT1 compared with TRT2 and CON. Canola based CBD oil was well-accepted by mature horses, banned substances were not detectible in blood, and blood chemistry parameters were not adversely affected as a result of supplementation; however, more information is needed to improve stability of CBD used in dietary products.

OBJECTIVE To determine the effectiveness of a digital interactive multimedia tutorial (DIMT) for preparing veterinary students to perform ultrasonography in horses. SAMPLE 42 third-year veterinary students. PROCEDURES Students were randomly assigned to 3 instructional methods: independent study (ie, 45 minutes to read a highlighted textbook chapter), lecture (ie, 45-minute lecture by a faculty member), or digital interactive multimedia tutorial (DIMT; ie, 45-minute narrated, interactive module). Written and practical tests were administered after each instruction session. For the practical test, each student was required to obtain a series of ultrasound images of a live horse, and images were later scored for quality by an individual unaware of the instructional method used. RESULTS Higher-quality ultrasound images were obtained by veterinary students who had reviewed the DIMT rather than the analogous information in textbook chapters. No difference in scores was identified between students in the lecture group and those in the DIMT group. Students’ perceptions suggested that practical instruction facilitated by clinicians was a key component of learning how to perform ultrasonography in horses. CONCLUSIONS AND CLINICAL RELEVANCE Results supported the use of DIMTs in preparing veterinary students to perform ultrasonography in horses.

Dietary intervention may be a valuable strategy to optimize the intra-articular environment in young horses to prolong their performance career. To test the hypothesis that dietary supplementation of a Saccharomyces cerevisiae fermentation product would reduce markers of joint inflammation and increase markers of cartilage metabolism following a single inflammatory insult, Quarter Horse yearlings (mean ± SD; 9 ± 1.0 mo) were balanced by age, sex, body weight (BW), and farm of origin and randomly assigned to the following treatment groups: 1.25% BW/d (dry matter basis) custom-formulated concentrate only (CON; n = 9) or concentrate top-dressed with 21 g/d S. cerevisiae fermentation product (SCFP; n = 10) for 98 d. Horses had ad libitum access to Coastal bermudagrass hay. On day 84, one randomly selected radial carpal joint from each horse was injected with 0.5 ng lipopolysaccharide (LPS) solution. The remaining carpal joint was injected with sterile lactated Ringer’s solution as a contralateral control. Synovial fluid obtained before supplementation (day 0) and on day 84 at preinjection hour 0 and 6, 12, 24, 168, and 336 h postinjection was analyzed for prostaglandin E2 (PGE2), carboxypropeptide of type II collagen (CPII), and collagenase cleavage neopeptide (C2C) by commercial assays. Rectal temperature, heart rate, respiration rate, carpal surface temperature, and carpal circumference were recorded prior to each sample collection and for 24 h postinjection. Data were analyzed using linear models with repeated measures. From day 0 to 84, synovial C2C declined (P ≤ 0.01) and the CPII:C2C ratio increased (P ≤ 0.01) in all horses with no effect of diet. In response to intra-articular LPS, synovial PGE2 increased by hour 6 (P ≤ 0.01) and returned to baseline by hour 336; CPII increased by hour 12, remained elevated through hour 168 (P ≤ 0.01), and returned to baseline by hour 336; and C2C increased by hour 6 (P ≤ 0.01) but did not return to baseline through hour 336 (P ≤ 0.01). Post-intra-articular injection, PGE2 levels were lower in SCFP than CON horses (P = 0.01) regardless of injection type. Synovial CPII and the CPII:C2C ratio demonstrated stability during the LPS challenge in SCFP compared with CON horses (P ≤ 0.01). Clinical parameters were not influenced by diet but increased in response to repeated arthrocentesis (P ≤ 0.01). Dietary SCFP may favorably modulate intra-articular inflammation following an acute stressor and influence cartilage turnover in young horses.

Off-label bisphosphonate use in juvenile horses is widespread despite little scientific understanding of biological and welfare impacts on skeletally immature, exercising horses. Therefore, the objective was to determine the effects of clodronate disodium on growth parameters of young horses. Thirty-two yearling Quarter horses (335 ± 4 kg, 500 ± 13 d of age) were stratified by age, BW, sex, and initial bone density by aluminum equivalence into four treatment groups for a 168-d trial. The experimental period was divided into two phases mimicking common management practices in horses undergoing sales preparation (Phase I: d 0 to 83) and early performance training (Phase II: d 84 to 168). Horses were housed in individual stalls (3.6 m × 7.2 m). Diets were formulated to meet nutrient requirements including concentrate offered every 12 h and ad libitum access to coastal bermudagrass (Cynodon dactylon) hay and water. Treatments consisted of control (CON; n = 8), single-dose (1X; n = 8), two-dose (2X; n = 8), and four-dose groups (4X; n = 8). All horses received iso-volumetric intramuscular injections of either 1.8 mg/kg BW clodronate disodium (OSPHOSÒ) or saline (placebo) on d 0, 42, 84, and 126. Physical measurements including BW, wither height (WH), hip height (HH), body length (BL), and heart girth (HG) circumference were recorded every 42 d, beginning on d 0. Data were analyzed using PROC MIXED procedure of SAS. There were no treatment differences (P ≥ 0.62) or treatment ′ time interactions (P ≥ 0.25) for BW, WH, HH, BL, and HG, but all measurements increased over time (P ≤ 0.01). These results indicate that clodronate does not impact physical growth parameters in juvenile horses undergoing forced exercise. Further work is ongoing to determine tissue-specific effects of clodronate on bone growth and development in yearling Quarter horses.

BACKGROUND Outcomes following proximal interphalangeal joint (PIPJ) arthrodesis by a variety of surgical methods are available. Reports detailing clinical outcomes following PIPJ arthrodesis utilising the proximal interphalangeal joint locking compression plate (PIP-LCP) and abaxial transarticular lag screws technique are limited. OBJECTIVES To report survival, radiographic and clinical outcomes following PIPJ arthrodesis with PIP-LCP and abaxial transarticular lag screw fixation. STUDY DESIGN Retrospective case series. METHODS Medical records of all horses undergoing pastern arthrodesis from 2009 to 2018 were reviewed. Arthrodeses performed using a 3-hole, 4.5 mm narrow LCP, specifically designed for the proximal interphalangeal joint, were included. Patient details, presentation, radiographic findings, intraoperative and post-operative data, and complications were documented. Short- and long-term follow-up was available for 23 horses. RESULTS Thirty PIPJ arthrodeses were performed in 29 horses meeting the criteria for inclusion. Twenty-eight horses (97%, 95% CI 83-100) survived to discharge. Twenty-three horses (79%, 95% CI 60%-92%) had successful outcomes including 12 of the 15 forelimb cases and 11 of the 13 hindlimb cases with available follow-up. Fifteen of 19 performance horses returned to athletic activity. Soundness in performance horses was recognised at less than 3 months in one case, 3 to 6 months in six cases, 6 to 12 months in five cases, and greater than 12 months in six cases. Complications included three implant infections, support limb laminitis (two horses), and fragmentation of the extensor process of the distal phalanx (one horse). MAIN LIMITATIONS A retrospectively reviewed, small study population with a variety of breeds and disciplines. CONCLUSIONS The PIP-LCP construct provides a very good prognosis for performance and an excellent prognosis for pasture soundness.

To determine the effectiveness of a digital interactive multimedia tutorial (DIMT) for preparing veterinary students to perform ultrasonography in horses.42 third-year veterinary students.Students were randomly assigned to 3 instructional methods: independent study (ie, 45 minutes to read a highlighted textbook chapter), lecture (ie, 45-minute lecture by a faculty member), or digital interactive multimedia tutorial (DIMT; ie, 45-minute narrated, interactive module). Written and practical tests were administered after each instruction session. For the practical test, each student was required to obtain a series of ultrasound images of a live horse, and images were later scored for quality by an individual unaware of the instructional method used.Higher-quality ultrasound images were obtained by veterinary students who had reviewed the DIMT rather than the analogous information in textbook chapters. No difference in scores was identified between students in the lecture group and those in the DIMT group. Students' perceptions suggested that practical instruction facilitated by clinicians was a key component of learning how to perform ultrasonography in horses.Results supported the use of DIMTs in preparing veterinary students to perform ultrasonography in horses.

While beneficial in rehabilitation, aquatic exercise effects on bone metabolism in young, healthy horses has not been investigated. Therefore, thirty Quarter Horse yearlings were stratified by age, body weight (BW), and sex and randomly assigned to one of three treatments during a 140-d trial to evaluate aquatic vs. dry exercise on bone metabolism in young horses transitioning to an advanced workload. Treatment groups included non-exercise control (CON; n = 10), dry treadmill exercise (DRY; n = 10), or aquatic treadmill exercise (H2O; n = 10; water: 60% wither height, WH). Animals were housed in individual stalls (3.6 m×3.6 m) from 0600 to 1800, allowed turnout (74 m×70 m) from 1800 to 0600, and fed to meet or exceed requirements. During Phase I, DRY and H2O walked on treadmills 30 min/d, 5 d/wk from d 0–112. Phase II transitioned to an advanced workload 5 d/wk for 28 d (Table 1). Every 14 d, WH, hip height (HH), and BW were recorded. Every 28 d following exercise, serum samples were collected for osteocalcin (OC) and C-telopeptide crosslaps of type I collagen (CTX-1) analysis. Left third metacarpal radiographs on d 0, 112, and 140 were analyzed for radiographic bone aluminum equivalence (RBAE). Data were analyzed using PROC MIXED of SAS. Baseline treatment differences in biomarkers were accounted for using a covariate. There were treatment ′ day interactions (P < 0.01) where OC and CTX-1 remained consistent in both exercise groups while inconsistently increasing in CON. There were no treatment differences (P > 0.30) in RBAE, BW, or HH, but all increased over time (P < 0.01). There was a tendency toward a treatment × day interaction for WH (P = 0.07), characterized by a difference in response by CON during the first 28 d. This study indicates that early forced exercise supports consistent bone metabolism necessary for uniform growth and bone development, while lack of forced exercise results in incongruent bone turnover.

While beneficial in rehabilitation, aquatic exercise effects on cartilage and bone metabolism in young, healthy horses has not been well described. Therefore, 30 Quarter Horse yearlings (343 ± 28 kg; 496 ± 12 d of age) were stratified by age, body weight (BW), and sex and randomly assigned to 1 of 3 treatments for 140-d to evaluate effects of aquatic, dry, or no exercise on bone and cartilage metabolism in young horses transitioning to an advanced workload. Treatments included nonexercise control (CON; n = 10), dry treadmill (DRY; n = 10), or aquatic treadmill exercise (H2O; n = 10; water: 60% wither height, WH). Horses were housed individually (3.6 × 3.6 m) from 0600 to 1800 hours, allowed turnout (74 × 70 m) from 1800 to 0600 hours, and fed to meet or exceed requirements. During phase I (days 0 to 112), DRY and H2O walked on treadmills 30 min/d, 5 d/wk. Phase II (days 113 to 140) transitioned to an advanced workload 5 d/wk. Every 14-d, WH, hip height (HH), and BW were recorded. Left third metacarpal radiographs on days 0, 112, and 140 were analyzed for radiographic bone aluminum equivalence (RBAE). Every 28-d, serum samples were analyzed for osteocalcin and C-telopeptide crosslaps of type I collagen (CTX-1), and synovial fluid samples were analyzed for prostaglandin E2, collagenase cleavage neopeptide (C2C), collagenase of type I and type II collagen, and carboxypeptide of type II collagen using ELISAs. All data were analyzed using PROC MIXED of SAS, including random effect of horse within treatment, and repeated effect of day. Baseline treatment differences were accounted for using a covariate. There were treatment × day interactions (P < 0.01) where OC and CTX-1 remained consistent in both exercise groups while inconsistently increasing in CON. There were no treatment differences (P > 0.30) in RBAE, BW, or HH, but all increased over time (P < 0.01). There were no treatment × day interactions of synovial inflammation or markers of cartilage metabolism; however, there was an effect of day for each marker (P

Objective To determine the influence of epidural detomidine and morphine on serum corticosteroid concentrations and pain-related behavioral responses in mares during and after ovariectomy via colpotomy. Study design Blinded prospective study. Animals Nine university-owned mares. Methods Five of 9 horses received caudal epidural detomidine hydrochloride (0.01 mg/kg) and morphine sulfate (0.1 mg/kg) prior to surgery. All horses received local anesthetic around the ovarian pedicle, 0.02 mg/kg butorphanol IV at the start of the procedure and after first ovary removal, were sedated as required throughout the procedure, and were monitored for leg lifting, grunting, and abdominal tensing. Horses were monitored hourly for pain postoperatively. Heart rate was recorded every 4 hours, and photographs were taken to assess pain according to the horse grimace scale (HGS). Control group horses (n = 4) were treated with butorphanol (0.02 mg/kg IV) every 4 hours for 24 hours postoperatively. All horses received oral phenylbutazone 18 hours postoperatively. Serum cortisol was measured prior to the procedure, after first and second ovary removal, and 8 and 24 hours postoperatively. Results No differences were detected between horses receiving caudal epidural detomidine and morphine and those that received systemic opioids. A decrease in HGS score occurred after phenylbutazone administration. Conclusion Administration of caudal epidural detomidine and morphine resulted in similar pain-related behavior and corticosteroid concentrations as did administration of systemic butorphanol every 4 hours for 24 hours postoperatively. Clinical significance Caudal epidural detomidine and morphine may mitigate the requirement for frequent systemic opioid administration after a potentially painful procedure.

Aquatic treadmills improve range of motion and increase muscular strength in mature horses; however, effects of buoyancy on inflammation and cartilage metabolism in young horses are not well investigated. Therefore, thirty Quarter Horse yearlings of similar breeding were stratified by age, BW, and sex and randomly assigned to one of three treatment groups during a 140-d trial to evaluate the influence of aquatic vs. dry exercise on joint inflammation and cartilage metabolism in young horses transitioning to an advanced workload. Treatment groups included non-exercise control (CON; n = 10), dry treadmill exercise (DRY; n = 10), or aquatic treadmill exercise (H2O; n = 10; water at 60% wither height). Animals were housed in individual stalls and allowed turnout for a minimum of 10 h/d. During Phase I, DRY and H2O walked on treadmills 30 min/d, 5 d/wk from d 0 to d 112. Phase II represented transition to an advanced workload 5d/wk for 28 d (Table 1). Every 28 d following exercise, synovial fluid samples were collected and analyzed for prostaglandin E2 (PGE2), collagenase cleavage neopeptide (C2C), collagenase of type I and type II collagen (C1,2C), and carboxypeptide of type II collagen (CPII) using commercial ELISA kits. All data were analyzed using PROC MIXED of SAS, including random effect of horse within treatment, and repeated effect of day. Baseline treatment differences were accounted for using a covariate structure. There were no treatment ′ day interactions of synovial inflammation or markers of cartilage metabolism; however, there was an effect of day for each selected marker (P < 0.03). Changes in biomarkers of cartilage turnover in horses exercised at the walk, whether dry or aquatic, could not be distinguished from horses with access to turnout alone. This indicates that there are no negative effects of buoyancy on cartilage metabolism in yearlings transitioned from aquatic exercise to 28-d advanced workload.

OBJECTIVE To describe the signalment, clinical features, and outcome for male horses with urethral rents following perineal urethrotomy (PU) or corpus spongiotomy (CS). DESIGN Retrospective case series. ANIMALS 33 horses. PROCEDURES Medical records of male horses examined because of hematuria or hemospermia caused by urethral rents that underwent PU or CS at a referral hospital between 1989 and 2013 were reviewed. Data regarding signalment, clinical features, urethroscopic findings, surgical treatment, and outcome were recorded. Long-term follow-up information was obtained by telephone interviews. RESULTS Age of the study population ranged from 3 to 18 years. Nineteen geldings and 1 stallion were examined because of hematuria, of which 13 and 7 underwent PU and CS, respectively, at a mean of 56 days after onset of clinical signs. Thirteen stallions were examined because of hemospermia, of which 7 and 6 underwent PU and CS, respectively, at a mean of 193 days after onset of clinical signs. Hematuria resolved following 1 surgical procedure in all 17 horses for which long-term information was available. Of the 12 stallions for which long-term information was available, 7 had resolution of hemospermia after 1 PU or CS and 5 developed recurrent hemospermia that required additional PUs or CSs (n = 3) or primary closure of the urethral rent (2). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that PU and CS were reliable treatments for resolution of hematuria in male horses with urethral rents; stallions with urethral rents may require multiple PUs or CSs or primary closure of the rent for resolution of hemospermia.

Despite differences in etiology and diagnostics, the mainstay of therapy in the foal is similar to the adult: local lavage and/or debridement and local antimicrobial therapy. When musculoskeletal infection is concurrent with neonatal sepsis, the prognosis for survival is fair. When musculoskeletal infection is the primary problem, the prognosis is fair to good for survival of synovial, bony, and physeal infections with appropriate and aggressive local therapy. Recent literature may indicate that prognosis for survival and potential athleticism in foals that are treated expediently with local therapies and are without comorbidities may be more favorable than has been previously indicated.

Many long bone fractures that are not considered repairable in the adult horse are repairable in the foal. This is largely because of reduced patient size and more rapid healing in the foal. When there is no articular communication, the long-term prognosis for athletic function can be very good. Emergency care and transport of the foal with a long bone fracture is different than the adult.

Background Isolation of multiple bacterial species is common in foals with Rhodococcus equi pneumonia. Hypothesis There is no association between isolation of other microorganisms and outcome. Animals 155 foals with pneumonia caused by R. equi. Methods Case records of foals diagnosed with R. equi pneumonia based on culture of the respiratory tract were reviewed at 2 referral hospitals (University of Florida [UF] and Texas A&M University [TAMU]). Results R. equi was cultured from a tracheobronchial aspirate (TBA) in 115 foals and from lung tissue in 38 foals. Survival was significantly higher at UF (71%; 70/99) than at TAMU (50%; 28/56). R. equi was significantly more likely to grow in pure cultures from samples obtained from foals at UF (55%; 54/99) than from foals at TAMU (23%; 13/56). Microorganisms cultured with R. equi included Gram-positive bacteria in 40, Gram-negative bacteria in 41, and fungi in 23 foals. The most common bacteria isolated were beta-hemolytic streptococci (n = 26) and Escherichia coli (n = 18). Mixed infections were significantly more likely to be encountered in TBA than in lung tissue. Only foals from which R. equi was cultured from a TBA were included in the analysis for association between mixed infection and outcome. After adjusting for the effect of hospital using multivariate logistic regression, mixed culture, mixed bacterial culture, Gram-positive bacteria, beta-hemolytic streptococci, Gram-negative bacteria, enteric Gram-negative bacteria, nonenteric Gram-negative bacteria, and fungi were not significantly associated with outcome. Conclusions and Clinical Importance Isolation of multiple bacteria or fungi from a TBA along with R. equi does not negatively impact prognosis.