Plantar osteochondral fragments in young Standardbreds are associated with minimal joint inflammation at the time of surgical removal.

BACKGROUND: Plantar osteochondral fragments (POF) are common but their effect on joint health of young Standardbreds in race training is largely unknown. OBJECTIVES: Evaluate the inflammatory effects of POF in metatarsophalangeal joints of young Standardbreds as a step towards developing evidence-based recommendations for surgical removal. STUDY DESIGN: Cohort study. METHODS: Forty-nine Standardbred horses (age 11-33 months) presented for surgical removal of POF from 56 metatarsophalangeal joints. Synovial tissue collected at arthroscopy was subjected to histopathology. IL-1ß, TNF-α, and PGE-2 were measured in synovial fluid using ELISA. Digital arthroscopy images were scored for inflammation. Racing performance data were retrieved from a public database. RESULTS: Median time in race training prior to surgery was 8 weeks (IQR 4-12; range 0-40). There was minimal evidence of synovial inflammation as assessed by histopathology (median total score 2/20, IQR 0-2, range 0-5) or arthroscopy (median average total score 2.67/15, IQR 1.79-4, range 0-8.83). IL-1ß was not detected in any sample. TNF-α (median 0 pg/mL, IQR 0-0) and PGE-2 (median 56.6 pg/mL, IRQ 40.5-99.8) were measured at low levels. Weeks in training prior to surgery was associated with the number of starts in the season after surgery (incidence rate ratio 1.02, 95% CI 1.00, 1.04, P = .03). MAIN LIMITATIONS: Small sample size from a single breed with a relatively short training time prior to surgery. CONCLUSIONS: There was minimal evidence of synovial inflammation in the metatarsophalangeal joints in this population of young Standardbred horses with POF. It is possible that POF may result in a different inflammatory response than other fragments because they are generally well-embedded in situ. These findings suggest that, in Standardbreds, race training can commence several weeks prior to surgical removal of POF with minimal detrimental effects on joint health, although further investigation of long-term effects of POF on joint health is warranted.

INTRODUCTION/CONTEXTE: Les fragments plantaires ostéochondraux (POF) sont communs mais leur effet au niveau sur la santé articulaire chez les jeunes Standardbreds en entraînement de course demeure inconnu. OBJECTIFS: Évaluer les effets inflammatoires des POF des articulations métatarsophalangiennes chez les jeunes Standardbreds dans le but d'ajouter à l'évidence disponible concernant les recommandations pour leur retrait chirurgical. TYPE D'ÉTUDE: Étude de cohorte descriptive clinique. MÉTHODES: Quarante-neuf chevaux Standardbreds (âgés 11-33 mois) ont été présentés pour retrait chirurgical de POF en provenance de 56 articulations métatarsophalangiennes. Un échantillon de membrane synoviale recueilli au moment de l'arthroscopie a été soumis en histopathologie. IL-1ß, TNF-α, and PGE-2 ont été mesurés dans le liquide synovial par ELISA. Les images digitales d'arthroscopie ont été évaluées pour la présence d'inflammation. Les données de performance en course ont été retrouvées via une base de données publique. RÉSULTATS: Le temps médian de retour à l'entraînement suivant la procédure chirurgicale était de 8 semaines (IQR 4-12; étendu 0-40). Peu d'inflammation synoviale a été détectée en histopathologie (score médian total 2/20, IQR 0-2, étendu 0-5) ou arthroscopie (score médian total 2.67/15, IQR 1.79-4, étendu 0-8.83). IL-1ß a été détectée dans aucun échantillon. TNF-α (médiane 0 pg/mL, IQR 0-0) et PGE-2 (médiane 56.6 pg/mL, IQR 40.5-99.8) ont été détectés en faible quantité. Le nombre de semaines à l'entraînement avant la procédure chirurgicale était associé au nombre de départs pour la saison suivant la chirurgie (IRR 1.02, P = 0.03). LIMITES PRINCIPALES: Petite taille d'échantillon provenant d'une seule race de chevaux ayant une période d'entraînement relativement courte avant la procédure chirurgicale. CONCLUSIONS: Il y a peu d'évidence d'inflammation synoviale dans les articulations métatarsophalangiennes chez cette population de jeunes chevaux Standardbreds ayant des POF. Il est possible que les POF entraînent une réponse inflammatoire différente des autres fragments puisqu'ils sont généralement bien attachés dans l'articulation. Ces résultats suggèrent que chez les Standardbreds, l'entraînement de course puisse commencer plusieurs semaines avant le retrait chirurgical des POF en ayant des effets délétères minimaux pour la santé articulaire. Ceci dit, davantage de recherche est nécessaire pour établir les effets à long-terme de ces POF sur la santé articulaire.

The effect of repeated freezing and thawing on the suture pull-out strength in equine arytenoid and cricoid cartilages.

OBJECTIVE: To assess the effect of repeated freezing and thawing on the suture pull-out strength in arytenoid and cricoid cartilages subjected to the laryngoplasty (LP) procedure. STUDY DESIGN: Ex vivo experimental study. SAMPLE POPULATION: Ten grossly normal equine cadaveric larynges. METHODS: Bilateral LP constructs were created using a standard LP technique. One hemilarynx was randomly allocated to the single freeze and thaw group and the other allocated to the repeated freeze and thaw (3 complete cycles) group. The suture ends of each LP construct were attached to a load frame and subjected to monotonic loading until construct failure. Mean load (N) and displacement (mm) at LP construct failure were compared between groups. RESULTS: All LP constructs failed by suture pull through the arytenoid cartilage. The mean load at failure was similar between groups (118.9 ± 25.5 N in the single freeze and thaw group and 113.4 ± 20.5 N in the repeated freeze and thaw group, P = .62). The mean displacement at failure was similar between groups (54.4 ± 15.1 mm in the single freeze and thaw group and 54.4 ± 15.4 mm in the repeated freeze and thaw group, P = .99). CONCLUSION: Repeated freezing and thawing did not affect the suture pullout strength of the arytenoid and cricoid cartilages. CLINICAL SIGNIFICANCE: Laryngeal specimens that have been subjected to repeated freezing and thawing can be utilized in the experimental evaluation of LP procedures because there is no alteration of the suture pull-out strength of the relevant cartilages.

Performance of predictive models of survival in horses undergoing emergency exploratory laparotomy for colic.

OBJECTIVE: To evaluate previously published predictive survival models in a population of horses undergoing colic surgery in the midwestern United States. STUDY DESIGN: Retrospective cohort study; single referral hospital. ANIMALS: A total of 260 horses met the inclusion criteria. METHODS: Medical records of horses undergoing surgical treatment for colic were reviewed. Previously published models were applied to cohort data to predict outcome. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for prediction of short-term survival were calculated. RESULTS: Single-variable and multivariable models performed similarly for prediction of survival, with a mean 79% sensitivity (range: 44%-94%), 48% specificity (range: 22%-83%), 63% PPV (range: 56%-72%), 73% NPV (range: 60%-83%), and 64% accuracy (range: 59%-72%). Blood lactate ≤6 mmol/l and the colic severity score (CSS) were highly sensitive for prediction of survival; however, both had poor specificity. CONCLUSION: Single-variable and multivariable predictive models did not perform as well for prediction of survival in the study cohort compared to original reports, suggesting that population-specific factors contribute to patient survival. CLINICAL SIGNIFICANCE: Predictive models of survival developed in one population may be less reliable when used to predict outcome in horses undergoing colic surgery from an independent population. Additional model testing and refinement using data from multiple surgical centers could be considered to improve prediction of outcome for horses undergoing laparotomy for treatment of colic.

Kinetic Analysis in Horses With Deep Digital Flexor Tendinopathy Within the Digit Diagnosed by Magnetic Resonance Imaging.

Objectives: To determine the stance duration and ground reaction forces (GRF) of horses with deep digital flexor (DDF) tendinopathy at the level of the foot and compare the stance duration and GRF to those of clinically sound horses. Design: Prospective clinical study. Animals: Sixteen horses (seven horses with bilateral forelimb lameness, four horses with unilateral forelimb lameness, and five horses with no lameness). Procedures: Analyses of kinetic variables were performed on both forelimbs from sound horses and horses diagnosed with chronic DDF tendinopathy. Stance duration and longitudinal and vertical components of the GRF were determined for the limbs of clinically sound horses and limbs of horses with DDF tendinopathy. Separate Spearman correlation analyses were used to assess potential association within groups (combined left and right forelimbs of clinically sound horses, lamest limbs of horses with DDF tendinopathy, and contralateral limbs of horses with DDF tendinopathy) and with the set of kinetic variables. Analysis of variance on mean ranks of tied values was used to determine differences in kinetic variables between groups (PROC GLIMMIX) using the kinetic values of the clinically sound horses as the reference group. Results: There were a total of 11 lame horses. Seven horses had bilateral forelimb lameness and four had unilateral lameness. Of the 11 horses, there were 15 DDF tendinopathies. There were eight dorsal border DDF tendinopathies, five core DDF tendinopathies, and two sagittal/parasagittal splits DDF tendinopathies. The most lame limbs of horses with DDF tendinopathy had significantly smaller values for peak vertical force and time of peak braking force than did forelimbs of clinically sound horses. Also, the most lame limbs of horses with DDF tendinopathy had significantly larger values for the time of peak vertical force than did forelimbs of clinically sound horses. Conclusions and Clinical Relevance: Horses with chronic DDF tendinopathies develop certain alterations of GRF parameters. This information can be used in future studies to determine if particular kinetic variable changes in horses with DDF tendinopathies differ from those of horses with other pathologies within the foot and therefore could be diagnostic.

Evaluation of the airway mechanics of modified toggle laryngoplasty constructs using a vacuum chamber airflow model.

OBJECTIVE: To evaluate the airway mechanics of modified toggle LP constructs in an airflow chamber model and compare these to the airway mechanics of standard LP constructs. STUDY DESIGN: Ex-vivo experimental study. SAMPLE POPULATION: Fifty-one equine cadaveric larynges. METHODS: Bilateral LP constructs were performed using a modified toggle (n = 23) or a standard (n = 21) LP technique. Constructs were tested in an airflow model before and after cyclic loading which was designed to mimic postoperative swallowing. The cross-sectional area (CSA), peak translaryngeal airflow (L/s), and impedance (cmH2 0/L/s) were determined and compared between LP constructs before and after cycling. RESULTS: The mean CSA of the rima glottidis of the modified toggle LP constructs was 15.2 ± 2.6 cm2 before and 14.7 ± 2.6 cm2 after cyclic loading, and the mean CSA of the rima glottidis of the standard LP constructs was 16.4 ± 2.9 cm2 before and 15.7 ± 2.8 cm2 after cyclic loading. The modified toggle LP constructs had similar peak translaryngeal impedance before and after cyclic loading (p = .13); however, the standard LP constructs had higher peak translaryngeal impedance after cyclic loading (p = .02). CONCLUSION: The modified toggle and standard LP constructs had comparable airway mechanics in an ex-vivo model. CLINICAL SIGNIFICANCE: Further investigation is warranted to determine the extent to which the modified toggle LP technique restores normal airway function in horses with RLN.

Biomechanical properties of canine staphylectomies closed with barbed or smooth suture.

OBJECTIVE: To compare the duration of closure and biomechanical properties of staphylectomies closed with absorbable bidirectional barbed suture or smooth monofilament suture in a simple continuous or interrupted pattern STUDY DESIGN: Ex vivo study SAMPLE POPULATION: Soft palates (n = 60) harvested from mesaticephalic canine cadavers METHODS: One centimeter of tissue was excised from the caudal border of each soft palate, and the oral and nasopharyngeal mucosal surfaces were apposed with 2-0 bidirectional Quill Monoderm knotless closure device barbed suture (Q), 3-0 Monocryl in a simple continuous (MC) pattern, or 3-0 Monocryl in a simple interrupted (MI) pattern (n = 20 per group). Duration of closure was compared between groups. Tissues were tested under tension to failure, and mode of failure data were collected by video capture. RESULTS: Closure time was longer for MI closures than for Q and MC closures, with means of 259.9, 215.4, and 196.7 seconds, respectively (P < .0001). No difference was detected in yield force, force to first tissue rupture, maximum force, and energy required for yield and maximum force between groups. Energy to yield was 190.0, 167.8, and 188.95 N-mm for MI, Q, and MC closures, respectively. CONCLUSION: Biomechanical properties of staphylectomies closed with barbed or smooth sutures did not differ in this cadaveric model. CLINICAL SIGNIFICANCE: Barbed suture can be considered as an alternative for closure of canine staphylectomies. These results provide evidence to justify additional research to evaluate clinical outcomes in dogs undergoing staphylectomy.

Standing MRI lesions of the distal interphalangeal joint and podotrochlear apparatus occur with a high frequency in warmblood horses.

Foot pain is a common presenting complaint in Warmblood horses. The aim of this retrospective, cross-sectional study was to determine the spectrum of foot lesions detected by magnetic resonance imaging (MRI) in Warmblood horses used for dressage, jumping, and eventing. The medical records of 550 Warmblood horses with foot pain that were scanned using standing MRI were reviewed and the following data were recorded: signalment, occupation, lameness, diagnostic analgesia, imaging results, treatments, and follow-up assessments. Associations between standing MRI lesions and chronic lameness following treatment were tested. Abnormalities of the navicular bone (409 horses, 74%), distal interphalangeal joint (362 horses, 65%), and deep digital flexor (DDF) tendon (260 horses, 47%) occurred with the highest frequency. The following abnormalities were significantly associated (P < .05) with chronic lameness following conservative therapy: moderate to severe MRI lesions in the trabecular bone of the navicular bone, mild or severe erosions of the flexor surface of the navicular bone, moderate sagittal/parasagittal DDF tendinopathies, and moderate collateral sesamoidean desmopathies. Also, identification of concurrent lesions of the DDF tendon, navicular bone, navicular bursa, and distal sesamoidean impar ligament was associated with chronic lameness after conservative therapy. Development of effective treatment options for foot lesions that respond poorly to conservative therapy is necessary.

Partial arytenoidectomy in 14 standing horses (2013-2017).

OBJECTIVE: To report our experience with partial arytenoidectomy in sedated standing horses. STUDY DESIGN: Retrospective study. ANIMALS: Fourteen client-owned adult horses. METHODS: The medical records (2013-2017) of horses treated with unilateral partial arytenoidectomy while standing and sedated were reviewed. Demographics, endoscopic findings, previous treatments, and outcome after surgery were investigated and recorded. RESULTS: Thirteen horses had unilateral left-sided recurrent laryngeal neuropathy (RLN) and 1 horse had bilateral RLN. Five horses had a previous failed prosthetic laryngoplasty. Left-sided partial arytenoidectomy without mucosal closure was successfully completed in all horses under sedation and local anesthesia. Report of long-term outcome was obtained via telephone conversations for 12 horses, of which 9 also had an endoscopic reevaluation performed; 3 horses had granulomas at the surgical site, of which 2 eventually required a permanent tracheostomy. Nine horses returned to athletic use without respiratory noise, 2 horses returned to athletic use with noise during exercise that was reduced compared with preoperative levels, and 1 horse continued to be used as a broodmare. CONCLUSION: Partial arytenoidectomy in standing horses was achieved with adequate sedation and local anesthesia. CLINICAL SIGNIFICANCE: Partial arytenoidectomy on standing sedated horses could be considered as an alternative to eliminate the risks associated with general anesthesia.

Influence of barbed suture on leak pressures after double-layer inverting closure of cystotomy sites in sheep.

OBJECTIVE: To determine the influence of barbed suture on double-layer inverting closure of cystotomy sites in sheep. STUDY DESIGN: Ex vivo study. SAMPLE POPULATION: Urinary bladders harvested from ovine (n = 26) cadaveric specimens. METHODS: After collection and specimen preparation, a 3-cm-long incision was created on the ventral aspect of the urinary bladder. The cystotomy was repaired with barbed (n = 13) or nonbarbed analogous monofilament absorbable suture (n = 13) in a double-layer inverting suture pattern. Time required for closure in seconds was recorded for each test. Each bladder was connected to a pressure transducer to monitor intraluminal pressure during infusion with dyed Hartmann's solution until leakage occurred. Intraluminal pressure at time of initial leakage and leakage site were also recorded. Two-sample t tests were used to compare initial leakage pressure and closure time between the 2 types of suture (P = .05). RESULTS: The mean ( ± SD) leakage pressure of ovine urinary bladder incisions did not differ between closures with barbed sutures (42.3 ± 21.7 mmHg) and nonbarbed closures (32.5 ± 14.4 mmHg, P = .187). Cystorrhaphies were performed faster with barbed suture (307 ± 50 seconds) than with nonbarbed suture (390 ± 62 seconds, P = .001). CONCLUSION: The use of barbed suture did not affect mean leakage pressure of ovine urinary bladder incisions but decreased the time required to complete cystorrhaphies in this model. CLINICAL SIGNIFICANCE: This study provides evidence to support the use of knotless barbed suture for open ovine cystorrhaphies. Use of such suture for laparoscopic and laparoscopic-assisted procedures in sheep warrants caution until cyclic and in vivo testing is performed with appropriate laparoscopic instrumentation.

Comparison of complication rates following elective arthroscopy performed as inpatient versus outpatient surgery in horses.

OBJECTIVE To report complication rates following elective arthroscopy in horses and determine whether postoperative complication rates are higher for outpatient procedures, compared with inpatient procedures. DESIGN Retrospective cohort study. ANIMALS 357 client-owned horses that had undergone 366 elective arthroscopic procedures between January 2008 and February 2015. PROCEDURES Medical records were retrospectively reviewed. Data collected included signalment, travel time to the hospital, clinical signs, joints treated, lesions diagnosed, medications administered, anesthesia and surgery times, details of the procedure (including closure method and surgeons involved), and hospitalization status (inpatient or outpatient). Inpatients were horses that remained hospitalized overnight, and outpatients were horses that were discharged in the afternoon of the day of surgery. The collected data were analyzed along with follow-up information to identify factors associated with postoperative complications and potentially associated with hospitalization status. RESULTS Data were collected on 366 elective arthroscopic procedures (outpatient, n = 168 [46%]; inpatient, 198 [54%]). Complications that occurred included bandage sores, catheter problems, colic, diarrhea, postoperative discomfort, esophageal impaction, fever, incisional drainage, postanesthetic myopathy, persistent synovitis, persistent lameness, septic arthritis, and osteochondral fragments not removed during the original surgery. None of these complications were associated with hospitalization status (outpatient vs inpatient). However, Standardbreds were overrepresented in the outpatient group, and anesthesia and surgery times were longer for the inpatient group. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that outpatient elective arthroscopy in healthy horses could be performed safely and without a higher risk of complications, com pared with similar procedures performed on an inpatient basis.

Biomechanical evaluation of modified laryngoplasty by use of a toggle technique for stabilization of arytenoid cartilage in specimens obtained from equine cadavers.

OBJECTIVE To biomechanically compare modified and standard laryngoplasty constructs in monotonic load to failure and cyclic loading. SAMPLES 41 equine cadaveric larynges. PROCEDURES Laryngoplasty constructs were created by use of a standard technique on one side and a modified technique (with a toggle to anchor suture to the arytenoid cartilage) on the other side. For monotonic loading, laryngoplasty constructs were prepared and suture ends attached to a load frame; constructs then were loaded until mechanical failure. Mean load at failure and failure modes were compared between constructs. For cyclic loading, arytenoid cartilages were maximally abducted and constructs were circumferentially loaded for 10,000 cycles. Loss of arytenoid abduction was evaluated every 500 cycles with a subjective grading scale and objective change in rima glottidis cross-sectional area. RESULTS In monotonic loading, modified laryngoplasty constructs failed at a significantly higher mean ± SD load (191 ± 29 N) than did standard laryngoplasty constructs (91 ± 44 N). None of the modified laryngoplasty constructs failed by suture pull-through of the muscular process of the arytenoid cartilage, whereas most of the standard laryngoplasty constructs failed in that manner. In cyclic testing, 11 of 20 standard laryngoplasty constructs failed or achieved Dixon grade 3 abduction, whereas 0 of 20 modified laryngoplasty constructs failed. Modified laryngoplasty constructs lost significantly less rima glottidis cross-sectional area in circumferential testing, compared with loss for standard laryngoplasty constructs. CONCLUSIONS AND CLINICAL RELEVANCE The modified laryngoplasty technique was biomechanically superior to the standard laryngoplasty technique in this ex vivo study.

INJURIES OF THE SAGITTAL GROOVE OF THE PROXIMAL PHALANX IN WARMBLOOD HORSES DETECTED WITH LOW-FIELD MAGNETIC RESONANCE IMAGING: 19 CASES (2007-2016).

Sagittal groove injuries of the proximal phalanx are an important cause of lameness in performance horses. The purpose of this retrospective case series study was to describe standing low-field magnetic resonance imaging (MRI) characteristics of these injuries in a group of Warmblood horses. Horses with an MRI diagnosis of sagittal groove injuries involving the proximal phalanx and that had follow-up MRI and clinical outcome information were included. Findings from clinical examinations, diagnostic tests, and other imaging modalities were recorded. All MRI studies were retrieved for re-evaluation by an experienced, board-certified veterinary radiologist. A total of 19 horses met inclusion criteria. All horses had MRI lesions consistent with unilateral or bilateral sagittal groove injuries of the proximal phalanx and abnormal mineralization of the sagittal ridge of the third metacarpal/metatarsal bone. Fifteen horses (79%) had concurrent osteoarthritis of the affected metacarpophalangeal/metatarsophalangeal joint. Eighteen horses received conservative therapy and all horses still had osseous abnormalities detected at the time of follow-up MRI. Thirteen horses (68.5%) were still lame at the time of follow-up, whereas the other six horses (31.5%) had become sound and returned to the previous level of exercise. Findings indicated that, for mature Warmblood horses, acute or chronic injuries of the sagittal groove of the proximal phalanx may have variable standing low-field MRI characteristics. Based on this sample of 19 horses, findings also indicated that the prognosis for performance soundness in horses diagnosed with sagittal groove injury of the proximal phalanx and concurrent osteoarthritis is poor.

Effect of hoof boots and toe-extension shoes on the forelimb kinetics of horses during walking.

OBJECTIVE To determine and compare the effect of hoof boots (HBs) and shoes with a toe extension on stance duration, ground reaction force, and sole length in contact with the ground in nonlame horses during walking. ANIMALS 6 nonlame Standardbreds. PROCEDURES Force plate gait analyses of the forelimbs were performed while the horses were walking barefoot before manipulation of feet (baseline), while the horses were walking fitted with HBs, while the horses were walking shod with toe-extension shoes, and while the horses were walking barefoot after shoe removal. Horses underwent radiography of both forelimb feet to determine the sole length in contact with the ground when barefoot, wearing HBs, and shod with toe-extension shoes. Stance duration, ground reaction force, and sole length were compared among the various walking sessions. RESULTS Compared with baseline findings, stance duration increased significantly when horses were fitted with HBs (7%) or toe-extension shoes (5%). Peak forelimb ground reaction force was similar among walking sessions; however, time of braking force peak was significantly greater during the stance phase only when horses wore HBs. Also, the sole length in contact with the ground was significantly longer in horses fitted with HBs (14.3 cm) or shod with the toe-extension shoes (17.6 cm), compared with that for one of the barefoot hooves (12.7 cm). CONCLUSIONS AND CLINICAL RELEVANCE In nonlame horses, use of HBs prolonged the stance time and time of braking force peak, which is indicative of a slower deceleration phase during limb impact with the ground. Also, the use of HBs prolonged the deceleration phase of the stride and increased the sole length in contact with the ground.

SALINE ARTHROGRAPHY OF THE DISTAL INTERPHALANGEAL JOINT FOR LOW-FIELD MAGNETIC RESONANCE IMAGING OF THE EQUINE PODOTROCHLEAR BURSA: FEASIBILITY STUDY.

Abnormalities of the deep digital flexor tendon, navicular bone, and collateral sesamoidean ligament can be difficult to visualize using magnetic resonance imaging (MRI) if bursal fluid is absent. The use of saline podotrochlear bursography improves podotrochlear apparatus evaluation, however, the technique has disadvantages. The objective of this prospective feasibility study was to describe saline arthrography of the distal interphalangeal joint as an alternative technique for improving MRI visualization of the deep digital flexor tendon, navicular bone, collateral sesamoidean ligament, and podotrochlear bursa, and to compare this technique with saline podotrochlear bursography. Eight paired cadaver forelimbs were sampled. Saline podotrochlear bursography or saline arthrography techniques were randomly assigned to one limb, with the alternate technique performed on the contralateral limb. For precontrast and postcontrast studies using each technique, independent observers scored visualization of the dorsal aspect of the deep digital flexor tendon, palmar aspect of the navicular bone, collateral sesamoidean ligament, and podotrochlear bursa. Both contrast techniques improved visualization of structures over precontrast MR images and visualization scores for both techniques were similar. Findings from this study demonstrated that saline arthrography is feasible and comparable to saline podotrochlear bursography for producing podotrochlear bursa distension and separation of the structures of the podotrochlear apparatus on nonweight bearing limbs evaluated with low-field MRI. Clinical evaluation of saline arthrography on live animals is needed to determine if this technique is safe and effective as an alternative to saline podotrochlear bursography in horses with suspected pathology of the podotrochlear apparatus.

In vitro mechanical evaluation of equine laryngeal tie-forward constructs prepared with different suture materials and placement patterns.

OBJECTIVE: To compare the mechanical properties of laryngeal tie-forward (LTF) constructs prepared with different suture materials and suture placement patterns during single load to failure testing. SAMPLE: Larynges harvested from 50 horse cadavers and 5 intact horse cadavers. PROCEDURES: In vitro LTF constructs were created by a standard technique with polyester sutures, a standard technique with polyethylene sutures, a modified technique with metallic implants and polyester sutures, a modified technique with metallic implants and polyethylene sutures, or a modified tie-off technique with polyester sutures (10 of each type of construct). Mechanical properties including maximal load (N) at failure and failure mode were compared among constructs. Also, maximal loads at failure of the in vitro LTF constructs were compared with the loads exerted on the sutures tightened to achieve rostral laryngeal advancement in intact cadavers. RESULTS: Constructs prepared by a standard technique with polyethylene sutures had a significantly higher pull out strength than those prepared by a modified technique with metallic implants and either polyester or polyethylene sutures. For constructs prepared by a standard technique with polyethylene sutures or similarly placed polyester sutures, maximal load at failure did not differ but the failure mode did differ significantly. The load to failure for all in vitro constructs was higher than the maximal load measured during a range of motion test in intact horse cadavers. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that LTF procedures can be performed in live horses with any of the suture materials and techniques tested.

GROSS AND HISTOPATHOLOGIC CORRELATION OF LOW-FIELD MAGNETIC RESONANCE IMAGING FINDINGS IN THE STIFLE OF ASYMPTOMATIC HORSES.

With the recent introduction of a 0.25T rotating MRI system, clinical evaluation of the equine stifle joint is now possible in the average equine athlete. A recent publication described common abnormalities of horses with stifle lameness detected with a low-field MRI system; however, postmortem corroboration of the lesions detected was not possible. Therefore, our objective was to compare postmortem findings with low-field MRI findings in equine cadaver stifle joints. Ten fresh cadaver stifle joints from horses without clinical signs of stifle disease were evaluated using low-field MRI, gross dissection, and histopathology. In eight stifles, either the lateral or medial cranial meniscotibial ligament had an irregular shape, fiber separation, or moderate abnormal signal intensity (SI) on all sequences. In five stifles, the medial femoral condyle had articular cartilage fibrillation with or without an osteochondral defect over the weight bearing surface of the medial femoral condyle. All stifles had abnormal SI on all sequences within the patellar ligaments that corresponded with adipose tissue infiltrating between the collagen bundles. Other abnormalities identified included articular cartilage fibrillation of the tibial condyles in three stifles, and articular cartilage fibrillation with chondral defects in the patella in three stifles. All abnormalities detected with low-field MRI were corroborated by gross dissection. Findings from the current study supported the use of low-field MRI for detection of stifle joint lesions in horses and demonstrated that some stifle joint pathologies may be subclinical in horses.

Mechanical properties of various suture materials and placement patterns tested with surrogate in vitro model constructs simulating laryngeal advancement tie-forward procedures in horses.

OBJECTIVE: To compare the mechanical properties of laryngeal tie-forward (LTF) surrogate constructs prepared with steel fixtures and No. 5 braided polyester or braided polyethylene by use of a standard or a modified suture placement technique. SAMPLE: 32 LTF surrogate constructs. PROCEDURES: Surrogate constructs were prepared with steel fixtures and sutures (polyester or polyethylene) by use of a standard or modified suture placement technique. Constructs underwent single-load-to-failure testing. Maximal load at failure, elongation at failure, stiffness, and suture breakage sites were compared among constructs prepared with polyester sutures by means of the standard (n = 10) or modified (10) technique and those prepared with polyethylene sutures with the standard (6) or modified (6) technique. RESULTS: Polyethylene suture constructs had higher stiffness, higher load at failure, and lower elongation at failure than did polyester suture constructs. Constructs prepared with the modified technique had higher load at failure than did those prepared with the standard technique for both suture materials. All sutures broke at the knot in constructs prepared with the standard technique. Sutures broke at a location away from the knot in 13 of 16 constructs prepared with the modified technique (3 such constructs with polyethylene sutures broke at the knot). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested LTF surrogate constructs prepared with polyethylene sutures or the modified technique were stronger than those prepared with polyester sutures or the standard technique.

Effects of intrabursal administration of botulinum toxin type B on lameness in horses with degenerative injury to the podotrochlear apparatus.

OBJECTIVE: To determine the safety and short-term efficacy of intrabursal administration of botulinum toxin type B (BTXB) to alleviate lameness in horses with degenerative injury to the podotrochlear apparatus (PA). ANIMALS: 10 Quarter Horses with degenerative injury to the PA. PROCEDURES: Degenerative injury to the PA was confirmed with diagnostic analgesia and imaging. Then, BTXB (3.8 to 4.5 U/kg) was injected into the podotrochlear (navicular) bursa of each horse. Three horses were used in a safety evaluation. Subsequently, video recordings of lameness evaluations were obtained for 7 client-owned horses 5 days before (baseline) and 7 and 14 days after BTXB treatment and used to determine the effect of BTXB injection on lameness; 1 horse was removed from the study 8 days after BTXB treatment. Three investigators who were unaware of the treated forelimbs or time points separately reviewed the recordings and graded the lameness of both forelimbs of the horses. RESULTS: Improvement in lameness of the treated forelimbs was detected at 1 or both time points after BTXB administration in all horses. However, all horses had some degree of lameness at the end of the study. Two horses developed transient increases in lameness 48 to 72 hours after treatment; lameness resolved uneventfully. CONCLUSIONS AND CLINICAL RELEVANCE: Intrabursal injection of BTXB temporarily alleviated chronic lameness in horses with degenerative injury to the PA, without causing serious short-term adverse effects. Further investigation into the potential use of BTXB in horses affected by degenerative injury to the PA is warranted.