Heat hypersensitivity at a site proximal to a surgically induced osteochondral fracture in horses.

OBJECTIVE: To evaluate thermal nociceptive thresholds (TNTs) before and after inducing a standardized radiocarpal bone osteochondral fracture (OCF) in horses. STUDY DESIGN: Prospective, controlled, randomized, masked study. ANIMALS: A group of 10 Thoroughbred fillies aged 2 years. METHODS: Skin temperature and TNTs were measured on the skin over the triceps brachii muscle in both the thoracic limbs before (week 0) and weekly (weeks 1-8) after unilateral arthroscopic induction of a radiocarpal OCF (n = 4) or sham surgery (n = 6) followed by a standardized exercise programme. The contralateral, non-operated thoracic limb was used as a control within each horse. Percentage thermal excursion (%TE) defined as %TE = 100 ∗ (TNT - skin temperature)/(cut-off temperature - skin temperature) was calculated. Data were analysed with a mixed-effects model followed by Dunnett's and Tukey's tests for within and between-limbs comparisons, respectively; p < 0.05 was considered significant. RESULTS: Skin temperature in the control limb of OCF horses was significantly higher at week 7 than at week 0 (p = 0.0125). At week 1, TNTs and %TE values in operated limbs of OCF horses were significantly reduced compared with their baseline values at week 0 (p ≤ 0.0153) and their values in contralateral control limbs (p ≤ 0.0024) and operated limbs of sham-operated horses (p ≤ 0.0162). At week 2, TNTs and %TE values in operated limbs of OCF horses remained significantly reduced compared with values in operated limbs of sham-operated horses (p ≤ 0.0248). CONCLUSIONS AND CLINICAL RELEVANCE: Creation of an OCF in a radiocarpal bone induced transitory (<2 weeks) ipsilateral heat hypersensitivity proximal to the surgery site (skin over the triceps brachii muscle) in horses. Surgically induced OCF may cause somatosensory abnormalities consistent with secondary thermal hyperalgesia.

Second carpal bone slab fracture and subluxation of the middle carpal joint in a horse subsequent to arthrodesis of the carpometacarpal joint.

OBJECTIVE: To report complications of arthrodesis of the carpometacarpal (CMC) joint using a drilling technique in an adult horse. STUDY DESIGN: Case report. ANIMALS: Horse (n = 1). METHOD: A 12-year-old Quarter Horse mare with CMC osteoarthritis (CMC-OA) had arthrodesis under general anesthesia in right lateral recumbency. Under fluoroscopic guidance, a 4.5 mm drill bit was inserted at 3 drilling sites 5-6 cm into the CMC joint and was fanned 30-45° in the plane of the joint and 5-10° in the long axis of the limb to destroy articular cartilage and expose the subchondral bone. RESULTS: The horse presented 2 weeks after surgery for severe lameness of the operated limb. A slab fracture of the 2nd carpal bone (C2) and subluxation of the middle carpal (MC) joint was diagnosed. The horse was humanely euthanatized due to poor prognosis. CONCLUSION: The fanning technique of arthrodesis of the CMC joint may lead to fracture of carpal bones, joint instability, and MC joint subluxation. A balance between articular surface destruction and maintenance of joint stability should be achieved when using this technique.

Ex vivo evaluation of carpal flexion after partial carpal arthrodesis in horses.

OBJECTIVE: To determine degrees of flexion after arthrodesis of the antebrachiocarpal (ABC) joint, middle carpal (MC), and carpometacarpal (CMC) joints combined (MC/CMC), and carpometacarpal (CMC) joint alone. STUDY DESIGN: Ex vivo study. ANIMALS: Forelimbs (n = 9) from 2- to 10-year-old Quarter Horses (5), Thoroughbred (2), and American Paint Horse (2). METHODS: Using 2 locking compression plates, 3 partial carpal arthrodesis techniques were performed. Cables and deadweights were connected to limbs and each angle of flexion determined 3 times using a protractor and then averaged. Control measurements were obtained before and after arthrodesis, the techniques randomized with Latin square design. Descriptive data were analyzed with Levene's test, Q-Q plots, ANOVA, and Bonferroni test. RESULTS: Mean ± SD carpal flexion results were: controls 150° ± 8°, CMC arthrodesis 149° ± 9°, MC/CMC arthrodesis 43° ± 7.6°, and ABC arthrodesis 25° ± 6.3°. There was no significant reduction in flexion after a CMC arthrodesis compared with controls (P = .21), but there was after ABC (P < .001) and MC/CMC arthrodesis (P < .001), with the ABC arthrodesis significantly reduced compared with an MC/CMC arthrodesis (P < .001). CONCLUSIONS: Whereas CMC arthrodesis does not affect carpal flexion, CMC/MC and ABC arthrodesis markedly reduce the degree of carpal flexion.

Jejunal perforation due to porcupine quill ingestion in a horse.

An 8-month-old Andalusian filly was treated for jejunal perforations due to ingestion of a porcupine quill. During exploratory laparotomy, 2 separate stapled side-to-side jejunojejunal resection and anastomoses were performed. Post-operative complications after 2 years follow-up included mild incisional herniation following incisional infection and chronic intermittent colic.

Perforation jéjunale causée par l'ingestion d'une aiguille de porc-épic chez un cheval. Une pouliche d'Andalousie âgée de 8 mois a été traitée pour des perforations jéjunales causées par l'ingestion d'une aiguille de porc-épic. Durant une laparatomie exploratoire, deux résections et anastomoses jéjuno-jéjunales séparées et agrafées côte-à-côte ont été réalisées. Après un suivi de 2 ans, les complications postopératoires incluaient une légère hernie cicatricielle suite à une infection de l'incision et des coliques intermittentes chroniques.(Traduit par Isabelle Vallières).

Management and long-term outcome of partial glossectomy in 2 horses.

Records were reviewed for 2 horses with partial glossectomy, 1 traumatic and 1 elective. According to long-term follow-up by telephone, both horses had recovered well, experiencing only temporary difficulty while eating, and went on to be ridden successfully using mouth bits. Partial glossectomy, therefore, had a favorable prognosis in 2 performance horses.

Gestion et résultat à long terme de la glossectomie partielle chez 2 chevaux. Les dossiers ont été examinés pour 2 chevaux ayant subi une glossectomie partielle, 1 étant une glossectomie traumatique et 1 étant une glossectomie non urgente. Selon le suivi à long terme par téléphone, les deux chevaux se sont bien rétablis, ont éprouvé seulement une difficulté temporaire à manger et ont ensuite pu être montés avec succès en utilisant des mors. Par conséquent, une glossectomie partielle a présenté un pronostic favorable chez 2 chevaux de performance.(Traduit par Isabelle Vallières).

Infrared Spectroscopy of Synovial Fluid Shows Accuracy as an Early Biomarker in an Equine Model of Traumatic Osteoarthritis.

Osteoarthritis is a leading cause of lameness and joint disease in horses. A simple, economical, and accurate diagnostic test is required for routine screening for OA. This study aimed to evaluate infrared (IR)-based synovial fluid biomarker profiling to detect early changes associated with a traumatically induced model of equine carpal osteoarthritis (OA). Unilateral carpal OA was induced arthroscopically in 9 of 17 healthy thoroughbred fillies; the remainder served as Sham-operated controls. The median age of both groups was 2 years. Synovial fluid (SF) was obtained before surgical induction of OA (Day 0) and weekly until Day 63. IR absorbance spectra were acquired from dried SF films. Following spectral pre-processing, predictive models using random forests were used to differentiate OA, Sham, and Control samples. The accuracy for distinguishing between OA and any other joint group was 80%. The classification accuracy by sampling day was 87%. For paired classification tasks, the accuracies by joint were 75% for OA vs. OA Control and 70% for OA vs. Sham. The accuracy for separating horses by group (OA vs. Sham) was 68%. In conclusion, SF IR spectroscopy accurately discriminates traumatically induced OA joints from controls.

Plasma and Synovial Fluid Cell-Free DNA Concentrations Following Induction of Osteoarthritis in Horses.

Biomarkers for osteoarthritis (OA) in horses have been extensively investigated, but translation into clinical use has been limited due to cost, limited sensitivity, and practicality. Identifying novel biomarkers that overcome these limitations could facilitate early diagnosis and therapy. This study aimed to compare the concentrations of synovial fluid (SF) and plasma cell-free DNA (cfDNA) over time in control horses with those with induced carpal OA. Following an established model, unilateral carpal OA was induced in 9 of 17 healthy Thoroughbred fillies, while the remainder were sham-operated controls. Synovial fluid and plasma samples were obtained before induction of OA (Day 0) and weekly thereafter until Day 63, and cfDNA concentrations were determined using fluorometry. The SF cfDNA concentrations were significantly higher for OA joints than for sham-operated joints on Days 28 (median 1430 µg/L and 631 µg/L, respectively, p = 0.017) and 63 (median 1537 µg/L and 606 µg/L, respectively, p = 0.021). There were no significant differences in plasma cfDNA between the OA and the sham groups after induction of carpal OA. Plasma cfDNA measurement is not sufficiently sensitive for diagnostic purposes in this induced model of OA. Synovial fluid cfDNA measurement may be used as a biomarker to monitor early disease progression in horses with OA.

Healing of multiple fractured thoracic dorsal spinous processes in a Quarter horse.

A Quarter horse gelding sustained fracture and displacement of spinous processes T2-T10. Radiographic evidence of healing was seen 3 mo following injury, and at 2 years post-injury all spinous processes had healed and undergone partial re-alignment. This re-alignment has not been reported before.

Evaluation of a minimally invasive arthrodesis technique for the carpometacarpal joint in horses.

OBJECTIVE: To evaluate a minimally invasive technique for arthrodesis of the carpometacarpal (CMC) joint in horses. STUDY DESIGN: Experimental study. ANIMALS: Healthy horses (n=6). METHODS: A 5.5 mm, 3-drill tract arthrodesis technique was evaluated in 1 randomly selected CMC joint in each of 6 normal horses. Peak vertical ground reaction force (GRF) values were recorded before surgery and at 6, 8, and 12 months thereafter. Radiographic and clinical lameness scores were assigned at regular intervals until 12 months after surgery when the horses were euthanatized. Gross and histologic examinations were performed on the treated CMC joints. RESULTS: After surgery, all horses were lame. Clinical resolution of lameness occurred in 2 by 12 months. Mean peak vertical GRF values significantly differed between treated and nontreated limbs at all recorded time points after surgery. Radiographic scores significantly differed from day 0 at all times after surgery, but did not change significantly after 4 months. Intraarticular bony ankylosis only occurred in 2 horses, based on gross, histologic, and microradiographic examination of sagittal sections of the operated CMC joints. CONCLUSION: The 5.5 mm, 3-drill tract arthrodesis technique was considered successful in only 2 of 6 normal CMC joints treated. Greater articular damage may be necessary to achieve arthrodesis in normal horses. Better results may be achieved by technique modification or in horses affected by CMC osteoarthritis.

Successful treatment of hyperkalaemic periodic paralysis in a horse during isoflurane anaesthesia.

HISTORY: A 3-year-old, 400 kg, gelding Quarter Horse was presented for investigation of epistaxis. PHYSICAL EXAMINATION: The horse was bright, alert and responsive with rectal temperature, heart rate and respiration rate within normal limits. MANAGEMENT: During a second general anaesthetic for surgical treatment of guttural pouch mycosis by balloon-tipped catheter occlusion of the right major palatine artery and ligation of the right external carotid artery, signs consistent with hyperkalaemic periodic paralysis (HYPP) were exhibited. These included concurrent hyperkalaemia, hypercapnoea, sinus tachycardia, and muscle fasciculations in the presence of normothermia. Stress associated with an acute haemorrhage pre-operatively, and intra-operative hypercapnoea may have precipitated the episode. There were no signs of HYPP during a general anaesthetic, 1 week earlier, when an initial attempt at surgical treatment of guttural pouch mycosis was performed. Treatment consisted of fluid therapy and administration of calcium gluconate (0.1-0.2 mg kg(-1) minute(-1)), dextrose 5% (5 mL kg(-1) hour(-1)) and insulin (0.05 IU kg(-1)). Treatment resulted in the resolution of clinical signs and an uneventful recovery. FOLLOW-UP: The diagnosis of HYPP was confirmed by DNA analysis post-operatively. CONCLUSIONS: Clinical cases of intra-operative HYPP can present despite a previous history of uneventful general anaesthesia. Rapid diagnosis and treatment can result in the successful management of HYPP. This report documents an unusual presentation of HYPP, a disease that remains present in the Quarter Horse population.

Development of An Anybody Musculoskeletal Model of The Thoroughbred Forelimb.

Musculoskeletal injuries in horses are the main cause of retirement, rest, and death. To understand these injuries, it is necessary to study loads in muscles, tendons and ligaments. A musculoskeletal model makes it possible to consider all structures simultaneously and avoids invasive measurements. At present, most computational models of the equine limb described in the literature have been limited to the distal limb. The aim of this study was to create a preliminary musculoskeletal model of the whole equine forelimb and to run it with kinematic data collected during gait. The model was developed with the AnyBody Modelling System. It includes six limb segments, 11 muscle groups and 17 ligaments. Kinematic data were collected from the right forelimb of four Thoroughbreds at trot, right and left lead canter, and were then used in the model to compute sagittal plane joint excursions and ligament and tendon strains. The modelled joint excursions were in reasonable agreement with previous reports in the literature despite breed, gait and surface differences. Strain patterns of the tendons of the suspensory apparatus agreed with the literature, with maxima in mid-stance or at the end of stance. Strains in the distal palmar ligaments peaked in mid-stance, while strain in lacertus fibrosus peaked at the stance-swing transition. Tendon and ligament strains at canter were greatest when the measured forelimb was the trailing limb. Strain amplitudes varied against earlier models and these differences are discussed in relation to variations in methods, and especially in relation to attachment points of tendons and ligaments.

Treatment of carpometacarpal osteoarthritis by arthrodesis in 12 horses.

OBJECTIVE: To evaluate arthrodesis as a treatment for carpometacarpal joint osteoarthritis (CMC-OA). STUDY DESIGN: Case series. ANIMALS: Horses (n=12) with CMC-OA. METHODS: Arthrodesis was facilitated by insertion and fanning of a drill bit into the CMC joint at several (3-5) locations in 15 limbs. Follow-up radiographs were obtained for 7 horses (9 limbs). Outcome was determined by telephone survey of owners based on postoperative pain, return to use, appearance of the limb, and success of treatment. RESULTS: Postoperative pain was slight or moderate in 10 of 12 (83%) horses during the first 30 days, and 11 of 12 (92%) horses were markedly improved by 6 months and capable of returning to work. Radiographically 6 CMC joints had a bony ankylosis at follow-up whereas 3 did not (mean 8.7 months). On long-term follow-up (mean 28.6 months) all horses had reduced severity of lameness, 10 of 12 (83%) were considered "sound," 8 (67%) returned to their original activity, and all owners considered arthrodesis highly successful as a treatment. CONCLUSION: A drilling technique that produced CMC arthrodesis, allowed most horses to return to their original activity and was considered successful by all clients. CLINICAL RELEVANCE: Arthrodesis of the CMC joint should be considered a treatment option for CMC-OA.

Comparison of three drilling techniques for carpometacarpal joint arthrodesis in horses.

OBJECTIVE: To evaluate 3 drilling techniques for arthrodesis of the equine carpometacarpal (CMC) joint. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Cadaveric equine forelimbs (n=15). METHODS: Limbs were divided into 3 groups (5 limbs each) to evaluate 3 drilling techniques: (1) use of a 4.5 mm drill bit inserted into the joint through 4 entry points and moved in a fanning motion; (2) a 5.5 mm drill bit inserted through 2 entry points to create 3 nonfanned drill tracts (3 drill technique); and (3) a 4.5 mm drill bit used in a 3 drill technique. The CMC joint was disarticulated after drilling, and cartilage and subchondral bone damage evaluated visually and by gross and microradiographic examination using planimetry. RESULTS: Technique 1 produced significantly more damage of the proximal surface, but significantly less to the subchondral bone of the distal surface. Technique 1 produced the most damage to both the articular cartilage and subchondral bone of the total CMC joint than either of the 3 drill tract techniques; however, the difference between techniques 1 and 2 was not significant. Damage from technique 3 was significantly less than that with techniques 1 or 2. CONCLUSIONS: Techniques 1 and 2 produced the most cartilage and subchondral bone damage with technique 2 changes more equally distributed between proximal and distal joint surfaces. CLINICAL RELEVANCE: Technique 1 (fanning) and 2 (5.5 mm 3 drill tracts) may be preferable to achieve arthrodesis of the CMC joint. Morbidity and efficacy of these arthrodesis techniques need to be evaluated in vivo.

Carpometacarpal osteoarthritis in thirty-three horses.

OBJECTIVE: To describe signalment, clinical, and radiographic changes associated with carpometacarpal osteoarthritis (CMC-OA) and to report long-term outcome. STUDY DESIGN: Case series. ANIMALS: Horses (n=33) with CMC-OA. METHODS: Medical records (1992-2007) of horses diagnosed with CMC-OA were reviewed and signalment, clinical, and radiographic findings retrieved. Owners were contacted for information on the impact of lameness on intended use, response to treatment, progression of lameness, outcome, and owner satisfaction with response to treatment. RESULTS: CMC-OA identified in 39 limbs, occurred predominantly in middle-aged and older Quarter Horses and Arabians, and caused severe lameness that prevented normal use. Characteristic swelling was centered over the 2nd metacarpal bone/2nd carpal bone articulation. Radiographic changes consisted of proliferative new bone, narrowed joint space, and subchondral lysis. Of 20 horses with follow-up, 7 of 14 treated horses were euthanatized within 4 years and 4 of 5 nontreated horses within 3 years. Response to treatment was short lived and considered very poor by most owners. CONCLUSION: CMC-OA seemingly occurs primarily in Quarter Horses and Arabians in our region. Response to conservative treatment is very poor and short-lived with most horses being euthanatized. CLINICAL RELEVANCE: Conventional treatment methods are unsuccessful for treating CMC-OA.

Medical and surgical management of an intra-abdominal abscess of hepatic origin in a horse.

CASE DESCRIPTION: A 4-year-old Arabian-cross mare was examined because of a 48-hour history of pyrexia, lethargy, and signs of abdominal discomfort. CLINICAL FINDINGS: On initial evaluation, the horse was in good body condition, but febrile, tachycardic, tachypneic, and icteric and had signs of colic. Findings on CBC and serum biochemical analysis indicated marked systemic inflammation and hepatocellular damage. Serial abdominal ultrasonographic examinations revealed progressive, localized hepatic parenchymal abnormalities in the left ventral aspect of the abdomen in proximity to the left liver lobes, and eventual identification of an irregularly marginated, hyperechoic walled region of heterogenous echogenicity consistent with an encapsulated hepatic abscess. TREATMENT AND OUTCOME: Medical treatment was initiated with administration of doxycycline and flunixin meglumine. After 7 days, the horse's clinical signs and hematologic values improved. After 14 days, the horse was discharged from the hospital and prescribed continuation of doxycycline treatment for 14 days. One week following hospital discharge, the horse was reevaluated for recurrent signs of colic and pyrexia. The horse was sedated, and the region overlying the caudal aspect of the seventh rib was desensitized with an inverted L nerve block by local infiltration with 2% lidocaine. While the horse was standing and sedated, drainage of an encapsulated intra-abdominal abscess was followed by rib resection and removal of a portion of necrotic left lateral liver lobe. The development of a pneumothorax following rib resection represented the only major surgical complication. Twelve months later, the horse was clinically normal and had returned to its previous level of performance. CLINICAL RELEVANCE: Rib resection in standing sedated horses, together with appropriate medical management, should be considered an option for removal of well-encapsulated cranially located intra-abdominal abscesses that are adherent to the ventrolateral aspect of the body wall in horses.

Alcohol-facilitated ankylosis of the distal intertarsal and tarsometatarsal joints in horses with osteoarthritis.

OBJECTIVE: To assess the safety and efficacy of alcohol-facilitated ankylosis of the distal intertarsal (DIT) and tarsometatarsal (TMT) joints in horses with osteoarthritis (bone spavin). DESIGN: Prospective clinical trial. ANIMALS: 21 horses with DIT or TMT joint-associated hind limb lameness and 5 nonlame horses. PROCEDURES: 11 horses (group 1) underwent lameness, force-plate, and radiographic examinations; following intra-articular analgesia, lameness and force-plate examinations were repeated. Nonlame horses were used for force-plate data acquisition only. Following localization of lameness to the DIT and TMT joints, contrast arthrographic evaluation was performed; when communication with the tibiotarsal joint was not evident or suspected, 70% ethyl alcohol (3 mL) was injected. Group 1 horses underwent lameness, force-plate, and radiographic examinations every 3 months for 1 year. Ten other horses (group 2) underwent lameness and radiographic examinations followed by joint injection with alcohol; follow-up information was obtained from owners or via clinical examination. RESULTS: Significant postinjection reduction in lameness (after 3 days to 3 months) was evident for all treated horses. Twelve months after injection, 10 of 11 group 1 horses were not lame; lameness grade was 0.5 in 1 horse. Follow-up information was available for 9 of 10 group 2 horses; 7 were not lame, and 2 remained mildly lame (1 had a concurrent problem in the injected limb, and the other had DIT joint collapse that precluded needle entry). CONCLUSIONS AND CLINICAL RELEVANCE: Intra-articular alcohol injection in horses with bone spavin resulted in a rapid (usually within 3 months) reduction in lameness and joint space collapse.