Marcel Marcoux

Use of synovial fluid markers of cartilage synthesis and turnover to study effects of repeated intra-articular administration of methylprednisolone acetate on articular cartilage in vivo

In vivo the effects of intra‐articular (IA) corticosteroids on articular cartilage remain controversial. This study was designed to examine this issue using synovial fluid (SF) markers of cartilage metabolism. Paired radiocarpal joints, without clinical or radiographic signs of joint disease, were studied in 10 adult horses. Aseptic arthrocentesis was performed weekly for 13 weeks. IA injections of methylprednisolone acetate (MPA) into the treatment joint and the vehicle into the control joint were performed at weeks 3, 5 and 7. We used radioimmunoassays on SF samples which measure a keratan sulfate epitope (KS) and the 846 epitope on cartilage aggrecan (PG) and the C‐propeptide (CPII) of cartilage type II procollagen which is released following synthesis of this molecule. Gel chromatography was performed on selected SF samples to evaluate the sizes of SF PG molecules. The total joint KS and the 846 epitopes were both present on a heterogeneous population of mainly molecules which, from chromotographic analysis, appeared to be mainly fragments of the articular cartilage aggrecan. They were significantly elevated in MPA joints whereas CPII was significantly reduced compared to the control during the treatment period. These results indicate that the repeated use of IA MPA leads to a potentially harmful inhibition of procollagen II synthesis and an increased release of degradation products of the PG aggrecan from articular cartilage.

Use of transabdominal ultrasonography to determine the location of cryptorchid testes in the horse.

REASONS FOR PERFORMING STUDY Transrectal ultrasonography is a reliable technique to identify intra-abdominal testes, but can be hazardous or impractical in fractious, juvenile or small equids. The transabdominal approach therefore requires validation. OBJECTIVES To evaluate the sensitivity and specificity of transabdominal ultrasonography to localise cryptorchid testes. METHODS Thirty-eight horses admitted for cryptorchidism underwent transabdominal ultrasonography to locate errant testes. Location of the testes was confirmed during surgery (n = 37) or necropsy (n = 1). RESULTS Horses weighed 175-760 kg. Twenty-two testes were located within the abdomen, 19 in the inguinal space and 3 in a subcutaneous location. In 2 horses, a thick winter coat prevented adequate contact between the probe and the skin, and visualisation of their inguinal testis and one abdominal testis was missed during transabdominal ultrasonography. Excluding the 2 horses with excessive hair, the sensitivity of transabdominal ultrasonography to locate errant testes was 97.6% (93.2% when all horses were included), and its specificity 100%. CONCLUSIONS Transabdominal ultrasonography is a reliable, safe and immediate technique to diagnose cryptorchidism precisely in horses of all ages, sizes and temperaments. POTENTIAL RELEVANCE Transabdominal ultrasonography provides an immediate definitive diagnosis of adominal cryptorchidism and should enhance selection of an appropriate surgical approach for their removal.

Comparison of radiography and ultrasonography to detect osteochondrosis lesions in the tarsocrural joint: a prospective study.

REASONS FOR PERFORMING STUDY Lesions located on the medial malleolus of the tarsocrural joint can be difficult to image radiographically. Ultrasonography allows evaluation of articular cartilage and subchondral bone. OBJECTIVES To compare dorso30 degrees lateral-plantaromedial-oblique (DL-PIMO) and dorso45 degrees views to detect lesions on the medial malleolus, to validate the use of ultrasonography to show lesions in the tarsocrural joint and to compare its sensitivity to radiography. METHODS Tarsocrural joints (n=111) with osteochondrosis were evaluated ultrasonographically and radiographically prior to arthroscopic lesion debridement. A complete radiographic examination was made and the best view to detect each lesion recorded. Longitudinal and transverse ultrasonography of the dorsal aspect of the joint was performed and the best scan plane to image each lesion recorded. RESULTS There were 94 joints with lesions on the distal intermediate ridge of tibia, 24 with lesions on the medial malleolus, and 4 with lesions on the lateral trochlear ridge. The sensitivity of radiography to detect lesions on the medial malleolus and distal intermediate ridge of tibia was 71 and 96%, respectively. Eighty-two percent of lesions on the medial malleolus were better imaged on dorso30 degrees view. The sensitivity of ultrasonography to detect lesions on the medial malleolus and distal intermediate ridge of tibia was 83 and 98%, respectively. Ultrasonography was significantly more sensitive than radiography to detect lesions on the medial malleolus and distal intermediate ridge of tibia. CONCLUSION Dorso30 degrees lateral-plantaromedial-oblique view was the best to image lesions on the medial malleolus. Ultrasonography was a valuable diagnostic tool to diagnose lesions in the tarsocrural joint and was more sensitive than radiography for lesions located on the medial malleolus and distal intermediate ridge of tibia. CLINICAL RELEVANCE Radiographic examination should include a dorso30 degrees view for detection of lesions on the medial malleolus and ultrasonography should be considered to diagnose osteochondrosis in the tarsocrural joints.

Bronchoalveolar Lavage Fluid Cytology and Cytokine Messenger Ribonucleic Acid Expression of Racehorses with Exercise Intolerance and Lower Airway Inflammation

BACKGROUND There is limited information relating bronchoalveolar lavage (BAL) cytology and cytokine messenger ribonucleic acid (mRNA) expression in racehorses with inflammatory airway disease (IAD). HYPOTHESIS AND OBJECTIVE: We hypothesize that cytokine expression in BAL cells would correlate with cytology. Thus, we evaluated the mRNA expression of selected cytokines in BAL cells in racehorses with exercise intolerance and lower airway inflammation. ANIMALS Thirty-one client-owned Standardbred racehorses with exercise intolerance. METHODS Prospective, observational study. Cells were obtained by BAL, and mRNA expression of interleukin (IL)-1β, IL-4, IL-8, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ was determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). RESULTS Nine horses had normal BAL cell differential cytology (Controls), while 22 horses had evidence of IAD based on BAL fluid cytology. Relative expressions of TNF-α/glyceraldehyde 3-phosphate dehydrogenase (GAPDH; 0.0092 ± 0.010 versus 0.0045 ± 0.005, P= .034), IL-4/GAPDH (0.001 ± 0.002 versus 0.0003 ± 0.0003, P= .029), and IFN-γ/GAPDH (0.0027 ± 0.003 versus 0.0009 ± 0.001, P= .028) were greater in horses with IAD compared with controls. Furthermore, IL-4/GAPDH (0.001 ± 0.002 versus 0.0002 ± 0.0003, P < .0001) and IFN-γ/GAPDH (0.003 ± 0.003 versus 0.001 ± 0.001, P= .002) mRNA expression was increased in horses with increased metachromatic cell counts compared with horses with normal metachromatic cell counts. Only the mRNA expression of IL-1β/GAPDH (1.1 ± 0.7 versus 0.3 ± 0.3, P= .045) was increased with airway neutrophilia. CONCLUSIONS AND CLINICAL IMPORTANCE Differences in gene expression were associated with the presence of IAD and with specific cell types present in airway secretions of Standardbred racehorses with poor performance. These findings suggest that different pathophysiological pathways are implicated in IAD.

Evaluation of a thoracoscopic technique using ligating loops to obtain large lung biopsies in standing healthy and heaves-affected horses.

OBJECTIVE To evaluate use of pre-tied ligating loop to perform thoracoscopic, large lung biopsy in normal and heaves-affected horses. STUDY DESIGN Prospective clinical study. ANIMALS Normal (n=5) and heaves-affected (n=6) horses. METHODS Lung biopsies, 1 from each hemithorax, were collected thoracoscopically using a pre-tied ligating loop. Horses were either normal (C) or heaves-affected with the latter being in remission (Ha) for the initial biopsy and in exacerbation (Hs) for the 2nd biopsy. Clinical variables, PaO(2), and PaCO(2) were used to determine the effect of surgical biopsy. Postoperative pneumothorax was monitored by serial thoracic radiographic examinations. RESULTS Thoracoscopic lung biopsy (n=29, 22 procedures) was well tolerated by all horses. Complication rate was 31%, including 8 ligature slippage and 1 pulmonary hemorrhage. Intranasal oxygen was administered intraoperatively to 6 horses (2 C, 1 Ha, 3 Hs) with severe hypoxemia or labored breathing. There was a significant decrease in PaO(2) during surgery in horses not supplemented with oxygen. Postoperative pneumothorax (21/22 procedures) detected radiographically resolved within 3 weeks. CONCLUSION Thoracoscopic lung biopsy using pre-tied ligating loops was minimally invasive, relatively inexpensive, and fairly efficient. Heaves-affected horses tolerated the surgery well, even when in exacerbation; however, the technique was associated with non life-threatening complications in 31% of the biopsies, most of which required correction with additional ligating loops or more sophisticated instrumentation. CLINICAL RELEVANCE Using laparoscopic pre-tied ligating loop for thoracoscopically-assisted lung biopsy can be considered in horses with normal and impaired lung function but alternative instrumentation and access to intranasal oxygen must be available to the surgeon in case of complications.

Thoracoscopic lung biopsies in heaves-affected horses using a bipolar tissue sealing system.

Objective: To validate the use of the LigaSure™ Vessel Sealing System (LVSS) to perform thoracoscopic lung tissue biopsies in heaves-affected horses. Study design: Prospective clinical study. Animals: Heaves-affected horses (n=12). Methods: Lung biopsies (n=34) were collected with the LVSS (2–4 biopsies/horse) in horses with and without clinical signs of heaves. Thoracoscope (13th intercostal space [ICS]) and 2 instruments (between the 12–15th ICS) portals were used. Selected clinical and arterial blood gas variables were monitored. Postoperative pneumothorax was evaluated. Depth of thermal injury to the surrounding tissue and representativeness of the biopsies were determined. Results: Mean surgical time was 22.9±8.0 minutes. The complication rate was 5.6%, and primarily related to a focal inadequate sealing of the biopsy margin. Five horses in exacerbation required intraoperative intranasal O2. Mean PaO2 was significantly lower in heaves-affected horses with clinical signs compared with those without clinical signs. Postoperative pneumothorax was detected radiographically after 20 of the 34 procedures. One horse with clinical signs of heaves developed a fatal tension pneumothorax 5 days postoperatively despite close radiographic monitoring. Conclusion: Thoracoscopic lung biopsy using LVSS is a rapid and effective technique to harvest peripheral lung tissues from heaves-affected horses. Although the complication rate was tolerable, tension pneumothorax was a potential life-threatening complication because of incomplete lung sealing. Clinical Relevance: LVSS can be used with relative safety to perform thoracoscopic lung biopsy, but close postoperative monitoring is necessary to avoid tension pneumothorax.OBJECTIVE To validate the use of the LigaSure™ Vessel Sealing System (LVSS) to perform thoracoscopic lung tissue biopsies in heaves-affected horses. STUDY DESIGN Prospective clinical study. ANIMALS Heaves-affected horses (n=12). METHODS Lung biopsies (n=34) were collected with the LVSS (2-4 biopsies/horse) in horses with and without clinical signs of heaves. Thoracoscope (13th intercostal space [ICS]) and 2 instruments (between the 12-15th ICS) portals were used. Selected clinical and arterial blood gas variables were monitored. Postoperative pneumothorax was evaluated. Depth of thermal injury to the surrounding tissue and representativeness of the biopsies were determined. RESULTS Mean surgical time was 22.9±8.0 minutes. The complication rate was 5.6%, and primarily related to a focal inadequate sealing of the biopsy margin. Five horses in exacerbation required intraoperative intranasal O(2) . Mean PaO(2) was significantly lower in heaves-affected horses with clinical signs compared with those without clinical signs. Postoperative pneumothorax was detected radiographically after 20 of the 34 procedures. One horse with clinical signs of heaves developed a fatal tension pneumothorax 5 days postoperatively despite close radiographic monitoring. CONCLUSION Thoracoscopic lung biopsy using LVSS is a rapid and effective technique to harvest peripheral lung tissues from heaves-affected horses. Although the complication rate was tolerable, tension pneumothorax was a potential life-threatening complication because of incomplete lung sealing. CLINICAL RELEVANCE LVSS can be used with relative safety to perform thoracoscopic lung biopsy, but close postoperative monitoring is necessary to avoid tension pneumothorax.

Treatment of epiglottic entrapment by transnasal axial division in standing sedated horses using a shielded hook bistoury.

OBJECTIVES To report use of a shielded hook bistoury developed for correction of epiglottic fold entrapment in standing sedated horses. STUDY DESIGN Prospective clinical study. ANIMALS Standardbreds (n=8), 3-19 years of age. METHODS Epiglottic fold entrapment was corrected during standing sedation using a shielded hook bistoury passed nasally into the pharynx. Owners, trainers, and referring veterinarians were contacted by telephone to establish outcome. RESULTS Axial division of the entrapping epiglottic fold was successful in all horses. No short- or long-term complications occurred. Axial transection of the entrapping fold was performed rapidly (mean, 83 seconds between advancing the bistoury into the pharynx and transection of the entrapping fold). CONCLUSION Transnasal axial division of the aryepiglottic fold can be accomplished safely using the shielded hook bistoury. The shield mechanism minimizes the risk of injury from the cutting blade to adjacent structures.Objectives: To report use of a shielded hook bistoury developed for correction of epiglottic fold entrapment in standing sedated horses. Study Design: Prospective clinical study. Animals: Standardbreds (n=8), 3–19 years of age. Methods: Epiglottic fold entrapment was corrected during standing sedation using a shielded hook bistoury passed nasally into the pharynx. Owners, trainers, and referring veterinarians were contacted by telephone to establish outcome. Results: Axial division of the entrapping epiglottic fold was successful in all horses. No short- or long-term complications occurred. Axial transection of the entrapping fold was performed rapidly (mean, 83 seconds between advancing the bistoury into the pharynx and transection of the entrapping fold). Conclusion: Transnasal axial division of the aryepiglottic fold can be accomplished safely using the shielded hook bistoury. The shield mechanism minimizes the risk of injury from the cutting blade to adjacent structures.

Electrosurgical Tenoscopic Desmotomy of the Accessory Ligament of the Superficial Digital Flexor Muscle (Proximal Check Ligament) in Horses

OBJECTIVE To report a tenoscopic technique using monopolar electrosurgery to transect the accessory ligament of superficial digital flexor muscle (AL-SDFM) and outcome in 33 horses. STUDY DESIGN Case series. ANIMALS Horses (n=33). METHODS Medical files and surgery video recordings of horses that had AL-SDFM desmotomy performed by tenoscopy with monopolar electrosurgical electrodes were reviewed. RESULTS Of 33 horses, 24 were Standardbred racehorses with surgery performed bilaterally for superficial digital flexor tendonitis and 9 horses had flexural deformity. Severe (n=6) and mild (6) intrathecal hemorrhage was the most common intraoperative complication. Large intrathecal vessels including the nutrient artery were successfully electrocoagulated and AL-SDFM transection was completed. Clear/serosanguinous drainage from skin incisions was observed for 4.3±3.3 days (mean, SD). Protracted wound drainage for >4 days occurred in 10 horses, principally in the group treated for flexural deformities (P=.01). CONCLUSIONS Sixty-four AL-SDFM were transected under tenoscopic observation using monopolar electrodes. Electrocoagulation of large intrathecal vessels, including the nutrient artery, was possible in all cases and allowed completion of desmotomy. Postoperative wound care was similar to routine tenoscopy in most (70%) horses. Aseptic protracted wound drainage was observed in 30% of horses (principally those with flexural deformity), and led to a prolonged hospitalization.Objective: To report a tenoscopic technique using monopolar electrosurgery to transect the accessory ligament of superficial digital flexor muscle (AL-SDFM) and outcome in 33 horses. Study Design: Case series. Animals: Horses (n=33). Methods: Medical files and surgery video recordings of horses that had AL-SDFM desmotomy performed by tenoscopy with monopolar electrosurgical electrodes were reviewed. Results: Of 33 horses, 24 were Standardbred racehorses with surgery performed bilaterally for superficial digital flexor tendonitis and 9 horses had flexural deformity. Severe (n=6) and mild (6) intrathecal hemorrhage was the most common intraoperative complication. Large intrathecal vessels including the nutrient artery were successfully electrocoagulated and AL-SDFM transection was completed. Clear/serosanguinous drainage from skin incisions was observed for 4.3±3.3 days (mean, SD). Protracted wound drainage for >4 days occurred in 10 horses, principally in the group treated for flexural deformities (P=.01). Conclusions: Sixty-four AL-SDFM were transected under tenoscopic observation using monopolar electrodes. Electrocoagulation of large intrathecal vessels, including the nutrient artery, was possible in all cases and allowed completion of desmotomy. Postoperative wound care was similar to routine tenoscopy in most (70%) horses. Aseptic protracted wound drainage was observed in 30% of horses (principally those with flexural deformity), and led to a prolonged hospitalization.

Histological and biomechanical effects of palatal sclerotherapy in the horse using sodium tetradecyl sulfate

Palatal sclerotherapy using sodium tetradecyl sulfate has been suggested as a treatment for dorsal displacement of the soft palate in young Standardbred horses. The present study evaluated histological and biomechanical changes in the equine soft palate following trans-endoscopic treatment with a low dose of this compound. Two horses were euthanased and examined at 2 weeks and at 1, 2, 4 and 6 months post-sclerotherapy, while two further horses served as untreated controls. The technique was easily performed in all cases without major complications. On histological examination there was no evidence of palatal necrosis, inflammation or fibrosis in any of the treated or control animals. There was no variation in the density of palatal connective tissue between individuals, and on biomechanical assessment no significant difference in the stiffness of the palatal tissue was found between treated and control horses at any time. The lower dose of sodium tetradecyl sulfate used in this study relative to previous reports, might explain the absence of tissue alterations. This method of sclerotherapy did not alter the morphology or biomechanical properties of normal equine soft palates.

Effect of Presurgical Iodine‐Based Disinfection on Bacterial Colonization of the Equine Peripodal Region

OBJECTIVE To compare bacterial colonization after diluted iodine tincture or povidone iodine solution for presurgical disinfection of the equine peripodal region. STUDY DESIGN Complete block design. ANIMALS Five horses. METHODS Disinfection protocols using iodine tincture or povidone iodine solutions were tested on 5 pairs (n = 10) equine front feet. Iodine tincture was applied to the left feet and povidone iodine to the right feet. Fixed surfaces of the sole, frog, hoof wall, and peripodal skin were swabbed pre-preparation (T0), after a standard pre-disinfection step (T1), after short disinfection with a 4-minute application of 0.5% iodine tincture or povidone iodine (T2), and after long disinfection with 12-hour soaking in 0.25% iodine tincture or povidone iodine (T3). Quantitative bacteriology was performed on each swab. RESULTS The frog and sole were the most contaminated sites compared to hoof wall and skin at T0. Bacterial counts were significantly decreased at T2 for both solutions. Bacterial counts did not change significantly with iodine tincture at T3 but increased with povidone iodine compared to T2. Skin abrasions were detected on almost all feet but were subjectively more severe on iodine tincture-treated feet. CONCLUSION Soaking for 12 hours with either iodine tincture or povidone iodine is not recommended as these solutions damaged the skin and bacterial recolonization was noted with povidone iodine. Four-minute disinfection using either iodine tincture or povidone iodine (0.5% available iodine) is appropriate for presurgical preparation of the equine peripodal region.Objective To compare bacterial colonization after diluted iodine tincture or povidone iodine solution for presurgical disinfection of the equine peripodal region. Study design Complete block design. Animals Five horses. Methods Disinfection protocols using iodine tincture or povidone iodine solutions were tested on 5 pairs (n = 10) equine front feet. Iodine tincture was applied to the left feet and povidone iodine to the right feet. Fixed surfaces of the sole, frog, hoof wall, and peripodal skin were swabbed pre-preparation (T0), after a standard pre-disinfection step (T1), after short disinfection with a 4-minute application of 0.5% iodine tincture or povidone iodine (T2), and after long disinfection with 12-hour soaking in 0.25% iodine tincture or povidone iodine (T3). Quantitative bacteriology was performed on each swab. Results The frog and sole were the most contaminated sites compared to hoof wall and skin at T0. Bacterial counts were significantly decreased at T2 for both solutions. Bacterial counts did not change significantly with iodine tincture at T3 but increased with povidone iodine compared to T2. Skin abrasions were detected on almost all feet but were subjectively more severe on iodine tincture-treated feet. Conclusion Soaking for 12 hours with either iodine tincture or povidone iodine is not recommended as these solutions damaged the skin and bacterial recolonization was noted with povidone iodine. Four-minute disinfection using either iodine tincture or povidone iodine (0.5% available iodine) is appropriate for presurgical preparation of the equine peripodal region.