Comparison of three dorsal techniques for arthrocentesis of the distal interphalangeal joint in horses

OBJECTIVE: To compare 3 dorsal techniques for arthrocentesis of the distal interphalangeal joint in horses with regard to ease of performing the technique and to determine the role of operator experience in ease of performing these techniques. DESIGN: Observational study. Sample Population-Forelimbs from 17 equine cadavers and 12 horses (16 joints) undergoing arthrocentesis for therapeutic or diagnostic purposes. PROCEDURES: In both forelimbs from 7 of the equine cadavers, 3 arthrocentesis techniques (dorsal perpendicular, dorsolateral, and dorsal inclined) were performed in random order by a single experienced individual, and number of attempts needed to successfully insert the needle into the joint was recorded. For the forelimbs from the remaining 10 cadavers, veterinary students without experience in arthrocentesis performed each of the 3 arthrocentesis techniques (2 limbs/student) in random order, and number of attempts was recorded. In the clinical patients, arthrocentesis was performed by means of the dorsal inclined technique. RESULTS: For both the experienced individual and the veterinary students, number of attempts needed was significantly lower with the dorsal inclined technique than with the dorsal perpendicular or dorsolateral technique. Arthrocentesis was successful with the dorsal inclined technique in all 16 joints in the clinical patients; synovial fluid was recovered from 14 of the 16 joints. The procedure was well tolerated in all horses, except one that reacted to needle insertion. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the dorsal inclined technique for arthrocentesis of the distal interphalangeal joint was easier to perform than was the dorsal perpendicular or dorsolateral technique, regardless of experience level of the operator.     

Arthrocentesis of the temporomandibular joint in adult horses

OBJECTIVE: To develop a method for arthrocentesis of the temporomandibular joint in adult horses. ANIMALS: 7 equine cadaver heads and 6 clinically normal adult horses. PROCEDURE: Fluoroscopy, contrast radiography, and computed tomography were used on cadaver specimens to locate the temporomandibular joint, identify externally palpable landmarks for joint access, guide needle placement into the joint, and illustrate regional anatomy. The arthrocentesis technique was performed on 6 live healthy adult horses to determine efficacy and safety of this procedure. RESULTS: Externally palpable structures were identified as landmarks for temporomandibular arthrocentesis, including the lateral border of the condylar process of the mandible, the zygomatic process of the temporal bone, and the lateral pericapsular fat pad. Arthrocentesis was successful in all 6 joints in the live horses, and no complications developed. CONCLUSIONS AND CLINICAL RELEVANCE: The technique identified will improve the ability to examine and treat the temporomandibular joint in horses.     

The influence of repeated arthrocentesis and exercise on matrix metalloproteinase and tumour necrosis factor alpha activities in normal equine joints

REASONS FOR PERFORMING STUDY: Matrix metalloproteinases (MMPs) and tumour necrosis factor alpha (TNF-alpha) may be useful as biomarkers of joint disease or inflammation. However, activity of both MMPs and TNF-alpha in synovial fluid (SF) may be influenced by nonpathological factors such as arthrocentesis or exercise. OBJECTIVE: To investigate the influence of repeated arthrocentesis and exercise on MMP and TNF-alpha activities in SF from normal equine joints. METHODS: SF was collected from the left metacarpophalangeal, radiocarpal and tarsocrural joints of 16 horses. Eight of these horses were subsequently subjected to an exercise programme on a treadmill and 8 were box-rested as controls. Arthrocentesis was repeated 14, 145, 17 and 24 days after the start of the exercise programme. General MMP and TNF-alpha activities were determined in SF. RESULTS: Repeated arthrocentesis caused a gradual increase but the exercise regimen no significant increase in MMP activity. There was a significant increase in TNF-alpha activity in SF collected from horses 2 h after cessation of the exercise programme. CONCLUSIONS AND POTENTIAL RELEVANCE: When using MMPs as biomarkers for joint disease, at least 14 days should elapse after previous arthrocentesis before subsequent SF collection. Moderate exercise does not increase MMP activity in SF from normal joints and it may be possible to ignore this as a source of error in evaluating MMP activity in diseased joints.     

Comparison of ultrasound‐guided vs. ‘blind’ techniques for intra‐synovial injections of the shoulder area in horses: Scapulohumeral joint,bicipital and infraspinatus bursae

Reasons for performing study: Diagnosis and treatment of pathologies involving synovial structures in the shoulder region are technically difficult. Ultrasound‐guided (UG) injection techniques have been shown to be highly accurate, safe and reliable for various structures in human and equine patients. Objectives: To develop easy‐to‐use and reliable UG injection techniques for the infraspinatus bursa (IB), bicipital bursa (BB) and scapulohumeral joint (SHJ) and to compare them with conventional ‘blind’ methods. Methods: Eight pairs of equine shoulders were positioned on a computed‐tomography (CT) table with left and right shoulders randomly assigned to Operator A (UG) and Operator B (‘blind’). Contrast medium mixed with methylene blue was injected into the target structures. Time and number of attempts for correct needle placement and ease of injection were recorded. A CT scan of each shoulder was performed after every injection to evaluate the location of contrast material. Once injections and CT scans were completed, anatomic dissections were conducted. Statistical analysis was used to compare UG and ‘blind’ techniques with significance set at P<0.05. Results: Intra‐synovial injections using UG techniques were successful in all 24 synovial structures compared with 14/24 with conventional methods. The median number and range of needle repositioning to obtain accurate needle placement was 1 (1–2) for UG and 2 (1–4) for the ‘blind’ techniques. The median time and range required for accurate needle placement was 75.5 s (32–210 s) for UG and 43.5 s (11–140) for ‘blind’ technique. In 31% of all attempts, ease of injection was not indicative of successful intra‐synovial administration. Conclusions: Ultrasound‐guided injections of IB, BB and SHJ proved to be highly reliable and more accurate than conventional ‘blind’ techniques. Potential relevance: Ultrasound‐guided injection techniques may be of great help for equine practitioners in the diagnosis and treatment of pathologies involving synovial structures in the shoulder region. Further work is needed to confirm these results in clinical cases.     

Ultrasound-guided coxofemoral arthrocentesis in horses

REASON FOR PERFORMING STUDY: Coxofemoral joint pain is probably underestimated due to difficulties in identifying hip pain. The deep location of the joint and proximity of the sciatic nerve make arthrocentesis based on external landmarks a difficult and potentially risky procedure in mature horses. OBJECTIVES: To describe an ultrasound-guided injection technique of the coxofemoral joint in standing horses and to evaluate its accuracy and potential difficulties/complications. METHODS: Nine mature horses had both pelvic areas prepared for sterile ultrasound examination (3.5 MHz curvilinear probe). Coxofemoral joints were located and penetrated at their craniodorsolateral aspect under ultrasonographic guidance and injected with sterile contrast medium. A standing ventrodorsal radiographic view of each hemipelvis centred on the hip was obtained for each horse to assess the injection site. Horses were evaluated for 10 days following injection for possible complications. RESULTS: Intra-articular injection was successful in all 18 joints. The procedure was well tolerated by horses under minimal restraint. Mean +/- s.d. needle repositionings required before accurate placement was 1.5 +/- 1.3 per joint. Once the needle was in the joint, synovial fluid was obtained in 7/18 joints. Minimal periarticular contrast medium was detected in 2/18 joints. Mean +/- s.d. ultrasonographic examination time required for coxofemoral localisation, accurate needle positioning and injection was 4.3 +/- 2.1 min. No complications were observed in the 10 days following injection. CONCLUSION: The ultrasound-guided coxofemoral arthrocentesis is an accurate, reliable and safe technique that offers a real time evaluation of needle introduction into the deep and narrow coxofemoral joint space. POTENTIAL RELEVANCE: Although this technique remains to be tested on clinical cases, it is a promising tool to facilitate diagnosis of coxofemoral pain, septic arthritis or administration of intra-articular medication.     

Effect of intra-articular gentamicin sulfate on normal equine synovial membrane

Gentamicin sulfate (3 ml; 50 mg/ml) was administered intra-articularly into 30 normal equine radiocarpal joints after arthrocentesis. Arthrocentesis alone was performed on 10 normal radiocarpal joints. Synovial fluid evaluations and gross and microscopic examinations were performed on synovial fluid and synovial membrane of designated joints at selected daily intervals over a period of 10 days. Synovial fluid from gentamicin-injected joints had greater turbidity, higher RBC and WBC counts, and higher refractive indices than did joints not injected with gentamicin. The largest increases developed on days 1 or 2 after gentamicin injection, with mean total WBC, large mononuclear cell, small mononuclear cell, and polymorphonuclear cell counts of 23,860, 11,853, 857, and 11,150 cells/microliter, respectively. Arthrocentesis alone resulted in smaller increases in these counts. Microscopic changes seen in the synovial membrane of gentamicin-injected joints included edema, leukocytic infiltration, and loss of synovial lining cells. These inflammatory changes resolved within 7 days after gentamicin injection.     

A comparison of two techniques for arthrocentesis of the equine metacarpophalangeal joint

Because arthrocentesis of the metacarpophalangeal joint through the proximal palmar pouch may induce synovial haemorrhage, this study evaluated arthrocentesis through the lateral collateral sesamoidean ligament. The proximal palmar pouch and collateral sesamoidean ligament approaches were used in contralateral forelimbs to obtain paired initial synovial fluid samples from 16 horses 12 to 15 h before being killed. Synovial fluid samples also were collected from the same joints at necropsy and the subcutis, synovium and articular cartilage were evaluated. Metacarpophalangeal joint arthrocentesis through the collateral seamoidean ligament yielded fewer haemorrhagic synovial fluid samples with less subcutaneous and synovial inflammation, and also yielded 2 ml of synovial fluid more often than arthrocentesis through the proximal palmar pouch.     

COMPARISON OF ULTRASOUND‐GUIDED VS. STANDARD LANDMARK TECHNIQUES FOR TRAINING NOVICE OPERATORS IN PLACING NEEDLES INTO THE LUMBAR SUBARACHNOID SPACE OF CANINE CADAVERS

The standard technique for placing a needle into the canine lumbar subarachnoid space is primarily based on palpation of anatomic landmarks and use of probing movements of the needle, however, this technique can be challenging for novice operators. The aim of the current observational, prospective, ex vivo, feasibility study was to compare ultrasound‐guided vs. standard anatomic landmark approaches for novices performing needle placement into the lumbar subarachnoid space using dog cadavers. Eight experienced operators validated the canine cadaver model as usable for training landmark and ultrasound‐guided needle placement into the lumbar subarachnoid space based on realistic anatomy and tissue consistency. With informed consent, 67 final year veterinary students were prospectively enrolled in the study. Students had no prior experience in needle placement into the lumbar subarachnoid space or use of ultrasound. Each student received a short theoretical training about each technique before the trial and then attempted blind landmark‐guided and ultrasound‐guided techniques on randomized canine cadavers. After having performed both procedures, the operators completed a self‐evaluation questionnaire about their performance and self‐confidence. Total success rates for students were 48% and 77% for the landmark‐ and ultrasound‐guided techniques, respectively. Ultrasound guidance significantly increased total success rate when compared to the landmark‐guided technique and significantly reduced the number of attempts. With ultrasound guidance self‐confidence was improved, without bringing any significant change in duration of the needle placement procedure. Findings indicated that use of ultrasound guidance and cadavers are feasible methods for training novice operators in needle placement into the canine lumbar subarachnoid space.     

Influence of repeated arthrocentesis and exercise on synovial fluid concentrations of nitric oxide, prostaglandin E2 and glycosaminoglycans in healthy equine joints

REASONS FOR PERFORMING STUDY: The importance of osteoarthritis (OA) in the horse and the difficulty in its early diagnosis have led to a search for potential biomarkers of joint disease. If the levels of such markers are to be interpreted accurately, clinicians and researchers need to know whether they are influenced by environmental factors and/or interventions such as exercise and repeated arthrocentesis. OBJECTIVE: To investigate the influence of repeated arthrocentesis and exercise on nitric oxide (NO), prostaglandin E2 (PGE2) and glycosaminoglycan (GAG) concentrations in synovial fluid (SF) from normal equine joints. METHODS: SF was collected from the left metacarpophalangeal (MCP), radiocarpal and tarsocrural joints of 16 horses. Half of the horses were exercised and arthrocentesis was repeated 14, 14.5, 17 and 24 days after the start of the exercise programme, in both exercised and control horses. Nitric oxide was determined in SF from the MCP joint only and PGE2 and GAG concentrations were determined in SF from all joints. RESULTS: Repeated arthrocentesis caused an increase in NO concentration in the MCP joint on Day 145, in PGE2 concentrations in the radiocarpal and tarsocrural joints on Day 145 and the release of GAGs into SF of the MCP and radiocarpal joints on Day 17. Exercise resulted in an increase in PGE2 levels in all joints but did not influence the other parameters measured. POTENTIAL RELEVANCE: Repeated arthrocentesis is a potential confounding factor for the use of synovial NO, PGE2 and GAG concentrations as markers of joint disease. Based on this study, such a confounding effect can be avoided if one week or more separates arthrocentesis procedures. Moderate exercise causes a transient rise in PGE2 in SF.     

Description of a novel ultrasound guided peribulbar block in horses: a cadaveric study

BackgroundStanding surgery in horses combining intravenous sedatives, analgesics and local anaesthesia is becoming more popular. Ultrasound guided (USG) peribulbar nerve block (PB) has been described in dogs and humans for facial and ocular surgery, reducing the risk of complications versus retrobulbar nerve block (RB).ObjectiveTo describe a technique for USG PB in horse cadavers.MethodsLandmarks and PB technique were described in two equine cadaver heads (Phase 1), with computed tomography (CT) imaging confirming contrast location and spread. In Phase 2, ten equine cadaver heads were randomised to two operators naïve to the USG PB, with moderate experience with ultrasonography and conventional “blind” RB. Both techniques were demonstrated once. Subsequently, operators performed five USG PB and five RB each, unassisted. Contrast location and spread were evaluated by CT. Injection site success was defined for USG PB as extraconal contrast, and for RB intraconal contrast.ResultsSuccess was 10/10 for USG PB and 0/10 for RB (p < 0.001). Of the RB injections, eight resulted in extraconal contrast and two in the masseter muscle (p = 0.47).ConclusionsThe USG PB had a high injection site success rate compared with the RB technique; however, we cannot comment on clinical effect. The USG technique was easily learnt, and no potential complications were seen. The USG PB nerve block could have a wide application for use in horses for ocular surgeries (enucleations, eyelid, corneal, cataract surgeries, and ocular analgesia) due to reduced risk of iatrogenic damage. Further clinical studies are needed.     

Anatomy of the equine temporomandibular joint: study by gross dissection, vascular injection and section

REASONS FOR PERFORMING STUDY: The minute anatomy of the temporomandibular joint (TMJ) in horses is poorly documented in the literature. OBJECTIVES: To examine in detail the anatomy of the normal equine TMJ and the relationship of the joint to adjacent structures. METHODS: The anatomy of the TMJ was examined in 12 equidae using dissections, synovial and vascular injections and frozen and plastinated sections. Relevant structures were photographed. RESULTS: Rostral and caudal compartments were identified in the dorsal and ventral synovial pouches of the TMJ. Lateral and caudal ligaments were identified and attachments of the masticatory muscles over the TMJ were documented. Direct relationships between the TMJ and components of the ear were found, and the vascular supply described. CONCLUSIONS: This joint is related to some components of the ear as in man, and has its own peripheral vascular supply. Potential relevance: A knowledge of the detailed anatomy of the equine TMJ is a prerequisite to interpreting the imaging techniques, and will enable improved diagnosis of TMJ pathologies.     

Dorsolateral approach for arthrocentesis of the centrodistal joint in horses

OBJECTIVE: To develop a dorsolateral approach to the centrodistal (distal intertarsal) joint in horses and compare its success rate with that of the traditional medial approach in that joint. SAMPLE POPULATION: 25 cadaveric equine hind limbs, ultrasonographic images, and radiographic views of the tarsal region of 5 and 59 healthy horses, respectively, and 22 horses with a clinical indication for centrodistal joint centesis. PROCEDURES: The dorsolateral approach was established anatomically (3 cadaveric limbs), ultrasonographically (5 horses), and radiographically (59 horses). Centrodistal joint arthrocentesis was performed in 22 cadaveric hind limbs and 22 horses; the number of needle repositionings required for procedure completion via the medial (in vitro) and the dorsolateral approach (in vitro and in vivo) was determined. RESULTS: For the dorsolateral approach to the centrodistal joint, the injection site was 2 to 3 mm lateral to the long digital extensor tendon and 6 to 8 mm proximal to a line drawn perpendicular to the axis of the third metatarsal bone through the proximal end of the fourth metatarsal bone. The needle was directed plantaromedially (angle of approx 70 degrees from the sagittal plane). The number of needle repositionings required to complete centrodistal joint centesis via the dorsolateral and medial approaches was not significantly different. CONCLUSION AND CLINICAL RELEVANCE: In a clinical setting, the dorsolateral approach to the centrodistal joint in horses appears to have some advantages over the traditional medial approach. The success rate of arthrocentesis was similar via either approach, and palpation of the anatomic landmarks was easy.     

Cartilage-derived retinoic acid-sensitive protein in equine synovial fluid from healthy and diseased joints

Reasons for performing study: More sensitive and specific diagnostic methods for early detection of changes in the joint cartilage are needed. Cartilage‐derived retinoic acid‐sensitive protein (CD‐RAP) is a potential marker of cartilage synthesis and regeneration. This is the first study on equine CD‐RAP. Objectives: To evaluate the ability of a commercially available human sandwich ELISA assay to detect equine CD‐RAP in synovial fluid from healthy and diseased joints. Methods: Synovial fluid was collected from 28 horses with no signs of joint disease and from 5 with induced inflammatory arthritis. CD‐RAP concentrations were measured using a human CD‐RAP ELISA. Intra‐ and interassay imprecision of the assay were evaluated by multiple measurements on pools of equine synovial fluid. Assay inaccuracy was determined by linearity under dilution. Results: The assay showed moderate to large intra‐ and interassay variation when applied to equine synovial fluid. Equine CD‐RAP was detected in synovial fluid from healthy horses ranged at 8.2–52 ng/ml. Repeated arthrocentesis (after injection of isotonic saline), age, joint or gender did not significantly affect CD‐RAP concentrations. Twelve hours after intra‐articular injection of lipopolysaccharide, concentrations of CD‐RAP were significantly lower than after injection of isotonic saline and remained significantly lower until the end of the study at 144 h. Conclusion and potential relevance: The assay is suitable for longitudinal monitoring of CD‐RAP concentration in individual horses. Disease significantly influenced CD‐RAP levels. Similar to previous results obtained in man, CD‐RAP seems to be a marker of cartilage synthesis and/or regeneration in horses.     

Arthroscopic Anatomy of the Equine Temporomandibular Joint

OBJECTIVE: To develop an arthroscopic approach to, and describe the arthroscopic anatomy of, the equine temporomandibular joint (TMJ). STUDY DESIGN: Cadaveric study, after which the technique was tested in horses. ANIMALS OR SAMPLE POPULATION: Ten cadaveric equine heads and 5 normal horses (age, 5-13 years; weight, 425-545 kg). METHODS: Specimens or horses were positioned in right lateral recumbency. After fluid distention of the TMJ, arthroscopic portals were made in the dorsal compartment over the most prominent portion of the joint outpouching (caudodorsal approach) and in rostral and intermediate locations. The joint was explored and photographed. Positional changes in the mandible were made to determine if observation of the joint could be improved. Instrument portals were created to assess the feasibility of surgical arthroscopy. Cadaveric heads were dissected to assess iatrogenic damage, whereas experimental horses were observed for postoperative complications for 30 days. RESULTS: A caudodorsal arthroscopic approach provided the best evaluation of the dorsal compartment of the TMJ. The approach allowed observation of the rostral and caudal synovial pouches and the lateral aspect of the joint including the articular disc. Examination of the medial aspect of the joint was limited to the most rostral and caudal aspects. Access to the lateral aspect of the ventral compartment of the TMJ was precluded by the position of the transverse facial artery and vein. In specimens, iatrogenic damage was minimal and limited to the articular fibrocartilage, articular disc, and penetration of the parotid salivary gland. If the latter also occurred in horses, no adverse effects were noted. In horses, mild fluid extravasation occurred and resolved within 1 day. All horses ate normally after surgery but had periarticular swelling and mild pain upon palpation of the TMJ for 2 days. CONCLUSIONS: A caudodorsal arthroscopic approach to the TMJ allowed adequate observation of the lateral aspect of the dorsal compartment of the joint. Access to the ventral compartment was precluded by the location of the transverse facial artery and vein. CLINICAL RELEVANCE: Conditions affecting the lateral and caudal aspects of the dorsal compartment of the TMJ should be visible by arthroscopy.     

Collagenase-1 (MMP-1) activity in equine synovial fluid: influence of age, joint pathology, exercise and repeated arthrocentesis

REASONS FOR PERFORMING STUDY: Matrix metalloproteinases (MMPs) are considered candidate biomarkers for both physiological and pathological tissue remodelling because of their key role in articular cartilage homeostasis. As disruption of the collagenous architecture is thought to be pivotal in chronic degenerative diseases such as osteoarthritis (OA), the collagenases form an interesting subset of the MMPs. The significance of any biomarker in synovial fluid (SF) can be assessed properly only when fluctuations in patterns induced by physiological processes such as development and growth, and by external influences and interventions such as exercise and repeated arthrocentesis, are known and taken into account. OBJECTIVES: To investigate the activity of MMP-1 in equine SF at different stages of development and in joints affected by OA, and the influence of exercise and repeated arthrocentesis thereon. METHODS: MMP-1 activity was determined in SF of normal joints of fetal, juvenile and mature horses, and in SF of horses suffering from OA, using an internally quenched fluorogenic peptide substrate. MMP-1 activity was also measured in SF from horses subjected to an exercise regimen and those subjected to repeated arthrocentesis. RESULTS: An age-related decline in the SF levels of active MMP-1 was observed. MMP-1 activity was 15-fold higher in fetal than in juvenile animals, which showed significantly higher MMP-1 activity levels than mature horses. In SF of OA joints, MMP-1 activity was increased. Exercise did not affect MMP-1 activity in SF, but repeated arthrocentesis (within 60 h) increased MMP-1 activity significantly. CONCLUSIONS: The high MMP-1 activity in SF of young individuals parallels the high metabolic activity occurring during rapid growth and differentiation at early age. The elevated MMP-1 activity in SF of OA joints probably reflects pathological matrix degradation, confirming the potential of MMP-1 to serve as a biochemical marker for early joint disease. Moderate exercise is not likely to influence the outcome of MMP-1 activity measurements in equine SF, but arthrocentesis should be taken into account as a possible confounding factor. POTENTIAL RELEVANCE: Given the crucial role of the collagen matrix for tissue integrity, MMP-1 activity may be a useful tool in diagnostic, therapeutic or prognostic studies in horses suspected of OA. However, care should be taken to exclude fluctuations in MMP-1 activity induced by physiological processes such as development and growth, and by interventions such as repeated arthrocentesis.     

ULTRASOUND‐GUIDED CERVICAL CENTESIS TO OBTAIN CEREBROSPINAL FLUID IN THE STANDING HORSE

Horses with intracranial lesions and severe ataxia are not good anesthesia candidates; however, only one method to obtain cerebrospinal fluid (CSF) from the cervical region in a standing horse has been reported. This method is not performed routinely due to the difficulty for sample acquisition. Our hypothesis is that standing cervical centesis can be performed in horses without complication. Ultrasound‐guided centesis of the CSF between C1 and C2 in 11 clinically normal horses and two horses with neurologic signs were performed. Horses were sedated and ultrasound was used to identify the subarachnoid space and spinal cord between C1 and C2. With ultrasound guidance, a needle was introduced into the dorsal aspect of the subarachnoid space using a lateral approach. Ten milliliters of CSF was obtained and analyzed. Two normal horses in this study had moderate red blood cell contamination in the CSF (940 and 612 RBC/μl). One horse had 11 RBC/μl and the remaining horses had <4 RBC/μl. The total procedure time was approximately 2 min. No reaction was observed and no complications were detected up to 48 h after the procedure. Ultrasound‐guided centesis between C1 and C2 is a rapid procedure that causes minimal to no reaction in standing, sedated horses used in this study. The use of ultrasound to guide a standing C1–2 centesis of the subarachnoid space provides an additional route to obtain CSF for analysis in the equine patient.     

Effect of Repeated Arthrocentesis on Cytology of Synovial Fluid

Repeated arthrocentesis is necessary to diagnose and monitor the evolution of joint diseases, but the procedure may worsen any inflammation and lead to an alteration in synovial fluid. The aim of this study was to determine the effect of repeated arthrocentesis on synovial fluid cytology in healthy horses with normal joints. The experimental study was approved by Ethics Committee (University of Pisa, Italy). Four horses were enrolled in this study on the basis of inclusion criteria and underwent repeated arthrocentesis of the intercarpal joint of both left and right forelimbs. The synovial fluid samples were processed for total protein concentration, total nucleated cell count, and differential leukocyte count. Data distribution was performed with the Komolgorov–Smirnov test, and a Friedman test for repeated measures and Dunn's test as post hoc were performed in order to verify differences related to sampling times comparing each time point. Significance was set at P < .05. All horses remained free of lameness throughout the study period. Statistical differences were found for macrophage and lymphocyte related to sampling time. Our results support the finding that repeated arthrocentesis does not induce detectable synovial fluid alterations. Although mild statistically significant changes in macrophage and lymphocyte populations were found, the values were always within normal ranges, suggesting that these changes were not clinically significant. Moreover, the cytologic alterations rapidly solved. In conclusion, repeated arthrocentesis does not cause long term and clinically relevant alterations in synovial fluid cytology in healthy horses with normal joints.     

Clinical effects of detomidine with or without atropine used for arthrocentesis in horses

The effectiveness of detomidine with or without atropine sulfate premedication in producing sedation and analgesia for arthrocentesis was studied in 12 horses. The effects were evaluated by monitoring heart and respiratory rates, borborygmi, distance from the lower lip to the floor, systolic blood pressure, and response to needle insertion. Either atropine or saline (as a placebo) was administered immediately prior to detomidine. All drugs were administered intravenously. Measurements were taken prior to drug injection and at 1, 5, 10, 15, 20, 25, 30, 40, 50, 60, 120, 180 and 240 minutes postinjection. Detomidine with atropine resulted in significantly higher heart rates than detomidine without atropine for the three hours of observation. Borborygmi were significantly decreased for four hours following detomidine with atropine and for three hours following detomidine without atropine, when compared to preinjection levels. Systolic blood pressure was significantly increased for 15 minutes following detomidine and atropine compared to the preinjection level. The head was markedly lowered for 60 minutes with either treatment. Atropine prevented the bradyarrhythmia and bradycardia induced by detomidine, but it induced a tachycardia. A satisfactory response for needle insertion and adequate synovial fluid aspiration was achieved in 95% of the trials with detomidine, with or without atropine sulfate premedication. The results suggest that, although atropine prevents bradyarrhythmia and bradycardia following detomidine, administering detomidine without atropine is satisfactory for arthrocentesis in untrained horses.     

Concentrations of serum amyloid A in serum and synovial fluid from healthy horses and horses with joint disease

OBJECTIVE: To determine serum amyloid A (SAA) concentrations in serum and synovial fluid from healthy horses and horses with joint disease and assess the effect of repeated arthrocentesis on SAA concentrations in synovial fluid. Animals-10 healthy horses and 21 horses with various types of joint disease. PROCEDURES: Serum and synovial fluid samples were obtained from each horse. In 5 of the 10 healthy horses, arthrocentesis was repeated 9 times. Concentrations of SAA were determined via immunoturbidometry. RESULTS: Serum and synovial fluid SAA concentrations were less than the assay detection limit in healthy horses and did not change in response to repeated arthrocentesis. Synovial fluid SAA concentrations were significantly higher in horses with suspected bacterial joint contamination or infectious arthritis, or tenovaginitis than in healthy controls, and serum concentrations were significantly higher in horses with infectious conditions than in the other groups. Neither serum nor synovial fluid SAA concentrations in horses with low-inflammation joint conditions differed significantly from those in healthy controls. Concentrations of SAA and total protein in synovial fluid were significantly correlated. CONCLUSIONS AND CLINICAL RELEVANCE: Synovial fluid SAA concentration was a good marker of infectious arthritis and tenovaginitis and appeared to reflect changes in inflammatory activity. The advantages of use of SAA as a marker include the ease and speed of measurement and the fact that concentrations in synovial fluid were not influenced by repeated arthrocentesis in healthy horses. Further study of the SAA response in osteoarthritic joints to assess its usefulness in diagnosis and monitoring of osteoarthritis is warranted.