Absolute and relative cell counts for synovial fluid from clinically normal shoulder and stifle joints in cats

OBJECTIVE: To determine absolute and relative cell counts for synovial fluid from grossly, radiographically, and histologically normal shoulder and stifle joints in healthy cats. DESIGN: Clinical study. ANIMALS: 52 cats scheduled to be euthanatized for unrelated reasons. PROCEDURE: Arthrocentesis of the shoulder and stifle joints was performed bilaterally, and synovial fluid was analyzed for absolute WBC count, WBC morphology, and percentages of neutrophils and mononuclear cells. Joints were examined grossly and radiographically, and synovial membrane specimens were submitted for histologic examination. Synovial fluid samples that were contaminated with blood and samples from joints with any gross, radiographic, or histologic abnormalities were excluded. RESULTS: 82 of the 208 synovial fluid samples were excluded because abnormalities were identified during physical examination; the volume of fluid obtained was insufficient for analysis; there was evidence of blood contamination; or the joint had gross, radiographic, or histologic abnormalities. Median WBC count for the remaining 126 synovial fluid samples was 91 cells/microL (96.4% mononuclear cells and 3.6% neutrophils); WBC count was not significantly different between left and right joint samples or between shoulder and stifle joint samples. Body weight was associated with synovial fluid WBC count, with WBC count increasing as body weight increased. Sixteen of the 52 (30%) cats had radiographic evidence of osteoarthritis involving at least 1 joint. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that synovial fluid can be obtained reliably from shoulder and stifle joints in cats.     

The synovial response to exogenous phospholipid (synovial surfactant) injected into the equine radiocarpal joint compared with that to prilocaine, hyaluronan and propylene glycol

AIMS: To determine the effects of the intra-articular injection of surface-active phospholipid in a propylene glycol carrier on synovial fluid composition and joint function of horses, and to compare these effects with those observed after the intra-articular administration of prilocaine, hyaluronan and propylene glycol alone. METHODS: Twenty-four horses were randomly allocated to four treatment groups: Group 1 100 mg of surface-active phospholipid in 1 ml of propylene glycol; Group 2 1 ml of propylene glycol; Group 3 10 ml of prilocaine; Group 4 2 ml of hyaluronan. Left radiocarpal joints were injected with the treatments and the right radiocarpal joints were injected with volume-matched saline as controls. Examinations for lameness, arthrocenteses and synovial fluid analyses were performed before and at 1, 3 and 7 days after injection. RESULTS: No horses became lame but treated joints temporarily developed mild to moderate effusions. Synovial fluid analyses indicated significantly greater inflammation in treated compared to control joints and this difference was greatest 24 hours after injection. There were no differences between the four treatments based on synovial fluid analysis except for neutrophil counts and alkaline phosphatase activities, which were significantly higher in prilocaine-treated joints. CONCLUSION: In horses, the intra-articular injection of surface-active phospholipid in a propylene glycol carrier induces clinically insignificant, temporary abnormalities in synovial fluid. Surface-active phospholipid was no more injurious to the synovium than prilocaine or hyaluronan. None of the agents used in this experiment caused lameness when injected into the joints of horses. RELEVANCE: This dose and formulation appear suitable for use in future experiments investigating the efficacy of surface-active phospholipid in the treatment or prevention of osteoarthritis in horses.     

Effects of intra-articular administration of dimethylsulfoxide on chemically induced synovitis in immature horses

The effects of intra-articular administration of dimethylsulfoxide (DMSO) on chemically induced synovitis in the middle carpal joint of 6 weanling horses were evaluated. Following aseptic collection of synovial fluid, the middle carpal joint of each forelimb was injected with 50 mg of Na-monoiodoacetate to induce synovitis. Eight days after injection, synovial fluid was obtained and the right middle carpal joints were injected with 2 ml of 40% DMSO in lactated Ringer solution. The corresponding joints of the left limb (control) were injected with 2 ml of lactated Ringer solution. Sampling and treatments were repeated on post-injection days 11 and 14, for a total of 3 treatments. Horses were visually evaluated daily for lameness and joint effusion. Synovial fluid was evaluated for color and clarity, differential and total WBC count, total protein content, and hyaluronic acid concentration. The Kaegi gait analysis system provided an objective assessment of lameness prior to inducing synovitis, again on day 7, and on day 17. At necropsy (day 17), synovial fluid, synovial membrane, and articular cartilage specimens were collected. Joint effusion was evident 12 hours after injection of Na-monoiodoacetate in all joints. Mild lameness was evident at 24 hours; however, the lameness resolved by 72 hours. Objective assessment of lameness did not reveal significant differences between treatment or control limbs. Hyaluronic acid concentrations increased significantly (P = 0.023) above baseline values in most joints over the study period. Synovial fluid WBC counts increased significantly (P = 0.002) following Na-monoiodoacetate injection and remained significantly (P = 0.002) above baseline values throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of synovial fluid from clinically normal alpacas and llamas

OBJECTIVE: To establish reference range values for synovial fluid from clinically normal New World camelids. ANIMALS: 15 llamas and 15 alpacas. PROCEDURE: Llamas and alpacas were anesthetized with an IM injection of a xylazine hydrochloride, butorphanol tartrate, and ketamine hydrochloride combination. Synovial fluid (1 to 2 ml) was obtained by aseptic arthrocentesis from the radiocarpal and tarsocrural joints. Synovial fluid evaluation included determination of total nucleated cell count (NCC), absolute number and percentage of polymorphonuclear (PMN) and mononuclear leukocytes, total protein, and specific gravity. RESULTS: Synovial fluid evaluation revealed a total NCC of 100 to 1,400 cells/microl (mean +/- SD, 394.8+/-356.2 cells/microl; 95% confidence interval [CI], 295.2 to 494.6 cells/microl). Mononuclear leukocytes were the predominant cell type with lymphocytes, composing 50 to 90% (mean, 75.6+/-172%; 95% CI, 70.8 to 80.4%) of the mononuclear leukocytes. Approximately 0 to 12% (mean, 1.3+/-2.9%; 95% CI, 0.49 to 2.11%) of the cells were PMN leukocytes. Total protein concentrations ranged from 2.0 to 3.8 g/dl (mean, 2.54+/-0.29 g/dl; 95% CI, 2.46 to 2.62 g/dl); the specific gravity ranged between 1.010 and 1.026 (mean, 1.017+/-0.003; 95% CI, 1.016 to 1.018). CONCLUSION AND CLINICAL RELEVANCE: In llamas and alpacas, significant differences do not exist between species or between limbs (left vs right) or joints (radiocarpal vs tarsocrural) for synovial fluid values. Total NCC and absolute number and percentage of PMN and mononuclear leukocyte are similar to those of other ruminants and horses. However, synovial fluid total protein concentrations in New World camelids are high, compared with other domestic species.     

The effect of implanting gentamicin-impregnated polymethylmethacrylate beads in the tarsocrural joint of the horse

OBJECTIVE: To determine the effect of intra-articular gentamicin-impregnated polymethylmethacrylate (PMMA) beads inserted in the equine tarsocrural joint on the synovial fluid, synovial lining, and cartilage, and to determine the peak and sustainable gentamicin concentrations in synovial fluid and plasma. STUDY DESIGN: Pharmacokinetic, cytologic, and histologic study of the effect of gentamicin-impregnated PMMA on normal equine tarsocrural joints. ANIMALS: Five healthy adult horses. METHODS: Gentamicin-impregnated PMMA bead strands (3 strands each of 40 beads, with each strand containing 100 mg gentamicin) were surgically inserted into one radiographically normal tarsocrural joint in 5 horses. Each horse had both joints flushed with 1 L of lactated Ringer's solution before bead administration. Synovial fluid total protein concentration, white blood cell (WBC) count, gentamicin concentration, synovial histology, cartilage integrity, and cartilage glycosaminoglycan (GAG) concentrations were determined. RESULTS: Gentamicin concentration (mean +/- SEM peak concentration, 27.9 +/- 2.27 microg/mL) occurred in the first 24 hours and remained above 2 microg/mL for 9 days. Gentamicin concentrations in control joints and the plasma remained below detectable levels. The synovial fluid WBC count for treated joints was increased compared with control joints for 72 hours, but was similar at day 6. The synovial protein concentration in gentamicin-treated joints remained increased for 21 days. Synovium in treated joints had diffuse synovitis, whereas control joints had less fibrovascular proliferation. Superficial cartilage erosion was present in all treated joints. There was no difference in the GAG content of treated and control joint cartilage. CONCLUSIONS: Short-term implantation of gentamicin (300 mg)-impregnated PMMA beads can provide therapeutic levels of gentamicin (>2 microg/mL) in the normal tarsocrural joint for 9 days; however, gentamicin-impregnated PMMA beads induce synovitis and superficial cartilage erosion. CLINICAL RELEVANCE: Temporary intra-articular administration of antibiotic-impregnated PMMA may be an effective way to treat septic joints that require constant high concentrations of antibiotics.     

Examination of body fluids

In dogs, the pericardial sac contains about 0.3 ml, and the pleural and peritoneal cavities 0-15 ml of clear, straw-colored fluid of pH 7.4, specific gravity 1.016, protein content less than 3.0 g/dl and cell count less than 3000/microliter. Fat can be cleared from chylous fluid with NaOH and ether. Inflammation is indicated by a cell count greater than 3000/microliter. Amylase levels in peritoneal fluid are elevated in necrotizing pancreatitis. The percentage of polymorphonuclear WBC exceeds 50% in bacterial inflammations. Normal joints contain less than 1 ml highly viscid, clear or straw-colored synovial fluid with less than 1000 nucleated cells/microliter. Synovial fluid becomes flocculent and less viscid in septic and occasionally in immune-mediated arthritis, often with cell counts greater than 75,000/microliter, with 75-90% polymorphonuclear WBC. Cerebrospinal fluid is normally acellular, clear and colorless but may be red, yellow or brown with intracranial hematomas. Viral or aseptic meningitis is characterized by mononuclear cell counts of less than 500/microliter. In acute bacterial meningitis, nucleated cell counts are greater than 1000/microliter, with most being polymorphonuclear WBC. Gram staining of cerebrospinal fluid is not useful.     

Measurement of synovial fluid and serum concentrations of the 846 epitope of chondroitin sulfate and of carboxy propeptides of type II procollagen for diagnosis of osteochondral fragmentation in horses

OBJECTIVE: To determine whether serum or synovial fluid concentrations of chondroitin sulfate epitope 846 and carboxy propeptides of type II collagen (CPII) can be used to diagnose osteochondral fragmentation (OC) in horses. ANIMALS: 38 horses with unilateral OC of the radiocarpal (n = 31) or intercarpal (33) joints and 8 clinically and radiographically normal horses. Procedures-For horses with OC, serum and synovial fluid concentrations of epitope 846, CPII, and keratan sulfate (KS) were determined, along with synovial fluid WBC counts and total protein concentrations. Serum epitope 846, CPII, and KS concentrations were measured in control horses. RESULTS: Synovial fluid epitope 846 and total protein concentrations were significantly higher in the joints with OC than in unaffected joints, but CPII and KS concentrations and WBC counts were not. Synovial fluid total protein and 846 epitope concentrations were linearly related to grade of OC. Serum epitope 846 and CPII concentrations were significantly higher in horses with OC than in control horses. Discriminant analysis allowed 27 of 34 (79%) horses to be correctly classified as having or not having OC on the basis of serum epitope 846 and CPII concentrations. CONCLUSIONS: Results suggest that serum and synovial fluid concentrations of epitope 846 and CPII are associated with OC. Increases in concentrations of epitope 846 and CPII suggest that increased synthesis of cartilage aggrecan and type II procollagen may be associated with OC. CLINICAL RELEVANCE: Measurement of serum epitope 846 and CPII concentrations may be useful in the diagnosis of OC in horses.     

Synovial fluid pH, cytologic characteristics, and gentamicin concentration after intra-articular administration of the drug in an experimental model of infectious arthritis in horses

Chemical and cytologic effects and bactericidal activity of gentamicin in septic synovial fluid were evaluated in an experimental model of infectious arthritis in horses. Septic arthritis was induced by inoculation of approximately 7.5 X 10(6) colony-forming units of Escherichia coli into 1 antebrachiocarpal joint in each of 16 clinically normal adult horses. Clinical signs of septic arthritis were evident 24 hours after inoculation. Horses were allotted to 3 groups: group-1 horses (n = 5) each were given 150 mg of gentamicin (50 mg/ml; 3 ml) intra-articularly (IA); group-2 horses (n = 5) each were given 2.2 mg of gentamicin/kg of body weight, IV, every 6 hours; and group-3 horses (n = 6) each were given buffered gentamicin, consisting of 3 mEq of sodium bicarbonate (1 mEq/ml; 3 ml) and 150 mg of gentamicin (50 mg/ml; 3 ml), IA. Synovial fluid specimens were obtained at posttreatment hour (PTH) 0, 0.25, 1, 4, 8, 12, and 24 via an indwelling intra-articular catheter. Synovial fluid pH was evaluated at PTH 0, 0.25, and 24. Microbiologic culture and cytologic examination were performed on synovial fluid specimens obtained at PTH 0 and 24, and gentamicin concentration was measured in all synovial fluid specimens. At PTH 0, E coli was isolated from synovial fluid specimens obtained from all horses. Synovial fluid pH was lower (range, 7.08 to 7.16) and WBC count was higher (range, 88,000 to 227,200 cells/microliters) and predominantly neutrophilic (95 to 99%) at PTH 0 than before inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gentamicin concentrations in synovial fluid obtained from the tarsocrural joints of horses after implantation of gentamicin-impregnated collagen sponges

OBJECTIVE: To determine synovial fluid gentamicin concentrations and evaluate adverse effects on the synovial membrane and articular cartilage of tarsocrural joints after implantation of a gentamicin-impregnated collagen sponge. ANIMALS: 6 healthy adult mares. PROCEDURES: A purified bovine type I collagen sponge impregnated with 130 mg of gentamicin was implanted in the plantarolateral pouch of 1 tarsocrural joint of each horse, with the contralateral joint used as a sham-operated control joint. Gentamicin concentrations in synovial fluid and serum were determined for 120 hours after implantation by use of a fluorescence polarization immunoassay. Synovial membrane and cartilage specimens were collected 120 hours after implantation and evaluated histologically. RESULTS: Median peak synovial fluid gentamicin concentration of 168.9 microg/mL (range, 115.6 to 332 microg/mL) was achieved 3 hours after implantation. Synovial fluid gentamicin concentrations were < 4 microg/mL by 48 hours. Major histologic differences were not observed in the synovial membrane between control joints and joints implanted with gentamicin-impregnated sponges. Safranin-O fast green stain was not reduced in cartilage specimens obtained from treated joints, compared with those from control joints. CONCLUSIONS AND CLINICAL RELEVANCE: Implantation of a gentamicin-impregnated collagen sponge in the tarsocrural joint of horses resulted in rapid release of gentamicin, with peak concentrations > 20 times the minimum inhibitory concentration reported for common pathogens that infect horses. A rapid decrease in synovial fluid gentamicin concentrations was detected. The purified bovine type I collagen sponges did not elicit substantial inflammation in the synovial membrane or cause mechanical trauma to the articular cartilage.     

Effect of Repeated Arthrocentesis on Cytologic Analysis of Synovial Fluid in Dogs

Background: Serial arthrocentesis and synovial fluid examination can be used to monitor treatment efficacy in immune-mediated polyarthritis (IMPA), but whether this procedure induces inflammation that interferes with test result interpretation is unknown.
Objectives: The aim of this study was to determine the effect of repeated arthrocentesis on synovial fluid cytology in healthy dogs.
Animals: Nine healthy client-owned dogs.
Methods: Prospective study. Arthrocentesis was performed under sedation on 4 joints (both carpi, 1 tarsus, 1 stifle) on each dog every 3 weeks, a total of 4 times. Automated cell counts were done on stifle fluid, smears were made, and differential cell counts done on smears from all joints. Slides were evaluated microscopically for erythrocyte numbers, total nucleated cell count, differential cell count, and cell morphology. Data were analyzed by 2-way analysis of variance.
Results: A total of 144 synovial fluid samples were examined. Repeated arthrocentesis was not associated with increases in synovial fluid neutrophil numbers. Mild mononuclear inflammation was detected in 13 samples from 6 dogs.
Conclusions and Clinical Importance: Serial arthrocentesis at 3-week intervals can rarely be associated with mild mononuclear joint inflammation, but does not appear to induce neutrophilic inflammation, at least in healthy dogs, and can be useful to monitor treatment response in canine IMPA.     

The disposition and local effects of intra-articular morphine in normal ponies

Morphine (15 mg in 5 ml saline) was injected into the left, and 5 ml saline into the right, tarsocrural joint of 8 ponies. Venous blood samples were collected before and at 0.5, 1, 2, 6 and 24 h after the intra-articular morphine injection and analysed for morphine and its metabolites. Synovial fluid was sampled from both tarsocrural joints before and 24 h after injection. Synovial white blood cell and red blood cell counts, protein and hyaluronate concentrations were measured in all the samples; and the synovial fluid morphine concentration from the left tarsocrural joint was measured 24 h after the injection. The peak mean plasma morphine concentration (7.1 μg/l) was detected in samples taken 0.5 h after the intra-articular morphine injection, but neither morphine nor its metabolites were found in plasma 6 h or more post injection. Morphine was detected in the synovial fluid of each pony 24 h after the injection. The plasma morphine or morphine-6-glucuronide concentrations were lower than those likely to have any systemic effect. The synovial fluid white blood cell count and protein concentration were increased and hyaluronate concentration decreased in samples taken 24 h after the intra-articular morphine injection, compared to the pre-injection samples. No differences were found between morphine and saline injected joints. It was concluded that morphine did not irritate the joint more than saline.     

Comparison of various treatments for experimentally induced equine infectious arthritis

To evaluate the effects of 5 treatments on clinical responses, synovial fluid analysis, radiographic changes, bacteriologic culture results of the synovial fluid and synovial membrane, microscopic characteristics of the synovial membrane, and articular cartilage histochemistry, Staphylococcus aureus organisms (1.6 X 10(6) colony-forming units) were inoculated into the tarsocrural joints of 12 horses (n = 24 joints; 2 joints/horse). Each horse was given phenylbutazone (2 g) orally, every 24 hours, beginning 24 hours after inoculation. Two horses (ie, 4 joints) were not given other treatment (controls; group 1). All other horses (ie, 20 joints) were given a trimethoprim-sulfadiazine combination orally, once daily (30 mg/kg; 8 joints) or twice daily (30 mg/kg q 12 hr; 12 joints). Each of these 20 joints were assigned to 1 of 5 treatment groups (4 joints/group) in a balanced incomplete block design. Group 2 (4 joints) was given only the antibiotics once daily. Twelve joints were treated by through-and-through joint lavage on day 1 (group 3), days 1 and 3 (group 4), or days 1, 3, and 6 (group 5). Joints in group 6 had an arthrotomy performed on day 1, with subsequent lavage via an indwelling drain every 12 hours for 4 days. In groups 3 through 6, 1 joint in each group was treated with antibiotics once daily, and 3 joints were treated with antibiotics twice daily. All horses were clinically assessed each day. Complete blood count was performed on days 3, 6, 10, and 21. Before inoculation and on days 0, 1, 3, 6, 10, and 21, synovial fluid specimens were collected and analyzed for color, clarity, total protein concentration, WBC count, differential count, and mucin clot-forming ability. Synovial fluid specimens were cultured bacteriologically before inoculation and on days 0 and 21. Horses in group 1 (controls) were euthanatized before day 6. All other horses were euthanatized on day 21. Tarsocrural joints were opened and examined. Synovial membrane specimens were bacteriologically cultured. Synovial membrane specimens were examined histologically (hemotoxylin and eosin stain) and articular cartilage specimens were (safranin O fast green stain) evaluated histochemically. Synovial membrane specimens were histologically graded into 5 categories. Intensity of articular cartilage intercellular staining with safranin 0 was graded for superficial, outer intermediate, inner intermediate, and deep zones. Two-way analysis of variance was performed to evaluate differences among groups and across time for the determinants evaluated.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of gentamicin sulfate and sodium bicarbonate on the synovium of clinically normal equine antebrachiocarpal joints

The effect of gentamicin sulfate, unbuffered and buffered with sodium bicarbonate, on synovial fluid and membrane of clinically normal equine joints was evaluated. Thirty-six adult horses with clinically normal antebrachiocarpal joints were allotted to 6 treatment groups of 6 horses each. One antebrachiocarpal joint in each horse was chosen for treatment. Group-1 horses were given gentamicin (3 ml; 50 mg/ml); group-2 horses were given sodium bicarbonate (3 ml; 1 mEq/ml); group-3 horses were given gentamicin (3 ml; 50 mg/ml) and sodium bicarbonate (3 ml; 1 mEq/ml); group-4 horses were not treated; and horses of groups 5 and 6 were given polyionic physiologic solution (3 and 6 ml, respectively). Synovial fluid specimens were obtained from 5 horses of each group for cytologic analysis at postinjection hours (PIH) 0, 24, 72, and 192 and for pH determination at PIH 0, 0.25, 0.5, 1, 4, 8, 24, 72, and 192. The sixth horse of each group was euthanatized at PIH 24, and the synovial membrane of the treated and contralateral (nontreated) antebrachiocarpal joints was examined macroscopically and microscopically. After intra-articular gentamicin administration, the mean synovial fluid pH was lowest (5.98) at PIH 0.25, but by PIH 8, it was not significantly different from the control value (group-5 horses). When sodium bicarbonate was combined with gentamicin before intra-articular administration, the mean synovial fluid pH was lowest (7.07) at PIH 0.25, but by PIH 1, it was not significantly different from the control value (group-6 horses).(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of the effects of intra-articular injection of dimethylsulfoxide on normal equine articular tissues

To evaluate the effects of intra-articular injection of dimethylsulfoxide (DMSO) on normal equine articular structures, 7 adult horses with clinically normal carpi were allotted to 2 treatment groups (group A, n = 4; group B, n = 3). In each horse after collection of synovial fluid samples, the right antebrachial carpal and middle carpal joints were aseptically injected with 2 ml of a 40% solution of 90% medical grade DMSO in lactated Ringer solution, and the corresponding joints of the left forelimb (controls) were injected with 2 ml of lactated Ringer solution. In group-A horses, 2 ml of synovial fluid was obtained prior to injections of 40% DMSO at 24 hours and 72 hours, for a total of 3 injections. At necropsy, synovial fluid, synovial membrane, and articular cartilage specimens were obtained. Group-B horses were injected with 40% DMSO in the same sequence; however, the series was repeated following a 1-week interval. Clinical evaluation of these horses revealed no evidence of carpal inflammation associated with any injection in any group. Synovial fluid analysis of DMSO-injected and control joints revealed insignificant differences in leukocyte counts and total protein content. There was no evidence of cartilage degradation on gross, histologic, or histochemical evaluation of any of the joints. Intercellular matrix staining of the articular cartilage failed to reveal any observable difference in glycosaminoglycan content between injection with DMSO or lactated Ringer solution.     

Comparison of Synovial Fluid in Middle Carpal Joints Undergoing Needle Aspiration, Infusion with Saline, and Infusion with a Combination of N-Acetyl-d-Glucosamine, Hyaluronic Acid, and Sodium Chondroitin Sulfate

Synovial fluid white blood cell (WBC) count and total protein (TP) concentration were evaluated in the midcarpal joints of horses to not only determine the effects of needle aspiration, infusion with saline, and infusion with a combination of N-acetyl-d-glucosamine, hyaluronan, and sodium chondroitin sulfate (GHCS) at two different doses to evaluate the latter for safety, but to also provide information on saline injection as a control in joints. The midcarpal joints from 24 horses were used for this study. One midcarpal joint served as an untreated control, in which only synovial fluid was aspirated, whereas the opposite joint received either 2.5 mL isotonic saline (n = 8 horses), 2.5 mL of GHCS (n = 8 horses), or 7.5 mL of GHCS (n = 8 horses). Synovial fluid WBC and TP concentration were measured on days 1, 3, 5, 7, 14, and 21. Needle aspiration caused a transient increase in synovial fluid WBC and TP levels after 1 day. Instillation of fluid (2.5 mL), whether saline or GHCS, caused significantly higher WBC and TP concentrations. GHCS at a dose of 7.5 mL created an elevation in TP level for an additional 48 hours; however, after 48 hours, WBC and TP were at concentrations that were not statistically different from controls. Even though an increase in WBC and TP concentrations occurred because of intra-articular saline and GHCS administration, these results were transient demonstrating that GHCS is no different than saline on synovial fluid, WBC, and TP parameters and that as previously described short-term elevation in synovial fluid inflammatory parameters should be expected when saline is used as a control.     

Intra-articular tissue response to analytical grade metrizamide in dogs

The effect of analytical grade metrizamide (AM) injected into the canine stifle, for purposes of arthrography, was studied in 12 adult dogs using saline solution as the control solution injected into the contralateral joints. The AM was used at a concentration of 280 mg of iodine/ml and was administered at the dose of 0.3 ml/cm thickness of the stifle joint. For each joint, arthrocentesis was done before and 7 days after injection of either the contrast medium or saline solution. Physical, biochemical, and cytologic examinations were done on the synovial fluid while the synovial membranes and femoral articular cartilages were sectioned, stained, and examined for histopathologic changes. At the 95% confidence level, significant differences in the total and differential mononuclear cell counts were not seen between the AM- and saline solution-injected joints. However, some subtle changes in the synovial membranes were observed. Intra-articular injection of AM or saline solution initiated a mild inflammatory response, the AM causing slightly more response than the saline solution.     

Continuous infusion of gentamicin into the tarsocrural joint of horses

OBJECTIVE: To develop a method for continuous infusion of gentamicin into the tarsocrural joint of horses, to determine pharmacokinetics of gentamicin in synovial fluid of the tarsocrural joint during continuous infusion, and to evaluate effects of continuous infusion of gentamicin on characteristics of the synovial fluid. ANIMALS: 12 healthy adult horses. PROCEDURE: An infusion catheter consisting of flow control tubing connected to a balloon infuser was used. Gentamicin solution (100 mg/ml) was infused in the right tarsocrural joint and balanced electrolyte solution was infused in the left tarsocrural joint for 5 days. Synovial fluid and serum gentamicin concentrations were measured by use of a fluorescence polarization immunoassay. RESULTS: 17 of the 24 (71%) infusion catheters initially placed functioned without complications for the entire 5-day infusion period. Median gentamicin concentration in synovial fluid from treated joints during the 5-day infusion period ranged from 2875 to 982 microg/ml. Median serum gentamicin concentration during this period ranged from 2.31 to 2.59 microg/ml. Mean (+/- SD) elimination half-life and total clearance of gentamicin from the synovial fluid were 6.25+/-1.01 hours and 1.52+/-0.96 ml/min, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: An infusion catheter can be used for continuous infusion of gentamicin into the tarsocrural joints of horses for up to 5 days. At a gentamicin dosage of 0.17+/-0.02 mg/kg/h, continuous intra-articular infusion results in synovial fluid gentamicin concentrations greater than 100 times the minimal inhibitory concentration reported for common equine pathogens.     

Regional limb perfusion for antibiotic treatment of experimentally induced septic arthritis.

Septic arthritis was induced in one antebrachiocarpal joint of seven horses by the intra-articular injection of 1 mL Staphylococcus aureus suspension containing a mean of 10(5) colony-forming units. Twenty-four hours after inoculation, four horses were treated by regional perfusion with 1 g of gentamicin sulfate, and three horses received 2.2 mg/kg gentamicin sulfate intravenously (IV) every 6 hours. Synovial fluid was collected for culture and cytology at regular intervals, and the synovial membranes were collected for culture and histologic examination at euthanasia 24 hours after the first treatment. Gentamicin concentration in the septic synovial fluid after three successful perfusions was 221.2 +/- 71.4 (SD) micrograms/mL; after gentamicin IV, it was 7.6 +/- 1.6 (SD) micrograms/mL. The mean leukocyte count in the inoculated joints decreased significantly by hour 24 in the successfully perfused joints. Terminal bacterial cultures of synovial fluid and synovial membranes were negative in two horses with successfully perfused joints. S. aureus was isolated from the infected joints in all three horses treated with gentamicin IV.     

Autologous processed plasma: cytokine profile and effects upon injection into healthy equine joints

This experimental controlled study was performed to evaluate the composition of autologous processed plasma (APP), and the effects of APP intra-articular injection into healthy equine metacarpophalangeal joints. The effects on joints were analysed with a short-phase protocol and a prolonged-phase protocol using saline-injected joints as controls. For the short protocol, horses received one intra-articular APP injection. Synovial fluid samples were collected prior to the injection and 3, 6, 24, 48, and 16 h after treatment. For the prolonged protocol, the joints received three weekly injections of APP, and samples were collected at 0, 7, 14, 21, and 28 days before APP administration. IL1-ra level was found to be increased in APP compared to plasma. Upon intra-articular administration of APP, transient (up to 24 h) increases in white blood cell (WBC) counts along with elevated protein and prostaglandin E₂ (PGE₂) concentrations were observed in the treated joints. Over the 28-day observation period, APP did not elicit changes relative to baseline levels, but WBC counts, PGE₂ and chondroitin sulphate concentrations were lower than those found in the control. In conclusion, APP intra-articular injection induced a mild and transitory inflammatory response but no inflammation reaction was observed over a longer period of treatment and observation.     

Effects of 0.05% Chlorhexidine Lavage on the Tarsocrural Joints of Horses

In six horses, a 0.05% solution of chlorhexidine diacetate was used to lavage one tarsocrural joint; the contralateral control joint was lavaged with lactated Ringer's solution. Horses were evaluated daily for lameness. Synovial fluid samples were collected on days 1, 4, and 8 for determination of protein concentration, total and differential leukocyte counts, and mucin clot formation. After death on day 8, synovium and osteochondral samples were collected from the tarsocrural joints for examination of morphology and proteoglycan staining. Lavage with chlorhexidine solution caused lameness that was reduced but still evident at day 8. Synovial protein concentration was significantly increased by chlorhexidine lavage; the greatest increase occurred on day 1. Joint lavage increased synovial leukocyte counts on day 1, primarily by increasing polymorphonuclear (PMN) cell counts. Although total synovial leukocyte counts returned to normal by day 4, PMN cell counts remained elevated through day 8; PMN cell counts for chlorhexidine-lavaged joints were typically twice that of control joints. Chlorhexidine lavage caused synovial ulceration, inflammation, and abundant fibrin accumulation. Consistent differences in proteoglycan staining were not detected between control and chlorhexidine-lavaged joints. Joint lavage with 0.05% chlorhexidine diacetate, the lowest known bactericidal concentration, is not recommended for equine joints.