Biomedical subjects

J P Caron

Publications and source records attributed to J P Caron.

At least 19 recordsLinked to original sources

PubMed1999

Factors influencing recovery from and duration of lameness in Michigan (USA) horses.

The objective of this study was to identify factors that may affect recovery from and duration of a case of lameness in a stratified random sample of Michigan horses. This was done using data from Phase-II of the Michigan equine monitoring system (MEMS Phase-II), the equine health-monitoring study [Kaneene et al., Prev. Vet. Med. 29 (1997b) 277-292; Ross and Kaneene, Prev. Vet. Med. 28 (1996a) 209-224; Ross and Kaneene, Prev. Vet. Med. 29 (1996b) 59-75; Ross et al., Am. J. Vet. Res. 59 (1997) 23-29]. In this study, statistical modelling was conducted to evaluate risk factors affecting recovery from and duration of lameness using multivariable logistic regression and Cox's proportional hazards regression, respectively. Of 357 incident lameness cases reported during MEMS Phase-II, 280 (78.6%) were reported to have recovered. The median duration of a lameness case was 18 days (1st quartile (Q): 1, maximum (Max): 360). A total of 296 of 357 (82.9%) incident lameness cases received some type of treatment. Of 619 total treatments used, 329 (53.2%) were administered, conducted or applied by a veterinarian. Horses experiencing other types of lameness were less likely to recover than those experiencing hoof lameness (odds ratio (OR) = 0.48; 95% CI: 0.25, 0.93). Horses that had participated in exercise-related activities during the study period and prior to the lameness were more likely to recover (OR = 1.91; 95% CI: 1.05, 3.50). Treatment of the lameness was associated with an increased likelihood of recovery (OR = 1.82; 95% CI: 0.97, 3.45). Cases with a veterinarian involved in the diagnosis were associated with a decreased risk of recovery (OR = 0.48; 95% CI: 0.27, 0.84) and a longer duration lameness (HR = 0.58; 95% CI: 0.45, 0.73)--which might indicate that these cases were more complex or severe. Although cases treated for lameness were more likely to recover (OR = 1.82; 95% CI: 1.05, 3.50), treatment was not associated with lameness duration (HR = 0.58; 95% CI: 0.45, 0.73).

Animals↗

PubMed1999

Methicillin-resistant Staphylococcus aureus outbreak in a veterinary teaching hospital: potential human-to-animal transmission.

During a 13-month period, 11 equine patients visiting a veterinary teaching hospital for various diagnostic and surgical procedures developed postprocedural infections from which methicillin (oxacillin)-resistant Staphylococcus aureus (MRSA) strains were isolated. The S. aureus isolates were identified by conventional methods that included Gram staining, tests for colonial morphology, tests for clumping factor, and tests for coagulase and urease activities and were also tested with the API STAPH IDENT system. Antimicrobial susceptibility tests were performed by the disk diffusion method. The biochemical profile and antibiogram of each isolate suggested that the isolates may have come from a common source. Because MRSA strains are very uncommon animal isolates but are rather common human isolates, a nasal swab specimen for culture was collected voluntarily from five persons associated with equine surgery and recovery in an attempt to identify a possible source of the organisms. MRSA strains were isolated from three of the five people, with one person found to be colonized with two biotypes of MRSA. The MRSA isolates from the people appeared to be identical to the isolates from horses. Further study of the isolates included SmaI and EagI macrorestriction analysis by pulsed-field gel electrophoresis conducted in two different laboratories. The results indicated that both the equine and human isolates were members of a very closely related group which appear to have originated from a common source. On the basis of the pattern associated with the infection, it is speculated that the members of the Veterinary Teaching Hospital staff were the primary source of the infection, although the specific mode of transmission is unclear.

Animals↗

PubMed1999

Effect of longeing and glucosamine supplementation on serum markers of bone and joint metabolism in yearling quarter horses.

The effect of longeing and glucosamine supplementation on known biological markers of joint disease was studied in yearling quarter horses. Twenty-one yearling quarter horses were randomly assigned to one of 4 treatments: 1) longeing (longeing 20 min daily) supplement control (LN); 2) longeing/glucosamine (LG); 3) walking (mechanical walker for 120 min daily (WN)); and 4) walking/glucosamine (WG). Oral glucosamine was administered at 5.5 g b.i.d. weeks 1-4, 3.5 g b.i.d. during weeks 5-6, and 2.0 g b.i.d. during weeks 7-8. Serum was obtained weekly for 8 wk and analyzed for keratan sulfate and osteocalcin concentrations. Walked horses receiving glucosamine showed slight elevation in serum keratan sulfate compared to controls (P = 0.04). Glucosamine or longeing exercise had no significant effect (6 > or = 0.08) on serum osteocalcin concentrations. Under these conditions, longeing and/or glucosamine supplementation did not significantly alter serum concentrations of keratan sulfate or osteocalcin.

Animals↗

PubMed1998

Influence of exogenous hyaluronan on synthesis of hyaluronan and collagenase by equine synoviocytes.

OBJECTIVE: To evaluate the influence of exogenous hyaluronan (HA) on in vitro synthesis of HA and collagenase by equine synoviocytes from normal and inflamed joints. ANIMALS: 9 adult horses. PROCEDURE: Synoviocytes for culture were taken from the middle carpal joint of 3 horses with normal joints (control) and 6 horses with osteochondral fractures (principal). Synoviocytes were propagated in monolayer cultures and were incubated with 3 commercial HA products at concentrations of 0, 200, 400, and 1,500 micrograms/ml. Newly synthesized HA was radiolabeled with [3H]glucosamine and quantified by cetylpyridinium chloride precipitation and liquid scintillation counting. The hydrodynamic size of radioactive HA was determined by high-performance liquid chromatography, and collagenase activity was evaluated by use of a quantitative radioactive collagen film assay. RESULTS: Exogenous HA influenced neither the rate of synthesis nor the hydrodynamic size of the newly produced HA by control or principal cell cultures. Culture supernatants from abnormal synovium, exposed to 400 and 1,500 micrograms of exogenous HA/ml, contained significantly more collagenase activity than did those exposed to lower concentrations. CONCLUSION: Although HA is thought to have beneficial effects in equine arthropathies, the principal mechanisms of action of HA do not appear to be stimulation of synthesis of HA of augmented molecular weight or marked inhibition of collagenase synthesis.

Animals↗

PubMed1998

Osteochondritis dessicans and subchondral cystic lesions in draft horses: a retrospective study.

The clinical features, radiographic findings, treatment, and outcome in 51 draft horses with osteochondritis dessicans (OCD) or subchondral cystic lesions (SC) are reported. Clydesdale and Percheron were the most commonly affected breeds, and affected animals represented only 5% of the hospital population of draft horses. Horses were most frequently affected in the tibiotarsal joints and 73% (24 of 33 cases) of the horses with tibiotarsal effusion were affected bilaterally. Osteochondritis dessicans of the distal intermediate ridge was the most common lesion found in the tibiotarsal joint. The stifle was also frequently affected; 87% (13 of 15 cases) of horses with femoropatellar OCD only were lame, and lesions were most commonly located on the lateral trochlear ridge. Sixteen cases were managed conservatively, 30 received surgery, and 5 were euthanized. Lameness, effusion, or both clinical signs resolved in more than 50% of surgically treated cases, but clinical signs improved in 30% of conservatively-managed cases.

Animals↗

PubMed1997

Effects of tenidap on the progression of osteoarthritic lesions in a canine experimental model. Suppression of metalloprotease and interleukin-1 activity.

OBJECTIVE: To study, in vivo, the therapeutic effectiveness of tenidap, an antirheumatic drug, on the progression of lesions in an experimental osteoarthritis (OA) dog model. The action of tenidap on the activity and expression of metalloproteases in cartilage, as well as on the bioactivity of interleukin-1 (IL-1) in synovial fluid, was determined. METHODS: The anterior cruciate ligament of the right stifle joint of 20 mongrel dogs was sectioned through a stab wound. Dogs were divided into 3 groups: group I (n = 7) received no treatment, group II (n = 6) was treated with oral omeprazole (20 mg/day), and group III (n = 7) received oral omeprazole (20 mg/day) and a therapeutic dosage of oral tenidap (3 mg/kg twice daily). Four weeks following surgery, the untreated dogs (group I) were killed, and drug treatments were begun for the other dogs (groups II and III). These dogs received medications for 8 weeks (weeks 4-12) and then were killed. Evaluations were made of the incidence and size of osteophytes as well as of the size and grade of cartilage erosions on both the condyles and plateaus. Histologic examination of the severity of the cartilage lesions and synovial inflammation was also performed. Activity levels of collagenase, stromelysin, and gelatinase as well as collagenase-1, collagenase-3, and stromelysin-1 messenger RNA were determined in the cartilage. The level of IL-1 activity in the synovial fluid was also measured. RESULTS: Among the dogs with OA, lesions were more severe at 12 weeks than at 4 weeks. Group III (tenidap-treated) dogs had a slightly reduced incidence of osteophytes compared with the group II (12-week OA) dogs (71% versus 100%), and the size of the osteophytes was significantly diminished (mean +/- SEM 1.75 +/- 0.69 mm versus 4.38 +/- 0.64 mm). Macroscopically, tenidap decreased the size (condyles 6.00 +/- 2.18 mm2 versus 21.08 +/- 6.70 mm2, plateaus 15.50 +/- 4.77 mm2 versus 35.0 +/- 3.64 mm2) and the grade (condyles 0.57 +/- 0.20 versus 1.17 +/- 0.21, plateaus 1.07 +/- 0.22 versus 2.00 +/- 0.25) of the cartilage lesions compared with the 12-week OA dogs. At the histologic level, the severity of cartilage lesions was also decreased in the tenidap-treated dogs versus the 12-week OA dogs, both on the condyles (3.43 +/- 0.54 versus 5.55 +/- 0.38) and on the plateaus (3.39 +/- 0.35 versus 5.54 +/- 0.60). All 3 OA groups showed a significant and similar level of synovial inflammation. Tenidap markedly decreased collagenase, stromelysin, and gelatinase activity, as well as the level of expression of collagenase-3 in the cartilage. Interestingly, the activity level of IL-1 in synovial fluid was also significantly reduced in the tenidap-treated dogs. CONCLUSION: Tenidap markedly reduced the severity of OA lesions, indicating the effect of this drug in decreasing the progression of disease. It appears that the drug acts by reducing the activity and/or expression of metalloproteases in cartilage, a process known to play a major role in the pathophysiology of OA lesions. This effect could be mediated by the suppressive effect of tenidap on IL-1 activity.

Animals↗

PubMed1997

In vivo suppression of early experimental osteoarthritis by interleukin-1 receptor antagonist using gene therapy.

OBJECTIVE: This study explored the therapeutic effect of interleukin-1 receptor antagonist (IL-1Ra), administered by gene transfer, on the progression of osteoarthritic (OA) lesions in an experimental dog model. METHODS: Seventeen mature mongrel dogs were divided into 3 groups. Group 1 (n = 7) had an anterior cruciate ligament (ACL) section of the right knee through a stab wound incision. Groups 2 and 3 (n = 5 per group), had an ACL section of the right knee and partial synovectomy of the left knee. Each dog's synovium was subjected to enzymatic digestion, and the synovial fibroblasts were propagated in monolayer culture. Synovial cells from each dog were transduced in vitro using the retrovirus MFG with either the Escherichia coli beta-galactosidase (lac Z) gene (group 2) or the human IL-1Ra gene (group 3). Two days after surgery, the dogs received intraarticular injections as follows: group 1 phosphate buffered saline (PBS) (2 ml); group 2 autologous cells (60 x 10(6) cells/2 ml of PBS) transduced with the lac Z gene; group 3 autologous cells transduced with the IL-1Ra gene. Synovial fluid was aspirated at 2 weeks and 4 weeks. All dogs were euthanized at 4 weeks postsurgery. The right knees were dissected, and lesions were scored for macroscopic and microscopic changes. Synovial explants were dissected and representative specimens were used for histology or were cultured for 48 hours. The levels of IL-1Ra in synovial fluid and synovial explant conditioned medium were measured by specific enzyme-linked immunosorbent assay. RESULTS: The level of IL-1Ra in synovial fluid of group 3 was 202.8 +/- 131.5 ng/ml (mean +/- SEM) at 2 weeks and 2.8 +/- 2.2 ng/ml at 4 weeks after surgery. Membrane explants isolated from dogs that received synovial cells transduced with the IL-1Ra gene (group 3) actively produced IL-1Ra (4.0 +/- 2.0 ng/gm of tissue wet weight). The severity of OA cartilage lesions was similar in groups 1 and 2. In contrast, group 3 dogs had a marked reduction in macroscopic lesion severity on the tibial plateaus (P < 0.01 for grade; P < 0.04 for size) and femoral condyles. Moreover, the histologic lesion severity was decreased on both plateaus (P < 0.06) and condyles. CONCLUSION: This study showed that a local increase in IL-1Ra production in OA knee joints by intraarticular injection of transduced synovial cells can reduce the progression of experimentally induced lesions.

Animals↗

PubMed1997

The therapeutic effects of tenidap in canine experimental osteoarthritis: relationship with biochemical markers.

OBJECTIVE: To define the dose-response relationship of the therapeutic effects of tenidap in experimental osteoarthritis (OA) and relate this to the effects on interleukin 1 (IL-1) and metalloprotease activity. METHODS: The anterior cruciate ligament of the right knee joints of 22 mongrel dogs were sectioned (ACLS) through a stab wound. Seven dogs received no treatment, 5 were treated with oral omeprazole (20 mg/day), another 5 were treated with oral tenidap (1.5 mg/kg bid) plus omeprazole (20 mg/day), and 5 received tenidap (0.5 mg/kg bid) plus omeprazole (20 mg/day). The dogs received medication for 8 weeks beginning 4 weeks after surgery. All dogs were killed 12 weeks after surgery, except for those in the first group, which were sacrificed at 4 weeks. Lesions were evaluated macroscopically for the incidence and size of osteophytes and the area and grade of cartilage erosions on the condyles and plateaus, along with histologic evaluation of the severity of the cartilage lesions and synovial inflammation. Stromelysin, collagenase, and gelatinase activities were measured in cartilage and synovial membrane. Also, the level of IL-1 activity was measured in the synovial fluid. RESULTS: Dogs treated with tenidap at both 1.5 and 0.5 mg/kg bid exhibited a reduction in the size of osteophytes (2.25 +/- 0.30 mm, 1.70 +/- 0.65 mm, respectively) compared to the 12 weeks OA group (3.55 +/- 0.94 mm). Tenidap also significantly decreased the size and/or grade or cartilage macroscopic lesions on both condyles and plateaus. This reduction was more pronounced in dogs treated with the higher drug dose. The histological severity of cartilage lesions on femoral condyles was reduced for both tenidap doses used and significance (p < 0.04) reached for the 1.5 mg/kg bid tenidap treated dogs. Tenidap markedly and significantly reduced the level of metalloprotease activity for all 3 enzymes tested in synovial membrane (stromelysin, p < 0.03; collagenase, p < 0.02; gelatinase, p < 0.03) and in cartilage (stromelysin, p < 0.02; collagenase, p < 0.02; gelatinase, p < 0.03) with greater reduction, in general, in dogs treated with the higher dose of tenidap. IL-1 activity was significantly reduced (p < 0.02) only in animals treated with tenidap at 1.5 mg/kg bid. CONCLUSION: This study confirms that tenidap is an effective anti-osteoarthritic drug in this ACLS model where therapy was begun 4 weeks after surgery. We have defined doses that gave graded therapeutic effects, and under these conditions the effectiveness coincided with the suppression of IL-1 and metalloprotease activity, processes known to play a major role in the pathophysiology of OA lesions.

Animals↗

PubMed1996

Results of a survey of equine practitioners on the use and perceived efficacy of polysulfated glycosaminoglycan.

OBJECTIVE: To determine the patterns of use and perceived efficacy of polysulfated glycosaminoglycan (PSGAG) for the treatment of degenerative joint disease in horses. DESIGN: Cross-sectional mail survey. SAMPLE POPULATION: 1,522 equine practitioners. PROCEDURE: Information was obtained on frequency and route of administration of PSGAG for the treatment of each of 4 forms of degenerative joint disease, the efficacy of PSGAG, and its efficacy compared with that of sodium hyaluronate. Data were analyzed by nonparametric and multivariate regression methods. RESULTS: Response rate was 40.5%. Of practitioners responding, 26% were classified as having a special interest in lameness and 74% as general practitioners. Use of PSGAG was reported by 90.5% of all practitioners, but lameness practitioners used PSGAG more frequently than general practitioners. Use of PSGAG also was significantly more common among practitioners involved predominately with racing. Thoroughbreds, Standardbreds, or show horses. Use of PSGAG was reported to be moderately effective in the treatment of the 4 joint disease conditions. Practitioners treating Thoroughbred racehorses gave highest efficacy scores, and pleasure horse practitioners gave lowest efficacy scores. Use of PSGAG was considered more effective than sodium hyaluronate for the treatment of subacute degenerative joint disease and less effective for idiopathic joint effusion and acute synovitis. CLINICAL IMPLICATIONS: Use of PSGAG is regarded as moderately effective overall and is considered most useful in the treatment of subacute degenerative joint disease. The efficacy of PSGAG for incipient and chronic forms of degenerative disease is considered comparable to that of sodium hyaluronate.

Animals↗

PubMed1996

Chondroprotective effect of intraarticular injections of interleukin-1 receptor antagonist in experimental osteoarthritis. Suppression of collagenase-1 expression.

OBJECTIVE: To investigate the in vivo effect of recombinant human interleukin-1 receptor antagonist (rHuIL-1Ra) on the development of lesions and the expression of metalloproteases in the canine experimental osteoarthritis (OA) model. METHODS: The right anterior cruciate ligament was sectioned percutaneously in 3 groups of dogs. The control group (n = 5) received an intraarticular injection of sterile physiologic saline (1 ml) twice weekly for 4 weeks starting on the day of surgery. The remaining 2 groups received intraarticular injections of either 2 mg (n = 6) or 4 mg (n = 5) rHuIL-1Ra in 1 ml of physiologic saline according to the same schedule as the first group. All dogs were killed 4 weeks after surgery. The macroscopic appearance of femoral condyle osteophytes and the size and severity of cartilage lesions on femoral condyles and tibial plateaus were evaluated, as were the histologic features of cartilage and synovial membrane. Levels of collagenase-1 and stromelysin-1 messenger RNA expression in cartilage and synovium were determined by Northern blotting. RESULTS: Recombinant human IL-1Ra exerted a dose-dependent protective effect on the development of osteophytes and cartilage lesions in vivo. Treatment with rHuIL-1Ra reduced the incidence (saline-treated group 70%, 2 mg rHuIL-1Ra-treated group 42%, 4 mg rHuIL-1Ra-treated group 20%) and size (saline-treated group 2.3 +/- 0.7 mm [mean +/- SEM], 2 mg rHuIL-1Ra-treated group 0.7 +/- 0.3 mm, 4 mg rHuIL-1Ra-treated group 0.5 +/- 0.3 mm) of femoral condyle osteophytes. In addition, a dose-dependent decrease in the size (saline-treated group 24.40 +/- 8.17 mm2, 2 mg rHuIL-1Ra-treated group 20.90 +/- 8.01 mm2, 4 mg rHuIL-1Ra-treated group 7.70 +/- 5.16 mm2) and the grade (0-4 scale; saline-treated group 1.20 +/- 0.29, 2 mg rHuIL-1Ra-treated group 1.00 +/- 0.26, 4 mg rHuIL-1Ra-treated group 0.30 +/- 0.21) of the tibial plateau cartilage lesions was found, with a significant difference (P < 0.04) reached only with 4 mg rHuIL-1Ra. Similarly, the histologic lesions in dogs treated with 4 mg rHuIL-1Ra (Mankin scale; mean +/- SEM 2.95 +/- 0.53) were significantly less severe (P < 0.002) compared with those in the saline-treated group (4.95 +/- 0.54). Importantly, rHuIL-1Ra treatment led to a significant reduction (P < 0.005) of collagenase-1 expression in OA cartilage. CONCLUSION: This study demonstrated that intraarticular injections of rHuIL-1Ra can protect against the development of experimentally induced OA lesions. This effect could result, at least in part, from a reduction of collagenase-1 expression. However, other catabolic processes involved in the degradation of OA cartilage may also be affected.

Animals↗

PubMed1996

Apparent viscosity of the synovial fluid from mid-carpal, tibiotarsal, and distal interphalangeal joints of horses.

OBJECTIVE: To compare the apparent viscosity of normal synovial fluid of the mid-carpal, tibiotarsal, and interphalangeal joints of horses. DESIGN: Viscosity evaluation over a range of shear rates was used to characterize the apparent viscosity of synovial fluids from the 3 joints. ANIMALS: 60 clinically normal adult horses. PROCEDURE: Viscosity data for synovial fluid samples were obtained over a shear rate range of 10 to 250/s and apparent viscosity was calculated at 50, 100, 150, 200, and 250/s. Effect of shear rate on apparent viscosity was determined, using a two-way ANOVA, with significant differences tested, using a Tukey's test at a significance level of P < 0.05. RESULTS: Synovial fluid from all these joints indicated shear thinning behavior: decreased apparent viscosity with increased shear rate. Apparent viscosity of synovial fluid from the 3 joints was not significantly different over the shear rate range of 50 to 250/s. CONCLUSION: Results of this study indicate that the apparent viscosity of the distal interphalangeal joint is not less than that of other joints, as has been reported. CLINICAL RELEVANCE: The observation of decreased synovial fluid viscosity of distal interphalangeal joint fluid should be considered as suggestive of joint disease.

Analysis of Variance↗

PubMed1996

Modulation of matrix metalloprotease 13 (collagenase 3) gene expression in equine chondrocytes by interleukin 1 and corticosteroids.

OBJECTIVE: To determine whether matrix metalloprotease 13 (MMP-13; collagenase 3) is produced by equine chondrocytes and to investigate modulation of its expression by recombinant human interleukin 1 beta (rhIL-1 beta) and corticosteroids. PROCEDURE: Equine chondrocytes in monolayer culture were stimulated with rhIL-1 beta. Total RNA was extracted, purified, and reverse transcribed into DNA. Using appropriate primers, a putative MMP-13 fragment was amplified by polymerase chain reaction, and cloned into a bacterial vector. The resultant fragment was purified and sequenced, then was used to prepare a digoxigenin-labeled cRNA probe. Monolayer cultures of first-passage chondrocytes were treated with rhIL-1 beta in the presence or absence of dexamethasone (10(-6)M) or methylprednisolone acetate (10(-9)M to 10(-5)M), in addition to positive and negative controls. Cellular RNA was extracted and resolved on agarose gels and subjected to northern blot analysis, using the equine MMP-13 probe. RESULTS: Reverse transcriptase-polymerase chain reaction enabled isolation of a 0.6-kb fragment of equine MMP-13 cDNA that had 93% homology with the human MMP-13 cDNA sequence. rhIL-1 significantly stimulated MMP-13 expression in the chondrocytes. Methylprednisolone acetate inhibited the stimulatory effects of rhIL-1 in dose-dependent manner that was statistically significant at 10(-5)M. CONCLUSIONS: Novel information was gained on the existence of MMP-13 and its expression in equine chondrocytes, which suggests a possible role for this enzyme in matrix degradation in horses with arthritis.

Animals↗

PubMed1994

Surgical treatment for epiglottic entrapment in horses: 51 cases (1981-1992).

Medical records of 51 horses with epiglottic entrapment were reviewed, and the outcome after surgical treatment was evaluated by use of results from a survey of owners and from race records. Horses with epiglottic entrapment and no additional problem (uncomplicated) of the nares, nasal passages, pharynx, or larynx (upper airway) that were treated by transoral axial division (group 1) or resection via laryngotomy (group 2), and horses with epiglottic entrapment complicated by an additional upper airway abnormality (group 3) were compared. The cost of treatment, duration of hospitalization, time to first race start after surgery, and complication rate were significantly (P < 0.05) less in horses in group 1, compared with those in horses of group 2. Owner survey indicated that a significantly greater percentage (82%) of horses in group 1 had a successful outcome after transoral axial division, compared with that (27%) of horses in group 2. Analysis of race records indicated that performance was similar between horses in groups 1 and 2, and significantly more horses with an additional upper airway lesion (group 3) failed to return to racing than did horses with uncomplicated epiglottic entrapment (groups 1 and 2). Transoral axial division of the ary-epiglottic fold is recommended as an appropriate treatment for uncomplicated epiglottic entrapment. Resection via laryngotomy should be reserved for treatment of epiglottic entrapment associated with excessively thick and scarred aryepiglottic folds and for intermittent epiglottic entrapment in horses for which surgical correction is deemed appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

A silver-impregnation and immunocytochemical study of innervation of the distal sesamoid bone and its suspensory ligaments in the horse.

The innervation of the navicular bone (os sesamoideum distale) and its suspensory ligaments (ligamenta sesamoidea collateralia) (CSL) or proximal suspensory ligament and the ligamentum sesamoideum distale impar or the distal sesamoidean impar ligament (DS-impar ligament) was examined using combined anatomical techniques of silver impregnation and immunocytochemistry. Silver impregnation studies revealed an abundance of nerve fibres present in both the CSL and DS-impar ligament with the latter having relatively more nerve fibres. These silver-impregnated nerves coursed parallel to and were associated with the vasculature rather than appearing to innervate the vessels. Immunocytochemistry identified several sensory-related neuropeptides (calcitonin gene-related peptide (CGRP), substance P (SP) and neurokinin A (NKA)) in the nerves of the navicular bone and suspensory ligaments. More peptidergic nerves were evident within the synovial membrane and loose connective tissue in the dorsal part than in the palmar aspect of the CSL. In the CSL along the synovial membrane bordering the distal interphalangeal joint, the CGRP, SP and NKA were present in the nerves of vessels as well as the intimal layer of the distal interphalangeal joint. In the DS-impar ligament, there were many more nerves innervating vessels and the synovial membrane between the navicular bone and the third phalanx than were present in these structures in the CSL. Nerves with all 3 peptides entered the navicular bone via the proximal border and the distal groove to innervate the perichondrium, trabeculae and osteons. SP-like nerves also innervated the cortical bone underlying the articular cartilage. We suggest that these sensory nerve peptides contribute to the pathology of the navicular syndrome. The distribution of the nerves in the CSL and the DS-impar ligament could explain the clinical effects of local anaesthetics injected into the distal interphalangeal joint.

Animals↗

PubMed1993

Substance P innervation of equine synovial membranes: joint differences and neural and nonneural receptor localizations.

Substance P (SP) immunocytochemistry and receptor autoradiography were used to define the innervation of the equine synovial membrane of joints equivalent to the wrist and knuckle of man. SP-immunoreactive fibers were mainly concentrated around blood vessels in the subsynovial layer, although not exclusively, while in the more distal joint, SP fibers were more frequently seen in the synovial surface layer. Iodinated SP receptor autoradiography studies revealed silver grain concentrations in the advential layer of blood vessels associated with the vasa vasorum, on the vascular endothelium and in the synovial surface. These findings suggest that SP has various sites of action within the synovial membrane, each of which may contribute both a sensory function and a different component of the inflammatory process to the joint.

Animals↗

PubMed1993

Immunocytochemical and dye distribution studies of nerves potentially desensitized by injections into the distal interphalangeal joint or the navicular bursa of horses.

To determine whether the distal interphalangeal (DIP) joint directly or indirectly communicates with the navicular bursa (bursa podotrochlearis) and to identify sensory nerves in these synovial structures that might be desensitized by intra-articular injections of anesthetics, Evans blue dye in physiologic saline solution, Luxol fast blue dye with mepivicaine, or commercial latex was injected into the DIP joint (5 ml) or the navicular bursa (3 ml) of 152 digits obtained from horses or ponies at necropsy. The digits were frozen, cut with a band saw, and examined for distribution of dye or latex. Of 122 digits that had injections into the DIP joint, 120 did not have evidence of a communication between the DIP joint and either the navicular bursa or digital flexor tendon sheath. Of 16 digits that had injections into the navicular bursa, 14 did not have evidence of a direct communication with the DIP joint. Injection of dye into the DIP joint resulted in diffusion of dye and staining of other structures, including the synovial linings of the collateral sesamoidean ligaments and of the distal sesamoidean impar ligament and the medullary cavity of the navicular bone. In addition, a blue tinge was observed in the navicular bursa after dye was injected into the DIP joint, suggesting an indirect, and potentially functional, communication between the DIP joint and the navicular bursa. Injection of dye into the navicular bursa resulted in staining only of the bursa's synovial lining. Immunocytochemical analysis revealed nerves immunoreactive for the peptidergic neurotransmitters substance P, and calcitonin gene-related peptide located in structures that were stained after dye was injected into the DIP joint.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Local↗

PubMed1993

Repair of a proximal metatarsal Salter type-II fracture in a foal.

Bilateral radiographically persistent proximal third metatarsal physes and concurrent cuboidal bone immaturity were identified in a foal. Repair of a Salter type-II fracture of the left proximal third metatarsal physis was accomplished by use of lag screw fixation. A 6-day-old Arabian foal, intended for use as a show horse, was referred because of severe unilateral hind limb lameness and valgus deformity. A Salter type-II fracture of the proximal portion of the third metacarpal bone was identified radiographically and repaired by use of cancellous lag screws. The fractured limb was further supported with a modified Robert Jones bandage and fiberglass tube cast. Eight weeks after surgery, the colt was sound at a trot and had minimal valgus deformity. At this time, radiography revealed healing of the fracture and implants were removed. Six months after fracture repair, the outcome was considered successful on the basis of a desirable cosmetic result and no detectable lameness at a trot. The proximal third metatarsal physis is generally not radiographically visible in the neonate. This report describes the identification and successful repair of a fracture involving this persistent physis. Other sites of skeletal immaturity were also identified, and should be considered in the evaluation and management of unusual physeal fractures.

Animals↗

PubMed1993

Neuropeptidergic innervation of equine synovial joints.

Immunocytochemical analysis of equine synovial membranes revealed presence of several neuropeptides, including substance P (SP), neurokinin A, and neuropeptide Y, in nerves of the radiocarpal, middle carpal, and metacarpophalangeal (fetlock) joints. Within the subsynovium, these neuropeptides were located perivascularly, whereas in the fronds, only neuropeptide Y was restricted to the vessels of the synovial membrane. Only SP and neurokinin A were found in the intimal layer. The intimal layer of the metacarpophalangeal joint contained more SP-immunoreactive fibers than were observed in the intimal layer of the radiocarpal joint. Substance P also was detected in the synovial fluid from all 3 joints, but mean +/- SD concentrations were significantly different only between the middle carpal joint (37.56 +/- 5.48 fmol/ml; n = 6) and the metacarpophalangeal joint (55.80 +/- 8.33 fmol/ml; n = 5) and between the middle carpal joint and the radiocarpal joint (52.43 +/- 14.60 fmol/ml; n = 7).

Animals↗