Outcome of bilateral equid laparoscopic ovariectomies.

OBJECTIVE: To assess outcomes and behavior changes associated with bilateral laparoscopic ovariectomies. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Fifty-one equids. METHODS: Medical records were evaluated from equid bilateral laparoscopic ovariectomies from January 2012 to October 2018 with a potential of 6 months follow-up. Follow-up information obtained by telephone interviews included behavior before and after surgery. Likelihood ratio chi-square tests and odds ratios (OR) with 95% CI were calculated where applicable, with statistical significance at p < .05. RESULTS: Bilateral ovariectomy was performed in 51 cases, with elective (no pathologic ovaries) ovariectomies performed in 41/51 cases. Occasional estrus-like behavior was observed postoperatively in 14/51 (27%) mares, but the behavior was mild and manageable in all cases. There was no age effect on outcome in all bilateral (p = .56) or elective only (p = .36) cases. In 37/41 (90%) elective cases, improvement was observed in the reason for presentation. Some response to altrenogest administration for behavior modification was observed preoperatively in 12/18 (67%) elective cases. Response to altrenogest was not associated with (p = .31) or able to predict a beneficial response to surgery (OR = 5.5; 95% CI = 0.38-78.57; p = .21). CONCLUSION: Response to altrenogest in elective cases may not predict behavioral outcome with ovariectomy. Occasional estrus-like behavior in mares postoperatively was not problematic for any owners. Bilateral ovariectomy is a viable treatment option for owners seeking to alleviate undesirable behavior in mares. CLINICAL SIGNIFICANCE: This study should aid veterinarians and horse owners in case selection for bilateral ovariectomy.

Muscle tears as a primary cause of lameness in horses: 14 cases (2009-2016).

This study describes clinical and ultrasonographic findings and outcomes of horses with lameness associated with muscle tears. Records of horses diagnosed with muscle tears were retrospectively evaluated. Horses in which one or more muscle tears were confirmed ultrasonographically and lameness was associated with the tear were included in the study (n = 14). Eight horses had tearing of a single muscle, 6 horses had 2 or more muscles involved. Twelve of 14 horses survived to discharge and were alive at follow-up (8 to 90 months). Recovery time ranged from 6 to 52 weeks (mean: 19.8 weeks); 6 to 16 weeks for single muscle injuries and 12 to 52 weeks for multiple muscle injuries. Of the 12 long-term survivors 3 had chronic lameness/stiffness preventing return to their previous activity level and 9 returned to equal or greater level of activity. No statistically significant difference existed between outcomes and location of injury or number of muscles injured. Key clinical message: This study indicates that conservative management of muscle tears can result in favorable long-term outcomes.

Déchirures musculaires comme cause primaire de boiterie chez des chevaux: 14 cas (2009­2016). La présente étude décrit les trouvailles cliniques et échographiques ainsi que le devenir de chevaux avec une boiterie associée à des déchirures musculaires. Les dossiers de chevaux diagnostiqués avec une déchirure musculaire furent rétrospectivement évalués. Les chevaux chez qui une ou plusieurs déchirures musculaires furent confirmées par échographie et dont la boiterie était associée avec la déchirure furent inclus dans l'étude (n = 14). Huit chevaux avaient une déchirure de seulement un muscle, 6 chevaux avaient 2 muscles ou plus d'impliqués. Douze des 14 chevaux ont survécu jusqu'au congé et étaient vivants lors du suivi (8 à 90 mois). Le temps de guérison varia de 6 à 52 semaines (moyenne: 19,8 semaines); 6 à 16 semaines pour une blessure à seulement un muscle et 12 à 52 semaines pour des blessures musculaires multiples. Parmi les 12 survivants à long-terme, trois avaient une boiterie chronique/raideur empêchant un retour à leur niveau d'activité antérieur et neuf retournèrent à un niveau d'activité égal ou plus grand. Aucune différence statistiquement significative n'existait entre le devenir des chevaux et la localisation de la blessure ou le nombre de muscles blessés.Message clinique clé:Cette étude démontre qu'une gestion conservatrice des déchirures musculaires peut résulter en une issu favorable à long terme.(Traduit par Dr Serge Messier).

Osteochondritis Dissecans Development.

This article reviews current knowledge of osteochondritis dissecans (OCD) development in horses, including normal cartilage development, early osteochondrosis pathogenesis, and factors that result in healing or advancement to OCD fragments. Discussion includes current theories, detection, and therapeutic options.

Carpal valgus in llamas and alpacas: Retrospective evaluation of patient characteristics, radiographic features and outcomes following surgical treatment.

This study evaluated outcomes of surgical treatment for carpal valgus in New World camelids and correlated successful outcome (absence of carpal valgus determined by a veterinarian) with patient characteristics and radiographic features. Univariable and multivariable analyses of retrospective case data in 19 camelids (33 limbs) treated for carpal valgus between 1987 and 2010 revealed that procedures incorporating a distal radial transphyseal bridge were more likely (P = 0.03) to result in success after a single surgical procedure. A greater degree of angulation (> 19°, P = 0.02) and younger age at surgery (< 4 months, P = 0.03) were associated with unsuccessful outcome. Overall, 74% of limbs straightened, 15% overcorrected, and 11% had persistent valgus following surgical intervention. To straighten, 22% of limbs required multiple procedures, not including implant removal. According to owners, valgus returned following implant removal in 4 limbs that had straightened after surgery.

Valgus carpien chez les lamas et les alpagas : évaluation rétrospective des caractéristiques des patients, des radiographies et des résultats après un traitement chirurgical. Cette étude a évalué les résultats du traitement chirurgical pour le valgus carpien chez des camélidés du nouveau monde et a établi une corrélation entre les résultats fructueux (absence de valgus carpien déterminée par un vétérinaire) et les caractéristiques du patient et des radiographies. Des analyses à variable unique et à variables multiples des données de cas rétrospectifs chez 19 camélidés (33 jambes) traités pour le valgus carpien entre 1987 et 2010 ont révélé que les procédures intégrant un pont radial distal transphyséal présentaient une plus grande probabilité de succès (P = 0,03) après une seule intervention chirurgicale. Une déviation supérieure (> 19°, P = 0,02) et un jeune âge à la chirurgie (< 4 mois, P = 0,03) étaient associés à des échecs. Dans l'ensemble, 74 % des jambes ont été redressés, 15 % ont été corrigées et 11 % présentaient un valgus persistant après l'intervention chirurgicale. Pour le redressement, 22 % des jambes ont nécessité des procédures multiples, ce qui n'incluait pas l'enlèvement de l'implant. Selon les propriétaires, le valgus est réapparu après l'enlèvement de l'implant dans 4 jambes qui avaient été redressées après la chirurgie.(Traduit par Isabelle Vallières).

Comparison of differential protein expression of the marginal transitional zone in neonatal and weanling-aged foals.

The marginal transitional zone (MTZ) is peripherally located within the diarthrodial joint, and represents the junction of synovium, fibrous joint capsule, articular cartilage, periosteum, and bone. The purpose of this study is to characterize age-related differences in protein expression of matrix and molecular regulators in the marginal transitional zone of neonatal and weanling foals. Several families of proteins with known roles in cartilage and bone development are investigated, including matrix molecules, members of the Wnt signaling family, apoptotic factors and paracrine cell signaling molecules. Our results demonstrate differential protein expression in the marginal transitional zone from the lateral femoral trochlear ridge of neonatal and weanling foals. Protein expression of several paracrine signaling molecules (Ihh, PTHrP, PDGF, VEGF, ß-catenin, cytochrome C) within MTZ cartilage is higher in weanling-aged foals. Collagen type II and lubricin expression is similarly greater in weanling-aged foals, while matrix metalloproteinases are lower, likely reflecting the remodeling that occurs during cartilage development as increasing forces are placed on cartilage.

Differential Protein Expression of the Marginal Transitional Zone in Foals with Osteochondrosis.

The marginal transitional zone is peripherally located within the diarthrodial joint, and represents the interface of articular cartilage, periosteum, and the fibrous joint capsule. The purpose of this study is to characterize the protein expression of matrix and molecular regulators in the marginal transitional zone of foals having osteochondrosis (OC) compared to normal foals. Several families of proteins with known roles in cartilage and bone development are investigated, including matrix molecules, Wnt signaling, apoptotic factors and paracrine cell signaling molecules. Our results demonstrate differential protein expression in the marginal transitional zone from the lateral femoral trochlear ridge of foals affected by osteochondrosis. Alterations in protein expression of OC-affected foals mainly involve components of extracellular matrix homeostasis and canonical Wnt signaling. Matrix expression of collagen type IIB and lubricin are decreased and matrix metalloproteinase-3 expression is increased in OC-affected marginal transitional zone samples. Canonical Wnt signaling is inhibited in OC-affected marginal transitional zone samples, based on increased Dickkopf-1 and decreased ß-catenin protein expression. Most apoptotic and paracrine signaling proteins are not altered in OC-affected marginal transitional zone samples.

Molecular, histologic, and trace mineral characterization of metacarpophalangeal and metatarsophalangeal joint hyperextension in juvenile llamas.

OBJECTIVE: To evaluate molecular and histologic characteristics of the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), and suspensory ligament (SL) and assess trace-mineral concentrations in serum, liver, and hair of juvenile llamas with metacarpophalangeal and metatarsophalangeal joint hyperextension. ANIMALS: 12 juvenile llamas (6 with bilateral hyperextension of metacarpophalangeal joints, metatarsophalangeal joints, or both and 6 clinically normal control llamas). PROCEDURES: Radiography and ultrasonography of metacarpophalangeal and metatarsophalangeal regions were performed. Llamas were euthanized, and SDFT, DDFT, and SL samples were collected for histologic evaluation of collagen and elastin content and orientation, proteoglycan content, and collagen type III immunohistochemistry. Total RNA was isolated from SL tissue, and gene expression of collagen types I and III, lysyl oxidase, and matrix metalloproteinase-13 was evaluated via real-time quantitative reverse transcriptase PCR assay. Liver, serum, and hair samples were evaluated for trace mineral content. RESULTS: Collagen type III gene expression and proteoglycan content were significantly increased in SL samples of affected juvenile llamas, compared with those of control llamas. No difference was detected in collagen and elastin content and orientation or in gene expression of collagen type I, lysyl oxidase, or matrix metalloproteinase-13 between groups. Affected llamas had significantly increased serum molybdenum and decreased liver cobalt concentrations, compared with values for control llamas. CONCLUSIONS AND CLINICAL RELEVANCE: Increased collagen type III gene expression and proteoglycan content in SL samples of affected juvenile llamas provided evidence of ongoing SL matrix repair. Trace mineral differences may have been attributable to dietary imbalances in affected llamas.

Molecular and histologic evaluation of idiopathic hyperextension of the metacarpophalangeal and metatarsophalangeal joints in adult llamas.

OBJECTIVE: To determine the molecular and histologic characteristics of hyperextension of the metacarpophalangeal and metatarsophalangeal joints in adult llamas. ANIMALS: 12 adult llamas (6 with bilateral hyperextension of the metacarpophalangeal or metatarsophalangeal joints [affected] and 6 age- and sex-matched clinically normal control llamas). PROCEDURES: Llamas were euthanized, and specimens of superficial digital flexor tendon, deep digital flexor tendon, and suspensory ligament were obtained from 4 areas and snap frozen in liquid nitrogen or suspended in neutral-buffered 10% formalin. Histologic evaluation of collagen fiber orientation, elastin content, and proteoglycan content was performed by use of Masson trichrome, picrosirius red, Verhoeff, and Alcian blue stains. Total RNA was isolated from frozen suspensory ligament specimens. Gene expression of collagen types I and III, lysyl oxidase, and matrix metalloproteinase-13 was evaluated with a real-time quantitative reverse transcriptase PCR assay. RESULTS: Gene expression of collagen types I and III, lysyl oxidase, and matrix metalloproteinase-13 in suspensory ligaments was similar between affected and control llamas. Collagen orientation and elastin content of the flexor tendons and suspensory ligaments were also similar between the groups. Proteoglycan content was low in most specimens but was focally increased in discrete lesions of suspensory ligaments in 2 affected and 2 control llamas. CONCLUSIONS AND CLINICAL RELEVANCE: Hyperextension of the metacarpophalangeal or metatarsophalangeal joints in llamas did not appear to be caused by degeneration or inflammation of the suspensory ligament. Although focal proteoglycan accumulation existed in the suspensory ligaments of 2 affected llamas, widespread abnormal connective tissue proteoglycan accumulation was not found.

Complications after orthopedic surgery in alpacas and llamas: 24 cases (2000-2006).

OBJECTIVE: To report complications associated with orthopedic surgery in alpacas and llamas. STUDY DESIGN: Retrospective study. ANIMALS: Alpacas (n=18) and llamas (n=6) that orthopedic surgery using internal or external fixation. METHODS: Medical records (January 2000-December 2006) and radiographs were reviewed and owners contacted for follow-up information for alpacas and llamas that had orthopedic surgery involving internal or external fixation. Fourteen camelids had internal fixation, 7 had external fixation, and 3 had a combination of internal and external fixation. RESULTS: Twenty-two animals (92%) were discharged after surgery (mean hospitalization, 15 days). Of 20 animals with >or=1 year follow-up information, 18 were alive (82%). Postoperative complications related to fracture healing, infection, soft tissue structures, or joints occurred in 21 camelids (87%). Thirteen animals returned to their intended use, 4 animals returned to breeding but not their intended use, 4 were euthanatized, and 3 were only able to be used as pets. CONCLUSIONS: Fixation type (internal, external) did not have any significant effect on complications involving fracture healing, infection, soft tissue structures, or chronic lameness. Camelids with open fractures were more likely to have complications associated with fracture healing, repair, and infection than closed fractures. CLINICAL RELEVANCE: Complications after orthopedic surgery in alpacas and llamas are more common than previously reported and may result in chronic lameness or prevent return to their intended use.

Expression of pro-apoptotic markers is increased along the osteochondral junction in naturally occurring osteochondrosis.

Osteochondrosis (OC) is a naturally occurring disease of the articular-epiphyseal cartilage and subchondral bone layers, leading to pain and decreased mobility. The objective of this study was to characterize gene and protein expression of apoptotic markers in chondrocytes surrounding cartilage canals and along the osteochondral junction of osteochondrosis (OC)-affected and normal cartilage, using naturally occurring disease in horses. Paraffin-embedded osteochondral samples (6 OC, 8 normal controls) and cDNA from chondrocytes captured with laser capture microdissection (4 OC, 6 normal controls) were obtained from the lateral trochlear ridge of femoropatellar joints in 14 immature horses (1-6 months of age). Equine-specific caspase-3, caspase-8, caspase-10, Fas, Bcl-2, BAG-1, TNFα, cytochrome C, thymosin-ß10, and 18S mRNA expression levels were evaluated by two-step real-time quantitative PCR. Percentage of cell death was determined using the TUNEL method. Protein expression of caspase-10, Fas, cytochrome C, and thymosin-ß10 was determined following immunohistochemistry. Statistical analysis was performed using the Wilcoxon rank sum test or two-sample t-test (p < 0.05). In OC samples, there was significantly increased gene expression of caspase-10, Fas, cytochrome C, and thymosin-ß10 in chondrocytes along the osteochondral junction and increased Fas gene expression in chondrocytes adjacent to cartilage canals, compared to controls. In OC samples, higher matrix Fas and cytochrome C protein expression, lower mitochondrial cytochrome C protein expression, and a trend for higher cytoplasmic caspase-10 protein expression were found. Collectively, these results suggest that both extrinsic and intrinsic apoptotic pathways are activated in OC cartilage. Increased apoptosis of osteochondral junction chondrocytes may play a role in OC, based on increased gene expression of several pro-apoptotic markers in this location.

Morphologic and biochemical characterization of hyperextension of the metacarpophalangeal and metatarsophalangeal joints in llamas.

OBJECTIVE: To determine the morphologic and biochemical characteristics of hyperextension of the metacarpophalangeal and metatarsophalangeal joints in llamas. ANIMALS: 12 adult llamas (6 with bilateral hyperextension of the metacarpophalangeal or metatarsophalangeal joints and 6 age- and sex-matched control llamas). PROCEDURES: Llamas were evaluated by use of lameness examination, ultrasonography, and radiography. A CBC, serum biochemical analysis, and determination of concentrations of trace minerals in serum and liver samples were performed. Llamas were euthanized, and samples of the superficial digital flexor tendon, deep digital flexor tendon, and suspensory ligament were obtained from 4 areas and snap-frozen in liquid nitrogen or suspended in neutral-buffered 10% formalin. Immunohistochemical evaluation of collagen types I and III and assays for measurement of lysyl oxidase activity were performed. RESULTS: 2 affected llamas had a visible gait deficit associated with metacarpophalangeal joint hyperextension. Radiographic evidence of osteoarthritis was detected in 1 severely affected llama, and ultrasonographic changes of soft tissue mineralization and suspensory desmitis were observed in 2 llamas. Liver concentrations of copper were lower and serum concentrations of zinc higher in affected llamas, compared with values in control llamas. Lysyl oxidase activity and collagen distribution did not differ significantly between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Hyperextension of the metacarpophalangeal or metatarsophalangeal joints in llamas does not appear to be the result of injury or degeneration of the suspensory ligament or flexor tendons. Lower copper concentrations coupled with higher zinc concentrations in affected llamas may be indicative of secondary copper deficiency.

Age-related expression of molecular regulators of hypertrophy and maturation in articular cartilage.

The purpose of this study was to determine changes in the expression of regulatory molecules in normal equine articular cartilage throughout development up to 18 months of age. The hypothesis was that expression of these regulatory molecules would decrease from birth to postpubescence. Cartilage was harvested from normal femoropatellar or scapulohumeral joints from 34 fresh horse cadavers. Horses were placed in four age groups [prenatal (n = 5); prepubertal, 0-6 months (n = 11); pubertal, 7-14 months (n = 13); and postpubertal, 15-18 months (n = 5)]. Indian hedgehog (Ihh), Gli1, Gli3, Patched1 (Ptc1), Smoothened (Smo), Noggin, bone morphogenetic protein-6 (BMP-6), BMP-2, parathyroid hormone-related peptide (PTHrP), and PTH/PTHrP receptor mRNA expression levels were evaluated by real-time quantitative PCR. Spatial tissue mRNA and protein expression was determined by in situ hybridization and immunohistochemistry. The expression of PTHrP decreased (p = 0.002) in the pubertal group, while PTH/PTHrP receptor expression significantly increased (p = 0.001). No significant difference was found between groups for Ihh (p = 0.6) or Smo (p = 0.3) expression. In contrast, there was significantly increased expression of Ptc1 (p = 0.006), Gli1 (p = 0.04), and Gli3 (p = 0.007) in the pubertal group, and Gli3 (p = 0.007) remained elevated in the postpubertal group. The expression of BMP-6 significantly increased from prenatal to postnatal groups (p = 0.03) while BMP-2 expression increased during puberty and postpuberty (p = 0.03). The changes in expression of hedgehog and BMP signaling molecules in articular cartilage during postnatal development have not been shown previously. The increased expression of hedgehog receptor and transcription factors during puberty may indicate maturation of the deep articular layer during this time period.

Goniometrie evaluation of standing extension and maximum flexion joint angles of llamas and alpacas.

OBJECTIVE To determine and compare mean standing extension and maximum flexion angles of various joints in healthy adult alpacas and llamas, and determine the reliability of goniometric data within and between 2 observers for each joint of interest. SAMPLE 6 healthy adult llamas and 6 healthy adult alpacas. PROCEDURES The shoulder joint, elbow joint, carpal, and metacarpophalangeal (MCP) joints of the forelimbs and the hip joint, stifle joint, tarsal, and metatarsophalangeal (MTP) joints of the hind limbs were investigated. Each articulation was measured with a universal goniometer by 2 observers, who each obtained 2 measurements when each joint was maintained in standing extension and in maximal passive flexion. Two sample (unpaired) t tests were performed for comparisons of mean standing extension and maximum passive flexion angles between alpacas and llamas. Intraclass correlation coefficients were calculated for each articulation to assess interobserver and intra-observer reliability of measurements. RESULTS Llamas had larger mean standing extension angles than alpacas for the tarsal and elbow joint, but there were no significant differences between species for all other joints. For all joints, flexion measurements did not differ significantly between the 2 species. For most joints, the reliability of goniometric data between observers was good to excellent (intraclass correlation coefficients, 0.6 to 0.95) CONCLUSIONS AND CLINICAL RELEVANCE Except for the elbow joint and tarsus in extension, the angle of limb articulations during flexion and extension can be considered similar for alpacas and llamas. These measurements have relevance for veterinary surgeons when assessing joint mobility and conformation and determining appropriate angles for arthrodesis.

Evaluation of two platelet-rich plasma processing methods and two platelet-activation techniques for use in llamas and alpacas.

OBJECTIVE To evaluate 2 processing methods (commercial kit vs conical tube centrifugation) for preparing platelet rich plasma (PRP) for use in llamas and alpacas. SAMPLES Blood samples (30 mL each) aseptically collected from 6 healthy llamas and 6 healthy alpacas. PROCEDURES PRP was prepared from blood samples by use of a commercial kit and by double-step conical tube centrifugation. A CBC was performed for blood and PRP samples. Platelets in PRP samples were activated by means of a freeze-thaw method with or without 23mM CaCl2, and concentrations of platelet-derived growth factor-BB and transforming growth factor-ß1 were measured. Values were compared between processing methods and camelid species. RESULTS Blood CBC values for llamas and alpacas were similar. The commercial kit yielded a significantly greater degree of platelet enrichment (mean increase, 8.5 fold vs 2.8 fold) and WBC enrichment (mean increase, 3.7 fold vs 1.9 fold) than did conical tube centrifugation. Llamas had a significantly greater degree of platelet enrichment than alpacas by either processing method. No difference in WBC enrichment was identified between species. Concentrations of both growth factors were significantly greater in PRP samples obtained by use of the commercial kit versus those obtained by conical tube centrifugation. CONCLUSIONS AND CLINICAL RELEVANCE For blood samples from camelids, the commercial kit yielded a PRP product with a higher platelet and WBC concentration than achieved by conical tube centrifugation. Optimal PRP platelet and WBC concentrations for various applications need to be determined for llamas and alpacas.

Expression patterns of hedgehog signaling peptides in naturally acquired equine osteochondrosis.

Hypertrophic differentiation and endochondral ossification of growth cartilage are regulated by a complex array of signaling peptides, including parathyroid hormone-related protein (PTH-rP), Indian hedgehog (Ihh), and bone morphogenetic proteins (BMPs). This study investigated the expression of Ihh, Patched1 and 2 (Ptc1, Ptc2), Smoothened (Smo), Gli1, and Gli3, in naturally acquired articular osteochondrosis, using an equine model. Cartilage was harvested from osteochondrosis (OC) affected femoropatellar or scapulohumeral joints from immature horses and normal control horses of similar age. Ihh, Ptc1, Smo, Gli1, and Gli3 mRNA expression levels were evaluated by real-time quantitative PCR. Spatial tissue expression was determined by in situ hybridization for Ihh and Smo and immunohistochemistry for Ptc1 and Ptc2. The expression of Ihh was significantly increased in OC cartilage compared to normal control cartilage and was localized mainly to the deep layer of articular cartilage, just above the calcified zone, with some mild expression also present in the middle cartilage layer. The expression of Gli1 was significantly decreased in OC samples, but there was no significant difference in expression of Gli3, Ptc1 and Smo in OC cartilage compared to normal cartilage. The expression of Ptc1 protein was present at the junction of deep and calcified layers, while Ptc2 protein was expressed throughout the middle, deep, and calcified cartilage layers. Spatial expression of Smo was variable between animals and confined mainly to the middle and deep layers when present. Half of the OC samples displayed areas of moderate to strong Smo expression compared to mild or minimal expression in normal controls. The increased Ihh expression in OC suggests a role of Ihh in diseased cartilage, although it is not known if a PTH-rP/Ihh feedback cycle exists in articular cartilage. The disparity between increased Ihh expression and decreased Gli1 expression in OC cartilage suggests a different primary transcription factor for Ihh or the presence of an elevated Ihh inhibitor in these tissues.

Determination of the anatomic communications among compartments within the carpus, metacarpophalangeal and metatarsophalangeal joints, stifle joint, and tarsus in llamas.

OBJECTIVE: To determine the anatomic communications among compartments within the carpus, metacarpophalangeal and metatarsophalangeal joints, stifle joint, and tarsus in llamas. SAMPLE POPULATION: 88 limbs from 22 llamas necropsied because of reasons unrelated to disease of the carpus; tarsus; or metacarpophalangeal, metatarsophalangeal, or stifle joints. PROCEDURE: 1 compartment (randomly assigned) of each joint was injected with blue latex solution. Communication between joint compartments was determined by observation of latex in adjacent compartments following frozen sectioning. RESULTS: Of the 44 carpi, 30 (68%) had anatomic separation between the radiocarpal and middle carpal joints, whereas the remaining 14 (32%) had communication between the radiocarpal and middle carpal joints. In the metacarpophalangeal or metatarsophalangeal joints, medial and lateral joint compartments remained separate in 83 of 88 (94%) joints injected. The tibiotarsal and proximal intertarsal joints communicated in all tarsi examined, whereas 14 of 38 (37%) communicated between the proximal intertarsal and distal intertarsal joints. Communication between the distal intertarsal and tarsometatarsal joints was detected in 17 of 25 (68%) specimens; all 4 tarsal joints communicated in 11 of 42 (26%) specimens examined. Examination of 33 stifle joints that were successfully injected revealed communication between the femoropatellar, medial femorotibial, and lateral femorotibial joints. CONCLUSIONS AND CLINICAL RELEVANCE: These data suggest that it is important to determine the joint communications specific to each llama prior to treatment of septic arthritis. The metacarpophalangeal or metatarsophalangeal joint compartments may be considered separate, although the lateral and medial compartments infrequently communicate along the proximal palmar or plantar aspect.

Wnt/ß-catenin signaling of cartilage canal and osteochondral junction chondrocytes and full thickness cartilage in early equine osteochondrosis.

The objective of this study was to elucidate gene and protein expression of Wnt signaling molecules in chondrocytes of foals having early osteochondrosis (OC) versus normal controls. The hypothesis was that increased expression of components of Wnt signaling pathway in osteochondral junction (OCJ) and cartilage canal (CC) chondrocytes would be found in early OC when compared to controls. Paraffin-embedded osteochondral samples (7 OC, 8 normal) and cDNA from whole cartilage (7 OC, 10 normal) and chondrocytes surrounding cartilage canals and osteochondral junctions captured with laser capture microdissection (4 OC, 6 normal) were obtained from femoropatellar joints of 17 immature horses. Equine-specific Wnt signaling molecule mRNA expression levels were evaluated by two-step real-time qPCR. Spatial tissue protein expression of ß-catenin, Wnt-11, Wnt-4, and Dkk-1 was determined by immunohistochemistry. There was significantly decreased Wnt-11 and increased ß-catenin, Wnt-5b, Dkk-1, Lrp6, Wif-1, Axin1, and SC-PEP gene expression in early OC cartilage canal chondrocytes compared to controls. There was also significantly increased ß-catenin gene expression in early OC osteochondral junction chondrocytes compared to controls. Based on this study, abundant gene expression differences in OC chondrocytes surrounding cartilage canals suggest pathways associated with catabolism and inhibition of chondrocyte maturation are targeted in early OC pathogenesis.

Parathyroid hormone-related peptide and indian hedgehog expression patterns in naturally acquired equine osteochondrosis.

Early changes in parathyroid hormone-related peptide (PTH-rP) and Indian hedgehog (Ihh) expression were examined in equine articular osteochondrosis (OC) as a model of a naturally acquired dyschondroplasia. Cartilage was harvested from OC-affected femoropatellar or scapulohumeral joints from immature horses and normal control horses of similar age. PTH-rP expression levels were assessed by semi-quantitative PCR, in situ hybridization, and immunohistochemistry. Ihh protein expression levels were assessed by immunohistochemistry. Elevated PTH-rP protein and mRNA expression were identified in the deeper layers of affected articular cartilage and the fibrous tissue of interposing clefts. These changes were confined to the chondrocytes in the OC-affected cartilage, which had significantly increased PTH-rP protein and mRNA expression when compared to control cartilages. Ihh protein expression showed similar distribution as PTH-rP in the deeper layers of articular cartilage; however, only a trend for increased Ihh immunostaining was evident in the OC cartilage when compared to the normal cartilage. Increased PTH-rP expression in prehypertrophic chondrocytes of diseased OC cartilage suggests a possible link between this peptide and the delayed ossification, which is a consistent histologic alteration in OC. More evidence is necessary to determine the role of Ihh in articular cartilage and if a similar feedback cycle exists as previously described for the growth plate.

Insulin-like growth factor-I diminishes the activation status and expression of the small GTPase Cdc42 in articular chondrocytes.

Insulin-like growth factor-I (IGF-I) is an important anabolic growth factor in the maintenance of articular cartilage phenotypic expression. Chondrocyte morphology is also tightly linked to phenotype. The small G-protein Cdc42 plays a key role in regulation of cell morphology and phenotypic expression in several cell types and, we show here, in articular chondrocytes. The purpose of these studies was to investigate possible links between the intracellular signaling pathways of IGF-I and Cdc42 in articular chondrocytes. Treatment of chondrocytes with IGF-I resulted in a rapid and sustained decrease in the activation state (decreased GTP-bound) of Cdc42. Nucleotide exchange and hydrolysis experiments suggest that the decreased activation occurs through increased hydrolysis. Transient expression of dominant-negative Cdc42(T17N) allowed for enhanced expression of normal chondrocyte phenotype as determined by increased mRNA expression of collagen type II (Coll II) with decreased matrix metalloproteinase-3 (MMP-3) expression. The results of these studies suggest a novel link between IGF-I and Cdc42 signaling pathways. Further, an additional mechanism for the regulation of chondrocyte phenotype is defined through the IGF-I induced down-regulation of Cdc42 activation.

Expression of bone morphogenetic protein-6 and -2 and a bone morphogenetic protein antagonist in horses with naturally acquired osteochondrosis.

OBJECTIVE: To determine the mRNA expression of bone morphogenetic protein (BMP)-6 and -2 and a BMP antagonist (Noggin) in horses with osteochondrosis. SAMPLE POPULATION: Samples of articular cartilage from affected stifle or shoulder joints of 10 immature horses with naturally acquired osteochondrosis and corresponding joints of 9 clinically normal horses of similar age; additionally, samples of distal femoral growth plate cartilage and distal femoral articular cartilage were obtained from a normal equine fetus. PROCEDURE: Cartilage specimens were snap-frozen in liquid nitrogen, and total RNA was isolated. Adjacent specimens were fixed in 4% paraformaldehyde for histologic examination. Expression of BMP-6, BMP-2, and Noggin mRNA was evaluated by real-time quantitative polymerase chain reaction (PCR) assays. Spatial tissue mRNA expression of BMP-6 was determined by in situ hybridization. RESULTS: Nucleotide sequences were obtained for portions of the BMP-6 propeptide and mature peptide region, as well as the signal and mature peptide region of Noggin. Expression of BMP-6, BMP-2, and Noggin mRNA was found to be similar in cartilage from normal and osteochondrosis-affected horses. Spatial expression of BMP-6 correlated with the middle and deep layers of articular cartilage; no differences were observed in overall expression between cartilage specimens from the 2 groups of horses. No expression of BMP-6 was found in the superficial layer, subchondral bone, or osteochondrosis-affected cleft fibrous tissue. CONCLUSIONS AND CLINICAL RELEVANCE: Although these signaling peptides may play important roles in cartilage differentiation, results did not provide evidence to suggest that they are involved in the disease process of osteochondrosis.