A metabolomics perspective on 2 years of high-intensity training in horses.

The plasma metabolomic profile of elite harness horses subjected to different training programmes was explored. All horses had the same training programme from 1.5 until 2 years of age and then high-intensity training was introduced, with horses divided into high and low training groups. Morning blood samples were collected at 1.5, 2, 2.5 and 3.5 years of age. The plasma was analysed using targeted absolute quantitative analysis and a combination of tandem mass spectrometry, flow-injection analysis and liquid chromatography. Differences between the two training groups were observed at 2 years of age, when 161 metabolites and sums and ratios were lower (e.g. ceramide and several triglycerides) and 51 were higher (e.g. aconitic acid, anserine, sum of PUFA cholesteryl esters and solely ketogenic AAs) in High compared with low horses. The metabolites aconitic acid, anserine, leucine, HArg synthesis and sum of solely ketogenic AAs increased over time, while beta alanine synthesis, ceramides and indole decreased. Therefore high-intensity training promoted adaptations linked to aerobic energy production and amino acid metabolism, and potentially also affected pH-buffering and vascular and insulin responses.

A randomized, triple-blinded controlled clinical study with a novel disease-modifying drug combination in equine lameness-associated osteoarthritis.

Objective: This study aimed to test a novel treatment combination (TC) (equivalent to sildenafil, mepivacaine, and glucose) with disease-modifying properties compared to Celestone® bifas® (CB) in a randomized triple-blinded phase III clinical study in horses with mild osteoarthritis (OA). Joint biomarkers (reflecting the articular cartilage and subchondral bone remodelling) and clinical lameness were used as readouts to evaluate the treatment efficacy. Methods: Twenty horses with OA-associated lameness in the carpal joint were included in the study and received either TC (n = 10) or CB (n = 10) drug intra-articularly-twice in the middle carpal joint with an interval of 2 weeks (visit 1 & 2). Clinical lameness was assessed both objectively (Lameness locator) and subjectively (visually). Synovial fluid and serum were sampled for quantification of the extracellular matrix (ECM) neo-epitope joint biomarkers represented by biglycan (BGN262) and cartilage oligomeric matrix protein (COMP156). Another two weeks later clinical lameness was recorded, and serum was collected for biomarkers analysis. The overall health status was compared pre and post-intervention by interviewing the trainer. Results: Post-intervention, SF BGN262 levels significantly declined in TC (P = 0.002) and COMP156 levels significantly increased in CB (P = 0.002). The flexion test scores improved in the TC compared to CB (P =0.033) and also had an improved trotting gait quality (P =0.044). No adverse events were reported. Conclusion: This is the first clinical study presenting companion diagnostics assisting in identifying OA phenotype and evaluating the efficacy and safety of a novel disease-modifying osteoarthritic drug.

The epidemiology of upper respiratory tract disorders in a population of insured Swedish dogs (2011-2014), and its association to brachycephaly.

Upper respiratory tract (URT) disorders are common in dogs but neither general nor breed-related epidemiological data are widely reported. This study´s aims were to describe the epidemiology of URT disorders in a Swedish population of dogs and to investigate whether brachycephalic breeds were overrepresented among high-risk breeds. A cohort of dogs insured by Agria Djurförsäkring in Sweden (2011-2014) was used to calculate overall and breed-specific incidence rate (IR), age at first URT diagnosis and relative risk (RR) for URT disorders. For breeds with high RR for URT disorders, co-morbidities throughout the dog's insurance period and age at death were investigated. The cohort included approximately 450,000 dogs. URT disorders had an overall IR of 50.56 (95% CI; 49.14-52.01) per 10,000 dog years at risk. Among 327 breeds, the English bulldog, Japanese chin, Pomeranian, Norwich terrier and pug had highest RR of URT disorders. Eight of 13 breeds with high RR for URT disorders were brachycephalic. The median age at first URT diagnosis was 6.00 years (interquartile range 2.59-9.78). French bulldogs with URT diagnoses had a significantly shorter life span (median = 3.61 years) than other breeds with URT diagnosis (median = 7.81 years). Dogs with high risk for URT disorders had more co-morbidities than average.

Salivary biglycan-neo-epitope-BGN262: A novel surrogate biomarker for equine osteoarthritic sub-chondral bone sclerosis and to monitor the effect of short-term training and surface arena.

Objective: We aimed to delineate a novel soluble Biglycan Neo-epitope-BGN262 in saliva from young reference and osteoarthritic horses in conjunction with the influence of short-term training exercise, riding surface hardness, circadian rhythm, and feeding on its soluble levels. Design: A custom-made inhibition ELISA was used for the quantification of BGN262 in saliva. Cohort 1: A cross-sectional study comprising reference (N â€‹= â€‹19) and OA horses (N â€‹= â€‹9) with radiographically classified subchondral bone sclerosis. Receiver operating characteristic curve analysis was performed to evaluate the robustness of BGN262. Cohorts 2 (N â€‹= â€‹5) & 3 (N â€‹= â€‹7): Longitudinal studies of sampling during a short-term training exercise (sand-fibre) and a cross-over design of short-training exercise on 2 different riding arenas (sand and sand-fibre), respectively. Capillary western immunoassay was used to determine the BGN262 molecular size in a selection of saliva samples collected from cohort 1. Results: Cohort 1: Salivary BGN262 levels were significantly higher in the OA group. The Receiver operating characteristic curve analysis showed an area under the curve of 0.8304 [0.6386 to 1.022], indicating a good separation from the reference group. Cohorts 2 & 3: Salivary BGN262 levels significantly changed during the exercise on sand and sand-fibre arena, with a trend towards higher levels for sand-fibre. The size of the BGN262 fragment determined by Capillary western assay was 18 â€‹kDa. Conclusions: The data presented show saliva BGN262 levels as a novel biomarker in evaluating the influence of exercise, and interaction with riding arenas alongside assessing osteoarthritis severity.

Biglycan neo-epitope (BGN262), a novel biomarker for screening early changes in equine osteoarthritic subchondral bone.

OBJECTIVE: Native biglycan (BGN), which can undergo proteolytic cleavage in pathological conditions, is well known to be involved in bone formation and mineralization. This study aimed to delineate the specific cleavage fragment, a neo-epitope for BGN (BGN262), in synovial fluid (SF) from young racehorses in training, osteoarthritic (OA) joints with subchondral bone sclerosis (SCBS), and chip fracture joints. DESIGN: A custom-made inhibition ELISA was developed to quantify BGN262 in SF. Cohort 1: A longitudinal study comprising 10 racehorses undergoing long-term training. Cohort 2: A cross-sectional study comprising joints from horses (N = 69) with different stages of OA and radiographically classified SCBS. Cohort 3: A cross-sectional study comprising horses (N = 9) with chip fractures. Receiver operating characteristic (ROC) curve analysis was performed (healthy joints vs chip joints) to evaluate BGN262 robustness. RESULTS: Cohort 1: SF BGN262 levels from racehorses showed a statistical increase during the first 6 months of the training period. Cohort 2: BGN262 levels were significantly higher in the SF from severe SCBS joints. Cohort 3: SF BGN262 levels in chip fracture joints showed a significant increase compared to normal joints. The ROC analysis showed an AUC of 0.957 (95% C.I 0.868-1.046), indicating good separation between the groups. CONCLUSIONS: The data presented show that BGN262 levels increase in SF in correlation with the initiation of training, severity of SCBS, and presence of chip fractures. This suggests that BGN262 is a potential predictor and a novel biomarker for early changes in subchondral bone (SCB), aiming to prevent catastrophic injuries in racehorses.

Nerve growth factor in the equine joint.

Nerve growth factor (NGF) is a neurotrophin with many functions. In humans, it is involved in inflammation, nerve growth, apoptosis and pain signalling. Increased concentrations of NGF in synovial fluid has been shown in humans and dogs with osteoarthritis. Despite osteoarthritis being a common problem in horses, no studies have previously been published on NGF in the equine joint. The aim of this study was to quantify NGF in equine synovial fluid from healthy joints, acutely inflamed septic joints and joints with structural changes associated with osteoarthritis. A secondary aim was to identify the localisation of NGF and its two receptors, TrkA and p75NTR, in healthy and osteoarthritic articular cartilage. NGF concentrations in synovial fluid from osteoarthritic joints (n = 27), septic joints (n = 9) and healthy joints (n = 16) were determined by ELISA. In addition, articular cartilage from osteoarthritic and healthy joints was examined for NGF, TrkA and p75NTR using immunohistochemistry staining. NGF was present in equine synovial fluid and articular cartilage. Compared to synovial fluid from healthy joints, NGF concentration was higher in synovial fluid from joints with structural osteoarthritic changes (P = 0.032) or acute septic inflammation (P = 0.006). In articular cartilage with severe osteoarthritic changes, there was more abundant positive immunohistochemistry staining for NGF and its receptors than in normal articular cartilage. Further studies should focus on identifying precursor forms of NGF, and on receptor expression and downstream signalling of TrkA and P75NTR in health and disease.

Effect of circadian rhythm, age, training and acute lameness on serum concentrations of cartilage oligomeric matrix protein (COMP) neo-epitope in horses.

BACKGROUND: Molecular serum markers that can identify early reversible osteoarthritis (OA) in horses are lacking. OBJECTIVES: We studied serum concentrations of a novel cartilage oligomeric matrix protein (COMP) neo-epitope in horses subjected to short-term exercise and with acute lameness. The effects of circadian rhythm and age were also evaluated. STUDY DESIGN: Longitudinal studies in healthy horses and cross-sectional comparison of lame and non-lame horses. METHODS: Sera were collected from five horses before and after short-term interval exercise and during full-day box rest. Sera from 32 acutely lame horses were used to evaluate age-related effects. Independent samples from control horses (n = 41) and horses with acute lameness (n = 71) were included. COMP neo-epitope concentrations were analysed using custom-developed inhibition ELISAs validated for equine serum. The presence of COMP neo-epitope was delineated in healthy and osteoarthritic articular cartilage with immunohistochemistry. RESULTS: COMP neo-epitope concentrations decreased after speed training but returned to baseline levels post-exercise. No correlations between age and serum COMP neo-epitope concentrations were found (r = 0.0013). The mean (±s.d.) serum concentration of COMP neo-epitope in independent samples from non-lame horses was 0.84 ± 0.38 µg/mL, and for lame horses was 5.24 ± 1.83 µg/mL (P<0.001). Antibodies against COMP neo-epitope did not stain normal articular cartilage, but intracytoplasmic staining was found in superficial chondrocytes of mild OA cartilage and in the extracellular matrix of moderately osteoarthritic cartilage. MAIN LIMITATIONS: ELISA was based on polyclonal antisera rather than a monoclonal antibody. There is a sex and breed bias within the groups of horses, also it could have been of value to include horses with septic arthritis and tendonitis and investigated joint differences. CONCLUSIONS: This COMP neo-epitope can be measured in sera, and results indicate that it could be a biomarker for pathologic fragmentation of cartilage in connection with acute joint lameness.

Cartilage oligomeric matrix protein neoepitope in the synovial fluid of horses with acute lameness: A new biomarker for the early stages of osteoarthritis.

BACKGROUND: Clinical tools to diagnose the early changes of osteoarthritis (OA) that occur in the articular cartilage are lacking. OBJECTIVES: We sought to identify and quantify a novel cartilage oligomeric matrix protein (COMP) neoepitope in the synovial fluid from the joints of healthy horses and those with different stages of OA. STUDY DESIGN: In vitro quantitative proteomics and assay development with application in synovial fluids samples obtained from biobanks of well-characterised horses. METHODS: Articular cartilage explants were incubated with or without interleukin-1ß for 25 days. Media were analysed via quantitative proteomics. Synovial fluid was obtained from either normal joints (n = 15) or joints causing lameness (n = 17) or with structural OA lesions (n = 7) and analysed for concentrations of the COMP neoepitope using a custom-developed inhibition enzyme-linked immunosorbent assay (ELISA). Explants were immunostained with polyclonal antibodies against COMP and the COMP neoepitopes. RESULTS: Semitryptic COMP peptides were identified and quantified in cell culture media from cartilage explants. A rabbit polyclonal antibody was raised against the neoepitope of the N-terminal portion of one COMP fragment (sequence SGPTHEGVC). An inhibition ELISA was developed to quantify the COMP neoepitope in synovial fluid. The mean concentration of the COMP neoepitope significantly increased in the synovial fluid from the joints responsible for acute lameness compared with normal joints and the joints of chronically lame horses and in joints with chronic structural OA. Immunolabelling for the COMP neoepitope revealed a pericellular staining in the interleukin-1ß-stimulated explants. MAIN LIMITATIONS: The ELISA is based on polyclonal antisera rather than a monoclonal antibody. CONCLUSIONS: The increase in the COMP neoepitope in the synovial fluid from horses with acute lameness suggests that this neoepitope has the potential to be a unique candidate biomarker for the early molecular changes in articular cartilage associated with OA.

Characterisation of lubricin in synovial fluid from horses with osteoarthritis.

REASON FOR PERFORMING STUDY: The glycoprotein lubricin contributes to the boundary lubrication of the articular cartilage surface. The early events of osteoarthritis involve the superficial layer where lubricin is synthesised. OBJECTIVES: To characterise the glycosylation profile of lubricin in synovial fluid from horses with osteoarthritis and study secretion and degradation of lubricin in an in vitro inflammation cartilage model. STUDY DESIGN: In vitro study. METHODS: Synovial fluid samples collected from horses with joints with normal articular cartilage and structural osteoarthritic lesions; with and without osteochondral fragments, were analysed for the lubricin glycosylation profiles. Articular cartilage explants were stimulated with or without interleukin-1ß for 25 days. Media samples collected at 3-day intervals were analysed by quantitative proteomics, western blot and enzyme-linked immunosorbent assay. RESULTS: O-glycosylation profiles in synovial fluid revealed both Core 1 and 2 O-glycans, with Core 1 O-glycans predominating. Synovial fluid from normal joints (49.5 ± 1.9%) contained significantly lower amounts of monosialylated Core 1 O-glycans compared with joints with osteoarthritis (53.8 ± 7.8%, P = 0.03) or joints with osteochondral fragments (57.3 ± 8.8%, P = 0.001). Additionally, synovial fluid from normal joints (26.7 ± 6.7%) showed higher amounts of disialylated Core 1 O-glycan than from joints with osteochondral fragments (21.2 ± 4.9%, P = 0.03). A C-terminal proteolytic cleavage site in lubricin was found in synovial fluid from normal and osteochondral fragment joints and in media from interleukin-1ß stimulated and unstimulated articular cartilage explants. CONCLUSIONS: This is the first demonstration of a change in the glycosylation profile of lubricin in synovial fluid from diseased equine joints compared with that from normal joints. We demonstrate an identical proteolytic cleavage site of lubricin both in vitro and in vivo. The reduced sialation of lubricin in synovial fluid from diseased joints may affect the boundary lubricating ability of the superficial layer of articular cartilage and could be one of the early events in the progression of osteoarthritis.

Indications of that migration of stem cells is influenced by the extra cellular matrix architecture in the mammalian intervertebral disk region.

Disk-degeneration is believed a major cause for lumbar pain. Previously, potential stem cell niches in the intervertebral disk (IVD) region, located adjacent to epiphyseal plate, was reported. The aim of the study was to examine migration of mesenchymal stem cells (MSCs), extracellular matrix (ECM) architecture in a potential cellular migration route (CMR; area located between the niche and IVD) and in the IVD in non-degenerated lapine- and in human degenerated IVD tissues. Human MSCs (n=3), human degenerated IVD tissues (n=10) and lapine IVDs (n=10) were collected. The samples were examined by immunohistochemistry for stem cell markers; CD90, OCT3/4, pre-chondrocytic marker; GDF5, catabolic markers; MMP9, MMP13, inflammatory marker; IL1R, cellular migration markers; SNAI1, SNAI2, adhesion markers; ß1-INTEGRIN and DDR2. In addition, gene-expression analyses (Real time PCR) were performed on additional samples. Further, time lapse studies were performed with hMSCs cultured on aligned COLL-I-fibers-coated glass-slides in DMEM-LG, 10% human serum containing fibroblast growth factor (bFGF). Presence of stem cells (CD90+, OCT3/4+), pre-chondocytic cells (GDF5+) and cells positive for migration markers (SNAI1+, SNAI2+), catabolic markers (MMP9+, MMP13+), inflammatory marker (IL1R+), adhesion markers (DDR2+, B1-INTEGRIN+) were detected (gene- and protein level) in investigated CMR and IVD regions. In the time lapse studies, MSCs alignment and protrusions were observed orientated in the same direction as collagen fibers. Results display influence of ECM collagen architecture and collagen fiber spatial direction on migration of stem cells. The results can be useful when developing tissue-engineering strategies for disk-degeneration.

Ultrastructural immunolocalization of cartilage oligomeric matrix protein (COMP) in the articular cartilage on the equine third carpal bone in trained and untrained horses.

The present study was designed to delineate the presence of COMP at the ultrastructural level comparing concentrations between two areas of articular cartilage from the equine third carpal bone, subjected to different loading, from trained and untrained horses. We also analyzed the fibril thickness of collagen type II in the same compartments and zones. Samples were collected from high load-bearing areas of the dorsal radial facet (intermittent high load) and an area of the palmar condyle (low constant load) in five non-trained and three trained young racehorses. The data show that COMP is much less abundant in the matrix in intermittent high loaded areas of articular cartilage from trained horses as compared to the untrained horses (p=0.036). On the other hand, the untrained horses often displayed a higher immunolabeling in loaded areas compared to unloaded areas, indicating that an adequate dynamic load promotes COMP synthesis and/or retention, while an excessive load may have an opposite effect. The collagen fibril diameter showed marked variation between individuals. The present study indicates that dynamic in vivo compression at high load and frequency lowers matrix content of COMP in the articular cartilage of the third carpal bone. It also indicates that the collagen network is influenced by mechanical load following by strenuous exercise.

Altered homeostasis of extracellular matrix proteins in joints of standardbred trotters during a long-term training programme.

This study evaluates how strenuous training, age and lameness influence the release of cartilage oligomeric matrix protein (sf-COMP), aggrecan and collagen type II into synovial fluid in 28 (19.5-40 months) Standardbred trotters (STB), during a long-term training programme (24 months). All the horses were trained by the same trainer and were healthy on entering the training programme. Synovial fluid (sf) from the left middle carpal joint in each subject was sampled every third month. Enzyme-linked immunosorbent assay was used to determine the concentrations of sf-COMP, sf-aggrecan and sf-collagen type II. Concentration of sf-COMP decreased with increasing age and total days of training. The concentration of sf-COMP was found similarly related to both age and total days of training, so they could not be differentiated. It was also shown that the concentration of collagen type II degradation products increased with total days of training. The study shows that extensive and long-term training programme induces metabolic changes in articular cartilage exemplified by reduced release and synthesis of COMP. This is most likely due to strenuous training leading to inappropriate load on the articular cartilage.

Ultrastructural immunolocalisation of bone sialoprotein in the osteocartilagenous interface of the equine third carpal bone.

REASONS FOR PERFORMING STUDY: One of the most common causes of lameness in racehorses is osteoarthritis (OA). Pathogenesis is not clear and pathological processes of the different joint tissues interact in often progressive events. The interface between cartilage and newly synthesised bone has been shown to be particularly enriched in bone sialoprotein (BSP), a cell-binding matrix protein. OBJECTIVES: To establish whether changes in the concentration of BSP may serve as a marker for early biochemical changes of the subchondral bone. METHODS: Articular cartilage, cartilage/bone interface and subchondral bone of the proximal third carpal bone from 3 Standardbred trotters were analysed ultrastructurally for the presence of BSP in normal and degenerative areas. RESULTS: A marked increase of BSP in the cartilage/bone interface with degenerative changes of the bone and cartilage compared to the morphologically intact cartilage/bone interface was noted, but levels of the protein were distinctly lower in the distal bone. CONCLUSIONS: The results indicate that BSP has the potential to be used as a marker for changes in bone metabolism in the subchondral bone. POTENTIAL RELEVANCE: Tools to monitor early biochemical changes within the connective tissues of the joint in vivo are essential in studies of the pathogenesis of OA. These could be used to monitor and understand such changes in relation to load, exercise, training programmes, inflammation and the development of OA.

Enhanced concentration of COMP (cartilage oligomeric matrix protein) in osteochondral fractures from racing Thoroughbreds.

The aim of the present study was to correlate the levels of COMP and aggrecan as indicators of tissue damage, in synovial fluid (sf) from carpal joints of acutely lame racehorses, with macroscopical lesions of articular cartilage (OA), osteochondral fractures and ligament tears found at arthroscopy. Sixty-three lame horses [49 Standardbred trotters (STB) and 14 Thoroughbreds (TB)] in conventional training and racing that underwent arthroscopy of their middle carpal or radiocarpal joints were included in the study. Intact as well as fragmented COMP and aggrecan released into the synovial fluid were quantified by western blot analyses and ELISA. The expression of COMP in tissues was estimated by mRNA in situ hybridisation and protein immunolocalisation in cartilage and osteochondral fractures. The concentration of sf-COMP was higher in TB with an osteochondral fracture than in STB with osteochondral fractures and TB and STB with OA. The chondrocytes in middle and deep zones of the articular cartilage of the osteochondral fragments (from a TB) expressed COMP mRNA, in contrast to the cartilage on the opposite side of the fracture where no expression was detected. In the synovial fluid from a joint (TB) with osteochondral fractures only intact COMP was present, whereas, fragmented COMP was more prominent in synovial fluid from a joint with OA. The concentration of sf-aggrecan did not differ between the two breeds, or between different lesions. The increased concentration of sf-COMP in TB with osteochondral fractures, but not in synovial fluid from equine joints with OA, is a novel finding. The results from this study indicate that elevated sf-COMP concentration in the joints of Thoroughbreds may be a useful marker for carpal joint osteochondral fragments.

Ex vivo magnetic resonance imaging of the distal row of equine carpal bones: assessment of bone sclerosis and cartilage damage.

The distal row of carpal bones (C2, C3, and C4) from eight left intercarpal joints--four from Standardbred Trotters and four from Swedish Warmblood horses--were used to assess the potential of magnetic resonance (MR) imaging to detect cartilage and bone lesions. The joints used in the study were classified by macroscopic and radiographic examinations as having normal, mild, moderate, or severe articular cartilage lesions and bone sclerosis. Those classifications correlated well with the appearance of the MR images. Bone sclerosis in the MR images was observed as regions of decreased signal intensity. Upon quantitative analysis of the MR images there was a significant difference (p < 0.0001) in the MR signal intensity from areas where radiographic bone sclerosis was observed compared to areas of radiographic nonsclerotic bone. In addition, the MR images were used to pilot the location of histology slices through areas of interest that were then examined microscopically; hence, the lesions found from the MR imaging examination were verified microscopically. It was concluded that cartilage lesions and cartilage loss are related to the sclerotic state of the underlying bone. The MR protocols developed in this study were applied on five intact cadaveric carpal joints, and it was concluded that MR imaging could successfully be used in the intact joint to detect minor cartilage and bone lesions not visualized by either radiography or macroscopic examination. Hence, MR imaging can be used to delineate interactions between articular cartilage and subchondral bone over time and in vivo.

Concentration of collagen, aggrecan and cartilage oligomeric matrix protein (COMP) in synovial fluid from equine middle carpal joints.

The aim of the present investigation was to study the metabolic activity of the third carpal bone and the release of COMP, aggrecan and collagen type II molecules in the synovial fluid as a result of injury. Cartilage oligomeric matrix protein (COMP), aggrecan and collagen type II or fragments of these molecules released to the synovial fluid and serum (COMP) were quantified in samples from 73 left equine middle carpal joints from 2 breeds with different activity profiles (52 Standardbred trotters [STB] and 21 Swedish Warmblood riding horses [SWH]) and different articular cartilage lesions. Synovial and serum samples were analysed using inhibition ELISA for COMP and aggrecan. An ELISA that combines features of both the competitive and capture ELISAs was used for collagen type II. COMP and aggrecan concentrations decreased in synovial fluid from the joints with moderate lesions of STB compared with the normal joints; COMP from 16.6 to 12.0 microg/ml and aggrecan from 93.0 to 68.1 microg/ml. In serum, COMP concentrations were also lowered in the STB with moderate lesions compared with the normal joints, while in the SWH, the COMP concentration in synovial fluids from joints with moderate lesions was somewhat increased at 19.6 microg/ml compared with the normal joints (17.6 microg/ml). The ratio between aggrecan/COMP in the synovial fluid from joints with moderate lesions was higher in the STB (6.2) than in the SWH (3.4). The level of collagen type II in synovial fluid was higher in the SWH (8.8 microg/ml) than the STB (1.6 microg/ml), but there was no correlation between joint damage and collagen concentrations in synovial fluids (10.0 and 1.8 microg/ml in joints with moderate lesions from SWH and STB, respectively). A marked difference in COMP synthesised upon metabolic labelling between the normal and osteoarthritic cartilage was seen and the synthesis of COMP in the articular cartilage of the third carpal bone with moderate articular lesions (from an STB) was lower than in the joint with mild lesions. This difference between breeds may reflect different load characters, in release of macromolecules in osteoarthritic and normal joints. This a novel finding that should be considered in studies of equine traumatic arthritis.

The acute phase protein serum amyloid A (SAA) as an inflammatory marker in equine influenza virus infection.

The acute phase protein serum amyloid A (SAA) has proven potentially useful as an inflammatory marker in the horse, but the knowledge of SAA responses in viral diseases is limited. The aim of this study was to evaluate SAA as a marker for acute equine influenza A2 (H3N8) virus infection. This is a highly contagious, serious condition that inflicts suffering on affected horses and predisposes them to secondary bacterial infections and impaired performance. Seventy horses, suffering from equine influenza, as verified by clinical signs and seroconversion, were sampled in the acute (the first 48 h) and convalescent (days 11-22) stages of the disease, and SAA concentrations were determined. Clinical signs and rectal temperature were recorded. Secondary infections, that could have influenced SAA concentrations, were clinically suspected in 4 horses. SAA concentrations were higher in the acute stage than in the convalescent stage, and there was a statistically positive relationship between acute stage SAA concentrations and clinical signs and between acute stage SAA concentrations and maximal rectal temperature. Horses sampled early in the acute stage had lower SAA concentrations than those sampled later, indicating increasing concentrations during the first 48 h. There was a statistically positive relationship between convalescent SAA concentrations and degree of clinical signs during the disease process. The results of this investigation indicate that equine SAA responds to equine influenza infection by increasing in concentration during the first 48 h of clinical signs and returning to baseline within 11-22 days in uncomplicated cases.