OBJECTIVE To use proteomic analysis to determine the protein constituents of synovial fluid samples from the stifle joints of dogs with and without osteoarthritis secondary to cranial cruciate ligament rupture (CCLR). ANIMALS 12 dogs with clinically normal stifle joints (controls) and 16 dogs with osteoarthritis secondary to CCLR. PROCEDURES A synovial fluid sample was obtained from all dogs. Synovial fluid total protein concentration was determined by the Bradford assay. Proteins were separated by use of a 1-D SDS-PAGE to detect protein bands that differed between dogs with and without osteoarthritis. Those protein bands then underwent trypsin digestion and were analyzed by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry, the results of which were compared with a curated protein sequence database for protein identification. One of the most frequently identified proteins, apoprotein (apo) A-I, was then quantified in all synovial fluid samples by use of a competitive-inhibition ELISA. Results were compared between dogs with and without osteoarthritis. RESULTS Median synovial fluid total protein and apo A-I concentrations for dogs with osteoarthritis were significantly greater than those for control dogs. The most abundant proteins identified in the synovial fluid were albumin and apo A-I. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that quantification of synovial fluid total protein and apo A-I concentrations might facilitate diagnosis of osteoarthritis secondary to CCLR in dogs. Further research and validation of synovial fluid apo A-I concentration as a biomarker for osteoarthritis in dogs are necessary before it can be recommended for clinical use.

Objective: To determine the expression and distribution of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), its substrates aggrecan and versican, and their binding partner hyaluronan in laminae of healthy horses. Sample: Laminae from the forelimb hooves of 8 healthy horses. Procedures: Real-time quantitative PCR assay was used for gene expression analysis. Hyaluronidase, chondroitinase, and keratanase digestion of lamina extracts combined with SDS-PAGE and western blotting were used for protein and proteoglycan analysis. Immunofluorescent and immunohistochemical staining of tissue sections were used for protein and hyaluronan localization. Results: Genes encoding ADAMTS-4, aggrecan, versican, and hyaluronan synthase II were expressed in laminae. The ADAMTS-4 was predominantly evident as a 51-kDa protein bearing a catalytic site neoepitope indicative of active enzyme and in situ activity, which was confirmed by the presence of aggrecan and versican fragments bearing ADAMTS-4 cleavage neoepitopes in laminar protein extracts. Aggrecan, versican, and hyaluronan were localized to basal epithelial cells within the secondary epidermal laminae. The ADAMTS-4 localized to these cells but was also present in some cells in the dermal laminae. Conclusions and Clinical Relevance: Within digital laminae, versican exclusively and aggrecan primarily localized within basal epithelial cells and both were constitutively cleaved by ADAMTS-4, which therefore contributed to their turnover. On the basis of known properties of these proteoglycans, it is possible that they can protect the basal epithelial cells of horses from biomechanical and concussive stress.

The purpose of this study was to determine the relationship between the serum level of C-reactive protein (CRP) and lactation and health status. Blood samples were collected every 2 wk for 12 mo from 29 randomly selected dairy cattle on 3 farms. At the time the blood samples were collected, the stage of pregnancy, lactation status, breeding records, general health condition, reproductive status, and body condition score were recorded for each cow. Serum CRP was detected with sodium dodecyl sulfate polyacrylamide gel electrophoresis and western immunoblotting. C-reactive protein levels were measured with a densitometer and expressed as an optimal dose value. C-reactive protein levels were correlated with the body condition score, lactation status, and animal health (P < 0.05), but not with ambient temperature, animal age, or parity. C-reactive protein levels increased with milk production, peaking during high lactation (2 to 4 mo of pregnancy), and decreased when lactation ceased. In addition, the CRP level was highest during naturally occurring infections, such as mastitis and other tissue inflammation. Thus, the CRP level can confirm the presence of inflammation. The stress effect of taking blood samples as measured by the CRP level, was also examined. The CRP level became rapidly elevated 12 h after the blood samples were taken but returned to normal 36 h later. In conclusion, the stresses resulting from overall poor health, heavy lactation, and blood sampling caused the elevation of serum CRP. C-reactive protein is a marker or tool for evaluating the health status of a herd. C-reactive protein should also be considered as a useful criteria to assess the stress levels and may be useful in early surveillance of disease conditions in a dairy herd.

High-intensity exercise can be associated with the occurrence of muscle injury, as well as the induction of an acute-phase response (APR). The present study aims to investigate the synthesis and profile of serum proteins in horses before and after participating in 2 different exercise protocols and to relate this profile to the presence or absence of muscular injury caused by exercise. Ten purebred Arabian (n = 5) and Criollo (n = 5) horses were subjected to 2 different tests on a treadmill, one consisting of short-duration and rapid-acceleration training (TRA) that was mostly anerobic and the other of long-duration and slow-acceleration training (TLD) that was predominantly aerobic. Blood samples were obtained before the beginning of exercise (T0) and at 6 post-exercise time points: immediately after (T1) and 30 min (T2), 3 h (T3), 12 h (T4), 24 h (T5), and 48 h (T6) after exercise. Hematocrit was determined by the microhematocrit method. Plasma and serum samples were prepared by centrifugation (1500 × g for 5 min) for plasma concentrations of fibrinogen, total serum proteins (TP), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and creatine-kinase (CK) serum activity. Total protein concentration and CK serum activity were determined in an automated biochemistry analyzer. Fibrinogen was determined by the heat precipitation method in microhematocrit capillary tubes. Estimated concentrations of haptoglobin (Hp) significantly decreased after TRA and estimated concentrations of alpha-1 acid glycoprotein (AGP) significantly increased after both protocols at T2. Albumin increased after the TLD exercise protocol. Changes in hematocrit, haptoglobin, and albumin concentrations in horses subjected to different treadmill exercise protocols are related to a physiological response to hemoconcentration and hemolysis. Increases of AGP in the TLD protocol suggest the release of catecholamines as a response to avoid oxidative damage to tissue.

Objective—To examine the changes in monocarboxylate transporter (MCT) 1 and MCT4 content and in indicators of energy metabolism in the gluteus medius muscle (GMM) of Thoroughbreds during growth. Animals—6 Thoroughbreds (3 males and 3 females). Procedures—Samples of GMM were obtained when horses were 2, 6, 12, and 24 months old. Muscle proteins were separated via SDS-PAGE; amounts of MCT1 and MCT4 and peroxisome proliferator-activated receptor-γ coactivator-1α content were determined by use of western blotting. Muscle activities of phosphofructokinase and citrate synthase were measured biochemically; lactate dehydrogenase isoenzymes were separated by agarose gel electrophoresis and quantified. Results—Compared with findings when horses were 2 months old, MCT1 protein content in GMM samples obtained when the horses were 24 months old was significantly higher; however, MCT4 protein content remained unchanged throughout the study period. Peroxisome proliferator-activated receptor-γ coactivator-1α content was significantly increased at 24 months of age and citrate synthase activity was increased at 6 and 24 months of age, compared with findings at 2 months. Phosphofructokinase activity remained unaltered during growth. The percentage contributions of lactate dehydrogenase 1 and 2 isoenzymes to the total amount of all 5 isoenzymes at 12 and 24 months of age were significantly higher than those at 2 months of age. Conclusions and Clinical Relevance—Changes in protein contents of MCTs and the lactate dehydrogenase isoenzyme profile in GMM samples suggested that lactate usage capacity increases with growth and is accompanied by an increase in the oxidative capacity in Thoroughbreds.

Objective: To determine whether increased gene expression of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) in laminae of horses with starch gruel–induced laminitis was accompanied by increased enzyme activity and substrate degradation. Sample: Laminae from the forelimb hooves of 8 healthy horses and 17 horses with starch gruel–induced laminitis (6 at onset of fever, 6 at onset of Obel grade 1 lameness, and 5 at onset of Obel grade 3 lameness). Procedures: Gene expression was determined by use of cDNA and real-time quantitative PCR assay. Protein expression and processing were determined via SDS-PAGE and quantitative western blotting. Protein distribution and abundance were determined via quantitative immunofluorescent staining. Results: ADAMTS-4 gene expression was increased and that of versican decreased in laminitic laminae, compared with expression in healthy laminae. Catalytically active ADAMTS-4 also was increased in the tissue, as were ADAMTS-4–cleavage fragments of versican. Immunofluorescent analyses indicated that versican was depleted from the basal epithelia of laminae of horses at onset of Obel grade 3 lameness, compared with results for healthy laminae, and this was accompanied by regional separation of basal epithelial cells from the basement membrane. Aggrecan gene and protein expression were not significantly affected. Conclusions and Clinical Relevance: Changes in gene and protein expression of ADAMTS-4 and versican in the basal epithelium of laminitic laminae indicated a fundamental change in the physiology of basal epithelial cells. This was accompanied by and may have caused detachment of these cells from the basement membrane.

Objective-To evaluate lactoferrin and lysozyme content in various ocular glands of bison and cattle and in tears of bison. Sample Population-Tissues of ocular glands obtained from 15 bison and 15 cattle and tears collected from 38 bison. Procedure-Immunohistochemical analysis was used to detect lysozyme and lactoferrin in formalin-fixed, paraffin-embedded sections of the ocular glands. Protein gel electrophoresis was used to analyze ocular glands and pooled bison tears by use of a tris-glycine gel and SDS-PAGE. Western blotting was used to detect lactoferrin and lysozyme. Results-Immunohistochemical staining for lactoferrin was evident in the lacrimal gland and gland of the third eyelid in cattle and bison and the deep gland of the third eyelid (Harder's gland) in cattle. Equivocal staining for lactoferrin was seen for the Harder's gland in bison. An 80-kd band (lactoferrin) was detected via electrophoresis and western blots in the lacrimal gland and gland of the third eyelid in cattle and bison, Harder's glands of cattle, and bison tears. An inconsistent band was seen in Harder's glands of bison. Lysozyme was not detected in the lacrimal gland of cattle or bison with the use of immunohistochemical analysis or western blots. Western blots of bison tears did not reveal lysozyme. Conclusion and Clinical Relevance-Distribution of lactoferrin and a lack of lysozyme are similar in the lacrimal gland of cattle and bison. Differences in other tear components may be responsible for variability in the susceptibility to infectious corneal diseases that exists between bison and cattle.