Dairy cows are susceptible to clinical diseases during transition to lactation. Circulating exosomes originating from different tissues/cells can be used as biomarkers of diseases to enhance health and productivity of at-risk cows. We hypothesized that during early lactation, circulating exosomes derived from cows at high-risk for diseases contain proteins that are different from exosomes derived from cows at low-risk for diseases. The high-risk group (n=20) was defined as those cows with the greatest concentrations of blood beta-hydroxybutyrate and non-esterified fatty acid on day 7 (d7) and d14 after calving and liver triacylglycerol on d 10, while the low-risk group (n=20) were those with the least concentrations of these metabolites. Exosomes were isolated from plasma collected on d10 from these high- and low-risk groups by coupling ultracentrifugation and size exclusion chromatography. The exosomes were characterized by immunoblotting, transition electron microscopy and nanoparticle tracking analysis. Proteomic profiling of these exosomes was examined using mass spectrometry. Our proteomic results revealed 139 bovine proteins in exosomes derived from cows at high-risk and cows at low-risk for diseases, of which 46 proteins were uniquely present in each group. Coiled-coil domain containing 88A, inhibin/activin β A chain and fibulin-1 were uniquely found in high-risk exosomes. These proteins are known to be involved in various diseases. The differences observed in exosomal content are preliminary evidence of a potential role for exosomes to be utilized in determining cows at risk for diseases during the transition period.