Evaluation of a canine Coll2-1 ELISA kit for use in equine serum and its correlation with radiographic joint disease.

Overview

• This study investigated whether a blood test designed to detect a cartilage breakdown product (Coll2-1) in dogs could be applied to horses and if the test results correlate with joint damage visible on X-rays.
• The test showed reliable analytic performance in horse serum but did not correlate with X-ray evidence of osteoarthritis in the horses studied.

Background and Objectives

• Osteoarthritis (OA) involves the degradation of cartilage in joints, releasing fragments of type II collagen such as Coll2-1 peptide into the bloodstream.
• Coll2-1 can be measured using an enzyme-linked immunosorbent assay (ELISA), which is commercially available for dogs.
• The study aimed to:
  • Assess if the canine Coll2-1 ELISA kit is analytically valid for measuring Coll2-1 in equine serum.
  • Determine if serum Coll2-1 levels correlate with radiographic (X-ray) scores of osteoarthritis severity in horses.

Methods

• Twelve Lusitano stallions were selected, matched by age and workload but with varying degrees of joint osteoarthritis determined by radiographs.
• Joint X-rays were taken of multiple limb joints (stifle, tarsi, fetlocks, distal limbs) and scored on a standardized 0 to 4 scale according to OA severity.
• Blood samples were collected from each horse at rest to analyze serum Coll2-1 levels using the canine ELISA kit.
• Analytical performance measures included:
  • Intra-assay precision (repeatability within the same test run)
  • Inter-assay precision (reproducibility across different runs)
  • Regression analyses to validate results
• Statistical analyses involved testing the distribution of data with the Shapiro-Wilk test, applying non-parametric tests where necessary, and evaluating correlations between Coll2-1 levels and radiographic scores using Kendall’s Tau-b correlation method.

Results

• The ELISA test showed acceptable analytical precision for equine serum:
  • Intra-assay coefficient of variation (CV) ranged from 5.6% to 19.3%.
  • Inter-assay CV ranged from 3.6% to 22%.
  • Regression analysis yielded a coefficient of determination (R²) of 0.94, indicating strong test linearity and accuracy.
  • All these parameters met the original manufacturer criteria for the canine assay.
• No statistically significant correlations were found between serum Coll2-1 concentrations and radiographic OA severity scores in the horses studied.

Conclusions and Implications

• The canine ELISA kit for Coll2-1 can reliably measure this collagen fragment in equine serum, demonstrating good analytical performance across multiple assays.
• However, in this horse population, serum Coll2-1 levels did not serve as a sensitive biomarker for osteoarthritis as judged by X-ray findings.
• This suggests that while the assay is technically applicable for horses, Coll2-1 in serum may not reflect joint disease severity measured by radiographs in horses or at least not under the conditions or OA stages studied.
• Future research may explore other biomarkers or different animal populations, or examine whether Coll2-1 relates to other disease forms or stages in horses.