Biochemical markers and radiographic scores as an evaluation for the osteoarticular status of Warmblood stallions.

Establishing the osteoarticular status of the horse is often performed by means of radiological screening of the animals. Widespread blood sampling could potentially be an alternative to this procedure which is time consuming and sometimes technically difficult. The aim of this study was to investigate the relationship between the radiological status of the horses and the levels of biochemical markers (BM) of cartilage degradation and synovial inflammation. Materials and Methods: A specific radiological scoring (RS) system was developed and applied on 63 stallions presented for studbook admission. Additionally, groups of horses were established according to the occurrence of osteochondrosis (OC), degenerative joint disease (DJD) and distal interphalangeal joint (DIPJ) effusion. Insulin growth factor-I, myeloperoxidases, Coll2-1 and Coll2-1NO2 were used as BM. The effects of age and weight on the BM and of the BM on the RS were measured. Mean values of BM between OC positive versus negative, DJD positive versus negative and DIPJ effusion positive versus negative were compared using SAS statistical program. Results: No effect of the combined BM was found on the RS. No significant differences between the values of the BM were found within the different radiological classes (RC). However, considering only the Coll2-1NO2 marker, the probability to belong to class A was given by the equation 9.63 -0.31 Coll2-1NO2 + 0.04 (Coll2-1NO2)². Equally a tendency (p= 0.06) towards an increase in RC by 0.45 for each increasing unit of Coll2-1NO2 was present. Significant positive correlations were found between Coll2-1 values and Coll2-1 NO2 values. MPO values were found to be significantly higher in OC negative horses (357.86  64.43 ng/ml) than in OC positive horses (231.17  27.15 ng/ml). IGF-I levels were found significantly lower in the positive DIPJ effusion group (416.05  17.57 ng/ml) compared to the negative DIPJ effusion group (477.1  22.40 ng/ml). Coll2-1 values were significantly higher in the positive DIPJ effusion group (911.04  41.13 nM) compared to the negative DIPJ effusion group (769.04  37.92 nM). Mean values of Coll2-1 were significantly higher in the DJD positive group (901.24  36.75 nM) compared to the DJD negative group (790.590  39.397 nM) Discussion: The combination of the blood parameters did not seem to correlate with the used RS system. Coll2-1NO2 levels however tend to increase with poorer RC and could therefore be used as a useful predictor of the osteoarticular status of the horse. Coll2-1 levels were significantly higher in the degenerative joint disease group. A high percentage of horses with DIPJ effusion was present in this study and was associated with decreased IGF-I and increased Coll2-1 levels.