EVALUATION OF VALIDITY OF SERUM MATRIX METALLOPROTEINASES 2 AND 3, SYNOVIAL FLUID INTEREUKIN 8, KERATYNOCYTE-DERIVED CHMOATTRACTANT AND MONOCYTE CHEMOATTRACTANT PROTEIN 1 AS BIOMARKERS OF STIFLE OSTEOARTHRITIS ASSOCIATED WITH NATURALLY OCCURRING CRANIAL CRUCIATE LIGAMENT RUPTURE IN DOGS