Evaluation of creatine kinase and lactate dehydrogenase activities in clinically normal and abnormal equine joints.

The researchers carried out a study focusing on the activities of creatine kinase (CK) and lactate dehydrogenase (LD) enzymes, and their isoenzymes, in the joints of horses. They found that the enzyme activities varied widely and did not reliably predict the extent or type of joint damage in horses suffering from joint disease.

Isoenzyme Composition

• The investigation determined the amount and types of CK and LD isoenzymes found in the joint fluid, the synovial membrane (lining of the joints), and the articular cartilage (the protective cartilage at the ends of the bones) in healthy horses.
• Both CK and LD isotopes were found in all three tissues, but the MB isotype of CK was not present.
• However, due to the similarities in isoenzyme composition between these tissues, the scientists found it impossible to determine the original source of LD and CK isoenzymes simply based on their patterns.

Enzyme Activities in Healthy Tissues

• The researchers also established reference values for the overall enzyme activities of specific joint tissues in healthy horses.
• They found wide variations in activity, made evident through the enzymatic analysis of synovial fluid.
• Given the lack of tissue specificity and variations in enzyme activity, the scientists concluded that these measurements could not be used to predict the extent or type of tissue damage in horses with joint disease.

Study on Abnormal Joints

• This assumption was verified when the team of researchers analyzed synovial fluid from 22 abnormal joints for LD isoenzymes and total enzyme activity.
• The results confirmed their initial speculations as they could not differentiate between the various causes of the joint problems based on these values.

In conclusion, while CK and LD isoenzymes are present in equine joints, their activity levels seem to matter little in diagnosing or predicting joint diseases in horses. This suggests a need for more effective biomarkers for joint health in equine medicine.