Characteristics of normal equine tarsal synovial fluid.

This study investigates the physical, biochemical, and cytological properties of the synovial fluid found in normal horse tarsal joints. It simplifies the understanding of its characteristics, shedding light on its physical appearance, volume, viscosity, tests for several enzymes, and the presence of cells types.

Physical Properties

• The synovial fluid was said to be pale yellow in color, clear, and neither clumped nor clotting occurred.
• The volume was found to be directly proportional to the size of the tarsal joint, implying larger joints would produce more synovial fluid.

Biochemical Properties

• An important characteristic of the fluid was its viscoelastic property, this was found to be related to the amount and polymerization state of hyaluronic acid – a substance that gives the fluid its lubricating properties – and its protein concentration.
• Also, the quality of the mucinous precipitate (hyaluronic acid after polymerization) was said to be high.
• When it came to proteins, the concentration of proteins in synovial fluid was indicated to be low which correlates with a high A:G ratio (ratio of albumin to globulin, types of proteins).
• The balance between sugar content in serum (liquid part of blood) and synovial fluid was found to be 1.24:1.
• A series of enzymes including ALP (Alkaline Phosphatase), ACP (Acid Phosphatase), LDH (Lactate Dehydrogenase), GOT (Glutamic-oxaloacetic transaminase), and GPT (Glutamate Pyruvate Transaminase) were all shown to have higher activity levels in serum than in synovial fluid. However, ALD (Aldehyde Dehydrogenases) activity was slightly lower in serum than in tarsal synovial fluid.

Cytological Properties

• The study also found a noticeable variability in total erythrocyte (red blood cell) counts, while leukocyte (white blood cell) counts were relatively uniform and low.
• When looking at cell types, lymphocytes – a type of white blood cell – were the predominant cells in the synovial fluid.