Page 350 - The Veterinary Care of the Horse

withdrawn with a sterile needle and syringe (Figure 8.4) and examined for the following.

• Appearance. Normal synovial fluid is clear and straw-coloured. Cloudiness is indicative
VetBooks.ir of acute inflammation or infection. Streaks of blood are likely to be due to bleeding

caused by the needle, but uniformly red synovial fluid is due to haemorrhage into the
joint caused by injury or infection.

• Viscosity. The synovial fluid from an inflamed joint is less viscous than normal synovial
fluid due to a reduction of hyaluronan.

• Cytology and protein concentration. The numbers of white blood cells and the protein

levels are elevated in an infected joint.

Figure 8.4 Synovial fluid is being withdrawn from this horse’s knee to see if the injury penetrated the joint capsule

Arthroscopy

The synovial membrane and the articular surfaces of some joints can be inspected with an

arthroscope (see page 118). This allows detection of lesions not yet visible on radiographs, as
well as examination of intra-articular ligaments and menisci.