Sandra Corr, BVMS, CertSAS, Dipl. ECVS, FHEA, PhD, MRCVS
Sutton Bonington University, Nottingham, UK
Patient... Sedation is usually adequate, although to aspirate from the hip or shoulder joints, or if a joint is painful, heavy sedation or general anesthesia may be indicated.
Equipment... Set out microscope slides, an EDTA tube, a sterile plain tube or bottle of bacteriological culture medium, 2 and 5ml syringes, and some needles. Needle size and gauge will depend on the size of the joint and the depth of soft tissue that must be penetrated to access the joint. In most cases, 21-23g needles 5/8 - 11/2" long are suitable. In very large dogs, a longer spinal needle may be required for the hip and shoulder joints.
Preparation... Strict asepsis should be observed: clip and prepare the site routinely. Drapes are not necessary, but gloves should be worn to allow palpation of anatomical landmarks in a sterile manner.
Approach... Specific bony landmarks are used to approach each joint. The simplest and most commonly used approaches are described here, although alternatives exist. The needle should always be inserted gently, and carefully redirected if bone is hit, to minimize trauma to the articular cartilage. Flexing some joints will open up the joint spaces; note osteophytes may limit access to osteoarthritic joints. The easiest joints to sample are the carpus and stifle; the hock is the most difficult.
Synovial fluid analysis
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