Arthrocentesis in dogs and cats: indications and technique
Which statement about arthrocentesis is correct?
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A. It is not recommended in cats, because their joints are too small
With fine needles it can be performed in cats just as in small dogs, and it is essential to diagnose feline polyarthritis or septic arthritis.
B. Use a large needle (18 G) and aspirate hard to obtain at least 2–3 mL
Small joints yield only a few drops. A large needle and strong suction increase the risk of damaging cartilage and contaminating the sample with blood.
C. With a fine needle and aseptic technique, a few drops are enough for a direct smear; if infection is suspected, culture in a blood culture bottle
Correct. With 22–25 G needles and a small syringe, prioritise an immediate smear (also assess viscosity). Blood culture bottles improve bacterial recovery compared with direct culture of the fluid.
D. It is contraindicated if septic arthritis is suspected, because it may spread infection
Suspected septic arthritis is precisely a clear indication. The contraindication is puncturing through infected skin or cellulitis.
lightbulb Key takeaway
Indications: joint effusion, suspected septic arthritis or polyarthritis, fever of unknown origin and shifting lameness. Clip and prepare the skin as for surgery, enter with the joint positioned to open the joint space, and release suction before withdrawing the needle to avoid blood contamination.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.