Which needle is most appropriate for sampling spinal fluid in a 30 kg Labrador?

Which needle is most appropriate for sampling spinal fluid in a 30 kg Labrador?

• A. 21 gauge 1.5 inch
• B. 22 gauge 1 inch
• C. 23 gauge 1.0 inch
• D. 20 gauge 2 inch

Answer: (A)

Sampling cerebrospinal fluid in a large dog relies on using a spinal needle that can reach the intrathecal space without causing excess tissue trauma. For a 30 kg Labrador, a 21-gauge needle about 1.5 inches long provides the right balance: long enough to reach the subarachnoid space from the lumbosacral area, and with a bore size that allows smooth CSF withdrawal without being overly large. A shorter needle might fail to access the space, a finer needle (higher gauge) can clog or slow flow, and a larger bore with extra length increases tissue trauma and the risk of post-puncture complications.

Sampling cerebrospinal fluid in a large dog relies on using a spinal needle that can reach the intrathecal space without causing excess tissue trauma. For a 30 kg Labrador, a 21-gauge needle about 1.5 inches long provides the right balance: long enough to reach the subarachnoid space from the lumbosacral area, and with a bore size that allows smooth CSF withdrawal without being overly large. A shorter needle might fail to access the space, a finer needle (higher gauge) can clog or slow flow, and a larger bore with extra length increases tissue trauma and the risk of post-puncture complications.