Scooter's Supplies for Chronic Renal Failure (CRF)

About Needles

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Needles are sized in gauges, the same gauges that are used to size electric and other wires.  The lower the gauge, the bigger the diameter of the needle.  Most vets use Monoject 18 gauge needles to infuse cats and most cat owners use those same Monoject 18s in their first attempts at home infusion.  But most soon switch to Terumo 19 and 20 gauge needles because they seem to go in a little smoother than the Monojects and because their thin wall and ultra thin wall versions flow fluids faster than equivalently sized standard wall Monojects.  (The exception is the Monoject 19 gauge thin wall that has an equivalent flow rate to the Terumo 19s.)  Faster flow rates allow folks to switch to smaller needles and make smaller holes in their cats. Smaller holes mean a lesser chance of leakage after infusion and lesser long-term chance of scar tissue.







Radford Hunt, a member of the Feline CRF Support Group, actually ran flow tests on a variety of brands and sizes of needles - results are summarized below - for complete test results and methodology, click here.

Average Time to Flow 100 mL
All needles are 1" in length



Monoject 18


Terumo 18


Monoject 19 TW


Terumo 19 TW


Monoject 20


Terumo 20 UTW


Terumo 21 UTW


Monoject 22


Terumo 22 UTW


Terumo 23 UTW


Terumo 25 UTW


TW = Thin Wall    UTW = Ultra Thin Wall

David's Needle Advice for Newbies.  If you're buying your first box of needles for home infusion, I'd strongly suggest the Terumo 19s or 20s.  The 19s are preferable if you are infusing a lot of fluids and/or you have an inpatient cat.  The 20s are slower but they'll make a smaller hole in the cat.  I used both sizes for my Scooter Cat - the 20s when we were infusing less than 150 mL and the 19s for 150 mL or more.  The 19 gauge Monoject thin wall is also a reasonable choice.  It's as fast as the 19 gauge Terumo and Monoject packaging is superior to Terumo's.  Lots of folks have problems with the needle guards on the Terumos (I managed to stab myself twice), but the Monoject needle guards twist off easily.  But if you're using an IV set with a "luer lock" that holds the needle in place, the Terumo needle guards pull straight off easily.  See About IV Admin Sets above.  Last, if you have a very patient cat and  you're a calm, deliberate type yourself and you're infusing 100 mL or less per session, you might consider a Terumo UTW 21 or 22 gauge needle.  It will take 3-4 minutes or so to infuse 100 mL.  Prescriptions for needles are required if you live in CT, IL, MA, NJ, NY and RI.  But suppliers in other states, especially mail order suppliers, may insist on a prescription.  Check with the intended vendor prior to ordering.

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