Medi-Dart needle/valve assembly with wingnut #5 (MDAKW5)

Details

Treating an animal at grass means the outfit has to be working when you get there, not after a trip back to the shop for one missing part. This assembly is put together with that in mind: the #5 needle, the valve components it seats against, and the plastic wingnut, all in one package. The wingnut is what most people are actually short of. It works with the needle and the push rod to lift the needle back out of the animal once the barrel has emptied, and Medi-Dart makes it in two sizes. The 13 mm (1/2 in) suits cows and bulls, while the 9.5 mm (3/8 in) is the one for younger cattle up to yearlings. Match the size to the class you are treating rather than to the needle. The #5 is a rough-ridge grade and the needle most crossbow kits were originally supplied with. It runs without the half-moon push rod, which makes this assembly a sensible choice for an older dart you would rather not convert. If you are moving to the #6 instead, that needle does need the half-moon rod. These are reusable parts, not consumables, and the needle can be taken back with a file when the point dulls. Keep an o-ring or two on hand, since that is the part that fails first and quietly. Treatment decisions stay with your veterinarian and the label.