Ask the Vet

Needle Size Matters

The best needle to use, depends on the job and the animal. The most important tip: use a clean needle every time. (DTN/Progressive Farmer photo)


What size needle do you recommend for giving cows shots?


To some degree, this depends on where you are giving the injection and what it is. Start with placement. Injections should always be given in the neck. If so labeled, they should be given under the skin, or subcutaneously (SQ).

Concerning needle size, I recommend the smallest gauge needle possible. Large needles make bigger holes, are more painful and cause more damage, and product can leak back out. I use 20-gauge, 3/4-inch needles for SQ vaccinations on calves. With adult cattle, or when administering thick medications, I use a 16-gauge with a 3/4-inch needle. I only use needles once. This means they are sharper when you use them, and it eliminates any risk of spreading disease in the herd. For intramuscular injections, I recommend an 18-gauge, 1-to-1-1/2-inch needle. If the product is very thick, I may use a 16-gauge needle, but I find very little need for this size now with products currently on the market.

Another key to good injection technique is proper restraint. Never inject more than 10 milliliters at one site, and never inject through a dirty hide. If you don't use a clean needle every time, change them out at least every 10 head. A clean needle is critical every time you pull up vaccine or medication. Never use bent or burred needles. At the end of the day, my motto is "needles are cheap; cows are not."

If you have not done this already, I highly recommend becoming Beef Quality Assurance (BQA) certified. Needle size and proper vaccination protocol is a big part of the training. BQA saves the cattle industry millions, if not billions, of dollars through reduced damage to valuable cuts of meat. It also helps reduce the incidence of disease. Most states have BQA meetings where you can become certified, and there is an online program, as well (