Ask the Vet

Smaller-Gauge Needles Best for Most Jobs

Needle size and proper vaccination protocol are key in Beef Quality Assurance. (DTN/Progressive Farmer file photo by Jim Patrico)


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).

Regarding needle size, I recommend the smallest-gauge needle possible. Large needles make bigger holes, are more painful, 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, a 16-gauge, I prefer a 3/4-inch needle. I only use needles once. This means they are sharper when you use them, and it also eliminates any risk of spreading a disease like anaplasmosis in the herd.

For intramuscular injections, I recommend an 18-gauge, 1-inch to 1 1/2- inch needle. If product is very thick, I may use a 16-guage needle, but I find very little need for this size now with products currently on the market.

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 (

Another key to good injection technique, and something covered in a BQA program, is proper restraint. You'll also cover things like why you never inject more than 10 ml at one site and why you never inject though a dirty hide. If you don't use a clean needle every time, BQA protocol says change them out at least every 10 head. But do use a clean needle every time you pull up vaccine or medication from the bottle. Never use bent or burred needles.

I know this is a lot, but the point I'd leave you with is: Needles are cheap, cows are not.


Editor's Note:

Please contact your veterinarian with questions pertaining to the health of your herd or other animals. Every operation is unique, and the information in this column does not pertain to all situations. This is not intended as medical advice but is purely for informational purposes.

Write Dr. Ken McMillan at Ask the Vet, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email