Injecting Livestock

Most smallholders will need to inject livestock at some time. As well as antibiotics if an animal is unwell, there are routine vaccinations, injectable vitamins and minerals and injectable wormers.

Your vet is the best person to demonstrate correct techniques and can answer any queries you might have but the guide below will be a useful aide memoire.

Injection techniques

Injections are commonly given into the muscle (intramuscular), under the skin (subcutaneous) or into the bloodstream (intravenous).

The first two are relatively simple; the third requires a higher level of skill and care and should not be attempted without proper training as incorrect technique can result in the animal’s death.

There are other methods of injection, including intra-articular (into a joint) and epidural, but these must be left to your veterinary surgeon.

Always read the data sheet for any medication carefully before starting as it may recommend a particular needle size. If not, use an appropriate size of syringe and needle (see table below). Generally, shorter needles are used for subcutaneous injections and longer ones for intramuscular.

Needle length and gauge

All needles have a length and a gauge (thickness); the lower the gauge, the thicker the needle i.e. 19g is a thicker needle than 21g.

Most needles fix on the end of the syringe; some come with a Luer Lock, which is a thread in the hub of the needle that allows it to be screwed into other apparatus such as a Slap-shot.

The Slap-shot Flexible Vaccinator has clear flexible tubing with Luer Lock ends that allow you to stand further away from the animal while reducing the risk of losing or breaking the needle. It’s useful for use with pigs and cattle.

Needle re-use and sterilzation

Some needles are re-usable and can be sterilized; others are disposable and are for single use.

Never reuse disposable needles or unsterilized reusable ones. If you are using re-usable needles, sterilize them immediately after use by boiling for 10 minutes and store in sterile conditions.

If your flock / herd has any suspected or confirmed blood-borne disease, a new needle must be used for each animal. Otherwise, several animals may be injected using the same needle. It is advisable to use one sterile needle in the bottle to draw off the medicine, and then change to a second needle to inject.

Never straighten a bent needle and never use bent, dirty or dull needles and never leave a needle in the bottle after use. Dispose of all needles in a proper sharps container so that they don’t get mixed with other rubbish.


Livestock syringes come in various sizes, typically from 2ml to 50ml.

Use a size that is appropriate for the dose you are administering - don't try to judge a 2ml dose in a 20ml syringe for example.

Some syringes are re-usable can can be sterilized; others are disposable and should be discarded after a single session using a single drug.

Syringes have a standard fitting for needles, so almost all needles will fit almost all needles.

If you are vaccinating a large group of animals, self-sterilising vaccination guns and needles are available, such as the Sterimatic Vaccinator. These can save considerable time even for smaller flocks.

Preparing for injecting livestock

Where practicable, the injection site should be clipped free of hair / wool and the skin cleaned with spirit or antiseptic.

When you put the needle on to the syringe, twist it through 90 degrees – this helps to fix both parts together.

Needle sizes and purposes

Length in inches Gauge Application
21g Poultry
21g Poultry; disbudding calves
20g Iron for piglets
20g Vaccines for piglets and lambs
1 20g Antibiotics for piglets and lambs
½ 19g Vaccines for lambs and sheep
½ 18g Vaccines for sheep
¾ 18g Iron for pigs
½ 17g Vaccines for cattle and sheep; Noromectin for pigs
¾ 17g Vaccines for sheep and cattle
1 17g Antibiotics for sheep and cattle
¾ 16g Vaccines and Ivomec for cattle
1 15g Cattle
14g Cattle
1½ - 3 14g Copper injections and flutter valve for cattle

Disposal of clinical waste

Used needles should be put into a sharps container for safety. Used syringes and empty or part empty bottles of medicine, and sharps containers can be take to your vet for proper disposal. Your vet may make a charge for this service.

This is a guide only; the best person to instruct you in effective injection techniques and check that you’re doing it correctly is your vet.

Rosemary Champion

About Rosemary Champion

Rosemary lives on a 12 acre smallholding in Angus, in the east of Scotland, where she keeps Ryeland Sheep, Shetland cattle and assorted poultry. She was destined to be a smallholder from an early age.

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