Needles & injections

Depiction of several different needle gauges. You will likely never use a 30 gauge needle, however it is shown for comparison.

Welcome to part one of our series on needles and injections! In this post, we will discuss the difference between subcutaneous (sub-Q or SQ), and intramuscular (IM) injections and the needle sizes best suited for each. 

A subcutaneous injection delivers medication under the animal’s skin but not deep enough to go into the muscle. A common medication that most producers will utilize in their sheep operation is CD and T. Most commonly, SQ injections are given in the sheep’s neck or over the ribs by pinching the skin to create a “tent”. Creating this “tent” helps ensure that the medication does not go into the muscle. 

Intramuscular, or IM, injections are medications administered directly into the sheep’s muscle. Commonly, IM medications are administered into the muscle of the neck.  

                      Let's talk needles!
Needles are categorized by gauge, or size, that the hole of the needle is. Needle lengths can also be different despite being the same-sized gauge. Contrary to what one might think, the larger the number of gauge, the smaller the needle hole is. On the flip side, the smaller the gauge’s number is, the larger the needle hole will be. For example, a 20 gauge needle is smaller in size than an 18 gauge needle. A 16 gauge needle is larger in size than a 22 gauge needle. 

How do I know which needle to use?
Typically, 18 or 20 gauge needles are utilized for sheep older than one week. 22  gauge can be used for lambs less than one week old as the needle may be too flimsy for older lambs.  Generally, an SQ needle is 0.5 to 1 inch long. IM needles should be 1 to 1.5 inches long because the needle needs to be long enough to penetrate the muscle. 
SQ: A 20 gauge, 0.5 inch long needle would be reasonable to use for SQ injections.
​IM: An 18 or 20 gauge, 1.5 inch long needle would be reasonable to use for IM injections. 

• One item to consider is the thickness of the medication that you are administering. A thin liquid will easily be able to be injected in a 20 gauge needle. However, a thicker liquid might be more easily injected using an 18 gauge needle. 

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                                         Considerations

• If you will be administering more than one injection at a time, choose another site at least one hand's width away from the previous injection side. 
• You should not administer more than 5 mL of medication on one site. For example, if you give 5 mL of a medication sub-q on the right neck, you should switch to the left neck to administer other medications at that time.
• A needle should only be used for approximately 8-10 sheep at a time before needing to be changed. Needles should also be changed if they are bent, broken, or dull.
• Syringes and needles both need to be luer lock in order to be compatible. 

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                       Some of our favorites!
These are links to some of our favorite products to use for injections!
5 mL Luer Lock syringes: https://amzn.to/4fPgsO2
18 gauge needles (1 inch): https://amzn.to/4fvrsQT
20 gauge needles (1 inch)18 : https://amzn.to/3YQCid8

​Disclaimer: I am NOT a licensed veterinarian. The information on this site is for informational purposes only and should not be used as a substitute for professional veterinarian advice. Please contact your veterinarian. Any purchases through the Amazon links generate commission for this website. ​

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