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Giving It Your Best Shot

Most vaccines and antibiotics are given intramuscularly (IM) or subcutaneously (SubQ). Some medications are given intravenously (IV).


IM injections are given with a needle long enough to go deep into muscle. For an adult cow you need a needle at least 1.5-inches long, and 2-inches is better. Use a 16-gauge needle — large enough diameter to go through a cow’s thick skin without bending or breaking. Don’t use anything larger than 16 or there’s more chance for tissue damage and for the product leaking back out. For a calf, use a smaller needle; 18 gauge and one-to 1.5-inches long works best.

The biggest mistake people make when vaccinating cattle, especially when running a lot of cattle through the chute, is not taking time to do a good job. Hurried work and improper injection may result in some animals not being adequately vaccinated (some of the product leaks out), and increases risk of tissue damage, abscesses, and reactions. To reduce chances of leakage after injection, keep the needle inserted for at least two seconds after the injection, before removing it from the muscle.

Another way to prevent leakage is to pull the skin taut across the injection site with one hand while you inject with the other, then release the skin after you remove the needle. The skin then moves over the hole and closes it. You can also rub the injection site briefly afterward to help distribute the product within the muscle and reduce pressure so it’s less apt to ooze back out.

When using a trigger-type syringe for IM shots, it’s easy to thrust the needle into muscle and pull the trigger. When using a smaller or disposable syringe, detach the needle and press your hand firmly against the skin to desensitize the site so the animal won’t jump when you insert the needle. Then thrust it in quickly and forcefully. A new, sharp needle always goes in easier and causes less pain and damage than a dull one. If the animal jumps, wait until she settles down before attaching the syringe to the inserted needle and giving the injection. If the needle starts to ooze blood, you’ve hit a vein. Take it out and try a different spot. Never inject intramuscular products into a blood vessel.


Originally, SubQ injections were used because a particular product was highly irritating to muscle tissue or designed for slower rate of absorption. Today, due to concerns about carcass quality (avoiding IM shots, where possible) more injectables are being approved for subcutaneous use and no longer must be given IM. When you have a choice, according to label directions, it’s best to inject under the skin rather than into muscle, for less tissue damage. IM shots are more likely to develop an abscess if a needle is dirty. An infection introduced by a SubQ shot is merely beneath the skin and an abscess more readily breaks open to drain.

For a SubQ injection, lift a fold of skin on neck or shoulder where skin is loosest, and slip the needle in between skin and muscle. If using a trigger-type syringe, aim it alongside the animal so the needle goes under the skin and not into muscle. For a small calf, it may be easiest to give a SubQ injection under the loose skin of the shoulder, and if there’s a local reaction it won’t make his neck sore.

Giving injections SubQ rather than IM allows you to use a shorter needle (-inch if using a trigger type syringe, or up to 1-inch if using both hands to tent the skin and slip the needle underneath) so it’s less likely to bend or break. In the confined space of some chutes, insert the needle at an angle so you can use a one-handed technique with a syringe gun, rather than both hands to tent the skin. There’s less risk of getting your hands injured (jammed between the animal and the chute) or accidentally hitting yourself with the needle, if you can do it one handed.


Some medications are more effective (acting faster and more readily absorbed) if given IV. Some are irritating to muscle tissue and must be given IV. These injections must be done properly. Chances for problems are greater, as is the speed with which a serious problem may develop, so you must know which products can be given IV (follow label directions) and know what you are doing. Large volumes of fluid or medications given too swiftly can put too much load on the heart, and some drugs speed up the heart. Heart rate should be monitored when giving fluids or certain IV medications, and rate of administration adjusted accordingly.

Any large vein will work for an IV injection, including the large veins under the tail, the big milk vein ahead of the udder on a lactating cow, or the jugular vein on either side of the neck (located in the groove above windpipe and esophagus). A large needle (at least 16-gauge and 2-inches long or longer) works best for adult animals.

For IV injections, needles and any other equipment must be sterile. The animal must be well restrained so it can’t move around during the procedure. If using the jugular vein, find it and press down on it with your fingers or fist to build up pressure (between your hand and the animal’s head) so the vein stands up and is easier to inject. Still pressing on the vein, insert the needle into it at a point between your hand and the animal’s head, then move the needle a little forward (inside the vein) parallel with the neck. If blood flows freely from the needle, this shows it’s in the vein and you can then attach your syringe (or tubing, if giving fluid).

The most common problem is pushing the needle too far, clear through the vein and out the other side. Sometimes the animal moves and the needle slips out of the vein. Don’t just assume it’s in the vein just because you see blood. Blood will flow rapidly and steadily from the needle if it’s actually in the vein. Make sure the needle stays in the vein when you give the injection or administer fluid. Injecting some products into tissues around the vein can cause severe irritation and stress (and sometimes death, depending on the drug). If the needle slips out of the vein while giving fluid, the tissues around the vein start to swell. If the needle slips out of the vein, take it out and start over. If giving fluid (the needle must be in the vein awhile), it’s best to use an IV catheter, which is longer than a needle and more flexible, and stays in the vein better.

HeatherSmithThomasrancheswithher husbandLynnnearSalmon,Idaho.Contact herat208-756-2841

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