Dr. Steve Hendrick of the Coaldale Veterinary Clinic, Coaldale, Alta., urges his clients to clean their syringes every time they are used. “For the syringes and pistol-grip syringe guns we use for administering killed virus vaccines, bacterins, toxoids or the products that give protection against bacterial pneumonia, we can clean with a mild dish detergent. We can take the syringes apart and make sure we get everything clean. There are bottle brushes that will fit into a syringe, which a person can use for cleaning, if necessary. The important thing is to make sure they get rinsed well, especially after using a detergent or disinfectant,” he says.
“With guns or syringes that you use for modified live virus (MLV) vaccines, we recommend you not use any soap or disinfectant. Any residue would inactivate the MLV vaccine.
“Generally I follow that recommendation, but occasionally a person encounters a situation where the syringes got really dirty and you almost have to use soap along with the hot water, to get them completely clean. I don’t think it’s bad to use a detergent, if you make absolutely sure there is no residue. You really need to rinse and rinse multiple times afterward. If there’s any residue, you will be wasting your time and money on that vaccine because it won’t be effective.
“Some people think that if the disinfectant kills it, it would be just like a killed vaccine, but that’s not true. They are not the same. The MLV vaccine is not adjuvanted, and the amount of organism in the product is of much lower level because it is expected to be still alive and able to grow within the animal and stimulate an immune response. If you kill it, the MLV vaccine will not work effectively,” says Hendrick.
The method suggested by veterinarians is to use boiling water, according to Heidi Carroll, livestock stewardship extension associate, South Dakota State University.
“A person might first rinse the syringe with hot tap water, to flush out most of the vaccine residue, and also to heat up the syringe so that the boiling water won’t break it, especially if it’s a glass-barrel syringe.
“Then you can pull the boiling water up into the syringe, rinse it out, pull in some more, and keep rinsing it several times. Most veterinarians recommend doing this five to 10 times, making sure that all of the interior comes into contact with hot water. If the guns can be taken apart, disassemble them.
“Then the goal is to let them air dry before you put them away. Don’t store syringes wet; you want them to be dry. You might set them on a clean towel to allow them to finish drying,” she says.
How you store syringes between uses is also important. “Once you’ve gone through all the cleaning processes, you don’t want them to get dusty. Choose a storage place that will keep it clean. Put the syringe into a large Ziploc bag, once it is completely dry, and then put the bag into the cupboard or tool box where you keep your supplies,” says Carroll.
“Another trick is to use one particular gun or syringe for a certain vaccine, and no other. You can label them or colour-code them with tape, so you’ll be less apt to get them mixed up when refilling syringes at the chute. It’s also important to keep all your vaccine syringes separate from any you might use with antibiotics.” You never want an antibiotic in a syringe that you might later use for a vaccine.
“When you take syringes and guns apart to clean, check the rubber O rings,” says Hendrick. “They tend to break down, over time. This is an area where you could get some unwanted growth of bacteria, or some residue (inside the tiny cracks). Make sure you change those periodically, especially if they are starting to wear out,” he says.
If the plunger rubbers start to stick, it’s wise to lubricate them after you clean the syringe, so they won’t be stuck and tight the next time you use it. People often use mineral oil for this purpose, but glycerin or vegetable oil may actually work better. Mineral oil tends to break down the rubber over time. The best thing, according to Hendrick, is to just replace these O rings on a regular basis. Then you don’t have to worry about a lubricant possibly interfering with a vaccine.
“If you are giving a large volume, follow label directions and break it up into multiple smaller injections, at different sites,” he says. It will be absorbed better if injected into multiple locations and not all in one area. This is also very important in terms of meat withdrawals. Antibiotics mistakenly given via the wrong route can have serious consequences.
Also be sure the needle length is appropriate. You only need a short needle, for example, for subcutaneous injections. “With some products, like some vaccines or some hormones, the dose may be as small as one or two ml and if these are going IM you need to make sure you have a long enough needle, at least 1.5 inches. You don’t want any of it to leak back out,” warns Hendrick.
“For subcutaneous injections in a calf with a thin hide a half-inch needle is plenty. On a bull, for a subcutaneous injection, it might take a three-quarter-inch needle. Also, it might depend on whether you are using a pistol-grip repeater gun and just aiming it in at a slight angle (to go under the hide), or tenting the skin with your other hand, to slide the needle in under the skin. In that situation you might do best with a longer needle.” It depends on the situation and how you are administering the injection.
“For most treatments out in the pasture, or even in feedlots, people are generally not using a pistol-grip gun. With some of these injections you might tend to use a bit longer needle. Each person might also have preference for what works best for them which is fine, provided the drugs are administered in the proper location.
“It all depends on the angle, and whether you go right up to the hub or not. If you are giving an IM injection and don’t put the needle in all the way, or the animal jumps, it might not go in deep enough. I think 1.5 inch might be the safest length to use from that standpoint — to make sure you are actually getting into the muscle. In a calm, quiet animal, one inch might be sufficient, but that extra half inch is a good idea in many cases,” he says. If it doesn’t go in all the way or some leaks back, it may end up mostly under the skin rather than in the muscle, which may affect the efficacy of the product.
Another question often raised is how often you should change needles. “For treatment of sick animals, you should ideally use a new needle for each animal. On the farm, a person may be only treating one animal at that point in time anyway, and it’s just best to use a new needle. When it comes to vaccinating a group of animals, however, people generally inject multiple animals before changing needles. We advise our producers to try and change needles every 10 animals,” says Hendrick.
If you keep using the same needle, it becomes dull, and won’t go through the hide as readily. “You’ll feel it, and can tell a difference, and by that time it’s dull enough to cause more tissue damage and more pain to the animal. I’ve been in situations where we’ve used needles for more than 10 animals — to do the job — but we wonder how much trauma we are creating,” he says.
“There’s also more chance for contamination, and sharing that contamination with other animals. It’s better to just change needles, and have a systematic process such as changing after 10 animals, or changing each time you refill the syringe from a 10-dose bottle. You can therefore use a new needle for every draw-up. Definitely use a sterile needle for every insertion into the vaccine bottle,” he says.
Always change needles if the one you are using gets bent. Some people try to straighten it and keep going, but this is dangerous. “Once a needle has been bent, you’ve created a weakness and it may break. You don’t want it breaking off in the animal.” If it’s very bent it will also create more tissue damage as it goes in, and the angle may be wrong for injecting that vaccine where you want it.
“If you are getting too many bent needles, there’s something wrong. The animals may not be adequately restrained and are jumping around while you are trying to give that injection. They may not be squeezed enough, or maybe not squeezed at all. Not everyone has a perfect chute, and sometimes people have to be a little creative and careful to not get into a problem while vaccinating.” If the animal jumps at the wrong time, you might get your hand or arm injured, or end up with a broken syringe.
“The plastic syringes in use today may not break as readily as the glass ones. We still see some glass syringes in use, however,” he says.
If you are using a transfer needle when rehydrating MLV vaccines, make sure it is clean and sterile before you start. Sometimes people forget about those when cleaning syringes afterward. “They may just leave it in the box and use it again next year, but it needs to be rinsed out, too,” says Hendrick.