With larger farming operations and labour at a premium the switch to automatic guns for vaccination and other pharmaceutical administration is very common. Although there are tremendous advantages to this, primarily in speed of administration and accuracy, there are several pitfalls producers should watch out for.
In their day, the older-style automatic roux syringes with the glass barrels and expandable plungers made life easier. However they were prone to breakage of the barrels and needed constant adjustment to prevent air from leaking into the barrel. The way the plunger was designed you sometimes were never sure whether four or five cc was administered. At the higher dosages a difference of one cc was not great but with most newer vaccines where the regular dose is two cc that difference of one cc represents 50 per cent of the dosage (a huge difference).
The newer syringes such as the Phillips are very accurate at these lower dosages and have a safety mechanism whereby air cannot enter the syringe when vaccinating. They are a little harder to depress as the barrel is large but if well maintained slide easily. You should have some spare parts on hand and properly maintain them. After usage a good cleaning with warm water followed by slight lubrication with cooking oil on the O-ring will keep it supple.
Some products like penicillin and the new product Excede cause rubber O-rings to expand and will cause a great deal of sticking. You will find the same if you use the plastic disposable syringes with these products. Very quickly the rubber on the plunger becomes extremely sticky. The way to avoid this problem is purchase a syringe automatic or otherwise with a silicone O-ring replacing the rubber.
I always remind producers to monitor the usage of a product as a check on whether too much or too little is being dispensed. A 50-dose vial of vaccine should pretty much be empty after 50 head. If administering two vaccines, compare their usage to each other. Some vaccines will have one or two doses extra but that is all. Too much or too little vaccine left may alert you immediately to a syringe incorrectly set or one that is not dosing correctly. I have seen where guns have been bumped and the dosage changed.
Keep the syringes labelled so products are not inadvertently mixed. If for instance a modified live vaccine is mistakenly sucked up into the syringe which just had blackleg in it the formalin carrier will completely inactivate the live vaccine. This potential wreck must be instilled in your processing crew. Another trick to avoid mixing products is to refill before the syringe is completely empty. Most products have a different color which should clue a person in. I also have the syringes far enough apart and inject in a certain order and location to keep everything consistent. Good processing crews are very methodical this way and spend time after cleaning and maintaining their syringes.
The auto-fill syringes where the bottle is attached to the syringe do eliminate time filling and are quite accurate as well. Often several holes need to be poked in the bottle to allow the plastic drain needle to penetrate the rubber stopcock. Again one must be very careful to monitor how much product is being used. In older models a piece of rubber could block the exit and the product was not being dispensed or at a greatly reduced rate. The product would simply flow in and out of the bottle and was not being injected into the animal. Always, always monitor usage.
Producers pay good money for vaccines so it is important to make sure the product is handled well, mixed well and properly administered at the right dosage. We definitely can t have freezing of the products and overheating needs to be avoided as well.
Most automatic guns can be used with the one-handed technique and it is often easier to feel when needles are getting dull and need to be changed.
This is no fault of the syringes but always double-check dosage and preferred route of administration. Different trade names may use different dosages. Combination products often have a higher dosage. It is too late if the entire herd is processed and you find out the dosage of a vaccine was four cc and you gave two cc. Essentially the entire herd should be re-run and the other two cc given. If you are giving too high a dosage this mistake shows itself quicker when you run out of vaccine and still have lots of cattle to process. All these are costly mistakes and are avoidable if a few minutes are taken to go over things and double-check your syringes. Try and have the same personnel do the same jobs throughout the day. If everyone is jumping around animals may be missed or double vaccinated.
If all the above pitfalls are avoided you should have an uneventful time processing. You will get the maximum benefit from the products you inject.