by: Lee Jones, MS, DVM
University of Georgia
Darts - also known as remote drug delivery devices or RDD devices - are frequently used in wildlife to tranquilize animals for research, or when a wild animal strays into a populated area such as a city or neighborhood. They are also gaining popularity among beef stocker growers who have cattle on extensive grazing. Many times, it is difficult to get a sick animal to the chute for treatment, and roping it on horseback may not be an option. In these situations, the best option may be using a dart gun to treat an animal. But there are some issues that have been raised about the routine use of darts in cattle. There are legitimate situations in which they are useful to reduce animal pain and suffering from disease or other conditions. However, there are some abuses and concerns that have to be addressed. In some cases, darts can do more harm than good; in other cases, it may be the difference between treating an animal safely or not at all. Nevertheless, it is important to minimize the possible negative effects of using darts on animal health and welfare, antibiotic stewardship and muscle damage. Besides those, it is a challenge to use a dart in compliance with BQA standards.
Dart guns come in two basic kinds: those that use gas, such as bottled C02 or air pump, and those that use a cartridge to project the dart. Some darts deliver their dose of drugs either on impact or following impact. Some darts, such as those of Pneu-dart, have a charge in the dart that discharges the medication into the animal after impact. If you think you need to use darts in your operation, do your homework. Dart use should be a necessity, not a convenience choice. RDD equipment is not cheap, and takes practice to learn to use safely and effectively. Some of the companies now have training resources to help teach the proper use of their equipment. The proper use of the equipment is the responsibility of the user. As far as BQA is concerned, the NCBA BQA Advisory Group issued a list of problems associated with using RDD in cattle; this list can be read at http://beef.unl.edu/nebraska-bqa-remote-medication-delivery. I will address a few of these in this article.
One challenge with using darts is getting an accurate dose. Estimating weight is not accurate. At some recent UGA Extension cattle field day events, we challenged attendees to guess body weights on various classes of cattle. As you might suppose, guesses were mostly off, and many were off by more than 25 percent with more under than over. Dosing by guessing will lead to cattle being under-dosed, under-treated, and more than likely treatment failure. The darts come in standard, fixed sizes, such as 5 ml or 10 ml (1 ml = 1 cc) darts; and some come in smaller sizes, such as 1 ml and 1.5 ml darts. Therefore, it isn't possible to adjust the dose according to body weight. Some users will put the medication in the dart, and then fill any leftover space in the dart with water. This changes the medicine, and can result in loss of effectiveness and treatment failure. Besides being illegal, this could also cause injection-site lesions in the tissue, something the industry has tried hard to overcome over the last three decades.
Another challenge to accurate dosing is dart malfunction. Darts that use a built-in charge may not function as intended, and the contents aren't injected into the target animal. In one study, 25 percent of the darts malfunctioned. In my experience, some medication can be lost at impact. I have seen medication sprayed into the air on impact. None of that medicine helped the animal. Careful inspection, and weighing darts before and after use, can help determine whether the animal received the medication or at least the dart expelled it.
Mixing drugs in a dart is absolutely illegal. Not only that, but it can also render both drugs ineffective. The use of flunixine meglemine (also known as Banamine) under the skin leads to nasty tissue damage. Flunixine is approved to be used only intravenously. The flunixine medication is acidic and can react with any other medication, forming a precipitate. To prove this point, take a common antimicrobial and mix with flunixine, and watch the mixture turn cloudy. That drug is now rendered useless and reactive to tissue.
Darts have been found inside the animal during meat fabrication. Can you imagine what would happen if one of our international trading partners found a dart in a box of beef? That could be a million-dollar mistake. Can't happen, you say? A representative from one of the major packers testified that they find about one dart in boxed beef per month. This happens when the RDD user uses too high of a charge for the treatment distance. Animals don't stay still when treating; sometimes they may move closer, and the settings on the RDD equipment aren't adjusted. One way to reduce this is to have a standard practice of dart recovery. This can be a challenge, especially when in areas where animals can run off - such as woods or canyons. Imbedded darts also means that the dart hit a part of the animal's body that is not a BQA-approved injection site. If the dart hits the animal in the neck - which is the approved injection area - with enough force to penetrate the tissue, then serious damage or injury can result. Again, it is the responsibility of the user to use this equipment correctly and safely.
I have performed necropsies on enough calves that have been darted to know that there is significant tissue damage with using darts. Some calves had abscesses at the impact site. Most of our approved livestock drugs are approved only for subcutaneous injection. There is no control over where the darts inject their contents. It could be in the muscle, SQ, or even in the abdomen. RDD equipment companies have tried to address this issue by making short needles with side injection ports. This would hopefully improve the chances of getting the medication SQ and reduce chances of significant tissue damage.
Most darts are single-use. That is good, but there are darts that can be reused. Sterility can become an issue, and lead to injection-site abscesses and medication failure. If you have equipment that can be reused, it is important to boil the darts and clean them, much like you would a reusable vaccination gun. Avoid any disinfectant residues in the darts; and make sure that the needles are clean, straight and free from any burrs - or better yet, use only new needles.
Remote delivery equipment has legitimate uses for cattle health and welfare. It is imperative that we take appropriate measures to make sure that all people using this equipment have training to use it safely and effectively. Also � where possible, it is extremely important to follow BQA standards, understanding that this is a serious challenge and issue when using RDD equipment. Accuracy is also critical. Some animals have been missed, and an unintended animal treated. This not only has significant cost; but it is also important to record accidents just like all other records, and treat only properly identified animals. Records are just as important for pasture treating as for treating in the chute.
RDD equipment isn't for routine herd health use, but to improve livestock health and welfare in situations where it is in the animal's best interest to pasture treat. Responsible use of RDD will ensure the future access to this tool.
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