by: Carla L. Huston, DVM, PhD
ACVPM Beef Extension and Outreach Coordinator, College of Veterinary Medicine, Mississippi State University

Remote drug delivery (RDD) systems, or dart guns, are being used more and more frequently throughout the beef industry for the delivery of antibiotics. A recent trip to my local livestock supply store showed just as much shelf space dedicated to dart guns as they have for traditional needles and syringes. If you are using or considering using this type of medication delivery system, you should be aware that there is some disagreement within the industry on its use. Many of the concerns, based on the lack of safety and efficacy studies and the inability to meet Beef Quality Assurance (BQA) injectable product administration recommendations, are discussed this month.

Physical examination of cattle is not possible using an RDD system, which could result in an inaccurate disease diagnosis. It may be difficult to identify animals at "darting distances" and prevent them from entering the food supply before their drug withdrawal period has expired. Furthermore, it is difficult to accurately estimate animal weights for proper drug dosing.

Some uses of antibiotics through dart guns may be out of compliance with FDA regulations, resulting in illegal drug use. Specific medications and drug compounds are illegal to administer through darts in cattle, while others may require veterinary oversight under the FDA's Animal Medicinal Drug Use Clarification Act Extralabel Use of a subcutaneous medication could Drugs provisions (Title 21, Code of Federal Regulations, part 530).

You only get one shot with a dart gun, and proper dosing is a big concern. There are few medications that can be delivered in sufficient volume through any RDD system. Most commercial dart gun systems have a maximum delivery volume of 10cc, which limits the choices of antibiotics. Furthermore, darts failed to deliver the full drug dosage in studies performed in both Kansas and Nebraska. Underdosing an animal can result in treatment failure, along with wasted time and money.

The use of darts has been shown to cause excessive swelling, inflammation, and tissue damage, possibly resulting in trim loss of edible tissues at harvest. This could also result in illegal tissue residues that extend beyond the labeled meat withdrawal times. The prescribing veterinarian is responsible for recommending a proper withdrawal time for all products used in this extra-label fashion. A recent study in Texas also showed a decrease in tenderness in the muscle of animals treated through a RDD.

BQA standards require that all medications be administered in front of the shoulder with-in the injection triangle zone. Failure to hit this targeted area can result in excessive tissue damage or other physical injury to the animal. Needles could penetrate underlying ligaments and joints, or other areas such as the head and vertebrae. Multiple cases of lameness have been reported in cattle who were darted in the shoulder or leg regions.

The intramuscular administration of a subcutaneous medication could occur when using a dart gun for drug delivery, or vice versa. This may cause improper drug distribution, decrease drug efficacy, extended meat withdrawal times, and possibly off-label use of the drug.

Proper drug delivery requires that the proper gun charges are used relative to the distance that the animal will be targeted. Improper charge and/or distance calculations can result in extreme tissue damage or in darts becoming embedded in the muscle. There have been reports of darts being found in carcasses at the slaughter plant and during carcass fabrication, resulting in an adulterated product.

Darts left in a pasture can pose a physical hazard to both animals as well as people. Darts should be retrieved each time an animal is treated to reduce environmental contamination. This can be challenging as darts may take over an hour to fall off of an animal according to recent Iowa State research.

Animals have been known to become "gun-shy" following treatment with a dart gun, resulting in undesirable animal behavior. Aversion to vehicles or people can also result when animals are repeatedly shot with darts. Cattle that are routinely stressed are more susceptible to injury, can become immune compromised, and can become "dark cutters" at harvest.

Of course, the use of the RDD technology can offer some advantages to the cattle producer by allowing cattle to be treated quickly in remote areas that lack handling facilities. It is a fact that cattle get sick on pasture every day, and if handling facilities are not close by we are left with few options. No one wants to see sick animals go untreated, and in some cases, moving a sick animal long distances to a handling facility could be detrimental. From an animal welfare standpoint, treatment through a RDD may be indicated to control animal illnesses or prevent death. However, remote drug delivery systems should not be used out of convenience or to routinely treat cattle.

Education on the proper use of RDD systems is critical if you are using or considering using this technology to treat cattle. If you decide to use an RDD system, take appropriate steps to reduce or eliminate the concerns described above. Work with your veterinarian to develop protocols for treating specific conditions through RDD, and make sure that all treatments are recorded to prevent any potential residues. Use tags or brands that can easily identify cattle from a distance. Practice hitting a small targeted area using your dart gun before actually treating animals, and understand variations in load and distance. As always, contact your local veterinarian if you have questions on animal health and welfare, and the use of RDD systems on your operation.

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