Pinkeye, foot rot, bovine respiratory disease: These are all common cattle infections producers want treated, and treated quickly. With time and access to facilities being a common constraint on many operations, it’s reasonable to opt for the most convenient drug delivery device – a dart gun.
In a University of Nebraska – Lincoln webinar, Dr. Brian Vander Ley, veterinary epidemiologist at the Great Plains Veterinary Education Center – Clay Center, Nebraska, weighs the convenience and efficiency of dart gun use against three key limitations:
1. Distance diagnostics
Diagnosing from a distance can limit judgement of the animal’s needs. Determining condition, and therefore the correct treatment, can be challenging if the animal is not physically examined.
“In some instances, like pinkeye, it can be much simpler to make a diagnosis,” Vander Ley says, “but when you’re talking about diseases like foot rot or respiratory disease, it’s far more difficult to make that diagnosis without getting hands-on.”
Poor accuracy not only impacts humane and successful treatment of the animal – it hurts the pocketbook as well. Failure to administer treatment in the proper location could potentially alter the drug’s effectiveness and incur additional cost to replace the wasted product.
Dr. Johann Coetzee, professor and head of the Department of Anatomy and Physiology at Kansas State University, conducted a study in 2018 examining dart accuracy and found that five of 15 darts administered at a 30-foot distance did not land in the triangle injection site recommended by the Beef Quality Assurance (BQA).
Attempting to treat an animal from a distance presents the risk of accidentally injecting at an ineffective or harmful location point. A dart injected too high above the BQA triangle could hit the large ligament supporting the calf’s head. The limited blood supply in this ligament could significantly alter the calf’s absorption of the drug and its success in treating the problem. Additionally, if a dart is administered too far below the BQA triangle, hitting the jugular vein with a drug not designed for intravenous injection is a possible consequence.
Dr. Daniel Rivera, a ruminant nutritionist at Mississippi State University, conducted a study in 2019 that found dart accuracy can be significantly improved by simply reducing the administration distance from 30 feet to 15-25 feet.
Vander Ley notes that even with this alteration, it should be noted that in both studies the animals were restrained by a chute or halter with the injection triangle clearly accessible.
According to Coetzee’s study, four out of 15 darts failed to inject the drug on impact, and in Rivera’s study, three out of 15 darts failed to inject.
“People use darts because they’re convenient and they reduce stress,” Vander Ley says, “but that needs to be balanced against the fact that up to 20 percent to 30 percent of the darts you send toward an animal are not actually going to deliver the drug.”
Darts that fail to discharge decrease the animal’s chance at recovery by wasting valuable time needed to treat the disease.
Vander Ley highlights several liabilities associated with dart gun use but focuses primarily on a concern not unique to drug delivery devices – adulteration of meat. One cause of meat adulteration is administering the incorrect dosage as a result of guessing an animal’s weight.
“The dose we come up with is only as good as our ability to correctly estimate weight,” Vander Ley says. “We can end up with significant problems with residues if we overdose drugs based on estimating the weight too high.” Instead of depending on a visual estimate of weight, Vander Ley recommends using a scale to avoid overdosing or underdosing the animal.
“It’s important to point out that BQA does not make any room for dart gun use,” Vander Ley says. “If you’re going to use dart guns, there are some things you really need to think about.”
Vander Ley provides seven important things to consider before opting to use a dart gun:
- Confidence in diagnosis
- Obtaining correct weight of the animal
- Operator accuracy and animal compliance
- Possibility of dart malfunction
- Slaughter withdrawal time
- Dart recovery after administration
- Backup plan if an animal still requires treatment.
SOURCE: Progressive Cattle Editorial Intern Kate James Published on 29 June 2021
PHOTO: Using drug delivery devices like dart guns comes with many limitations to consider. Photo by David Cooper.