The use of pneumatic darts for remote drug delivery (RDD) has become increasingly popular as a tool for treating sick cattle in the field, particularly in remote or inaccessible pastures where it is difficult or risky to capture, restrain or transport animals for conventional treatment. The practice has raised concerns, however, particularly in terms of beef quality assurance, due to potential for improper injection sites, inappropriate doses of antibiotics, injury to animals, broken needles remaining in cattle and a long list of other possible consequences.

Watch for our September 2016 issue for comprehensive coverage of the RDD issue. Meanwhile, we are interested to hear of your experiences with the mechanical function of RDD darts in the field.

In response to the rapid growth in the use of pneumatic darts for delivering antibiotics to cattle, researchers at several universities currently are conducting tests to evaluate the systems for drug delivery, disposition and efficacy, impacts on meat quality and other factors.

At Iowa State University, a team of researchers led by Hans Coetzee, BVSc, Cert CHP, PhD, DACVCP, DACAW, recently complete an experiment evaluating the use of RDD for treatment with tulathromycin, and resulting physiological effects on the animal.

Tulathromycin  is a macrolide antibiotic indicated for the treatment of bacterial infections associated with bovine respiratory disease complex, infectious bovine keratoconjunctivitis and interdigital necrobacillosis. Low injection volume and long duration of activity after a single injection has resulted in tulathromycin becoming a popular choice for RDD in cattle, but the researchers note a lack of data describing the impact of RDD on injection site tolerance and tissue residue depletion.

In this test, the researchers used 15 Holstein calves weighing between 750 and 900 pounds, injecting each with 10 mL of tulathromycin using a pneumatic dart equipped with a ¾-inch, 14-gauge needle.

The researchers restrained each animal in a mobile chute and delivered the dart from a consistent distance of 9.1 meter, or just under 30 feet. Following the injections, they collected blood samples from each calf to measure levels of tulathromycin, cortisol, creatine kinase (CK) and aspartate aminotransferase (AST). They also used thermography, visual measurements and mechanical nociceptive threshold (MNT) assessment to measure inflammation and pain at injection sites and euthanized three animals at 24 hours post-treatment to inspect injection sites at necropsy.