Welcome back to the American Cattlemen Podcast. Just ahead, we have Dustin Hector, he's the Director of Business Development for American Cattlemen Media, and he sits down with Dr. Will McCauley, Director of Industry and Government Relations Manager for Medgene. In this episode, Dr. McCauley and Dustin will dive into everything ectoparasites including, some examples of ectoparasites, how they harm cattle, and some preventative measures producers can take to minimize their damage. 

A three-time graduate of Texas A&M University, Dr. McCauley earned his DVM and MBA in 2012 and 2010, respectively. His career spans clinical practice, regulatory leadership, and corporate relations, including his previous role as Director of Corporate Relations at the Texas A&M Foundation. He is heavily involved in professional advocacy, serving on the Texas Veterinary Medical Association Board of Directors and maintaining active roles with the AVMA and the Brazos Valley VMA.

Dr. McCauley explains that ectoparasites cause harm in two primary ways: as vectors transmitting infectious diseases and as a direct drag on performance. He highlights ticks as a major economic concern, noting that they cause billions of dollars in losses globally, largely due to the diseases they spread rather than their feeding alone. A timely example is Theileria, a blood-borne protozoan transmitted by the invasive Asian longhorned tick, which is spreading across parts of the United States and producing clinical signs similar to anaplasmosis, including anemia, lethargy, respiratory difficulty, and jaundice.

Ectoparasites also reduce productivity even when they are not transmitting disease. Horn flies illustrate this second category of harm. These flies are widespread and feed aggressively, biting cattle dozens of times per day. High fly pressure leads to behavioral changes—such as bunching in corners, seeking shade or brush, or standing in ponds—that reduce grazing time, slow weight gain, and decrease milk production, resulting in substantial economic losses for producers.

Dr. McCauley reviews traditional control methods such as medicated ear tags, pour-ons, and fly bags, noting that their effectiveness has declined over time due to parasite resistance and longer parasite seasons associated with milder winters. He then describes Medgene’s prescription platform vaccines, which take a generational approach by reducing parasite populations over time, largely by decreasing reproductive output rather than causing an immediate knockdown. Because these are prescription products, he emphasizes the importance of a strong veterinarian–client–patient relationship and a multi-tool strategy that combines vaccines with other management practices to sustainably manage ectoparasite pressure and protect herd productivity.

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