A recent study from Texas A&M University indicates that many bison producers are deworming their herds on a set schedule rather than based on diagnostic recommendations. Researchers warn that this practice may promote the development of drug-resistant parasites. Gastrointestinal parasites pose a significant economic challenge for bison producers in North America, and overuse of deworming medications can quickly diminish their effectiveness.
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Dr. Kaylee Kipp, a recent graduate of the Texas A&M College of Veterinary Medicine and Biomedical Sciences, emphasized that gastrointestinal nematodes create serious health issues for bison, often presenting a heavier burden than seen in beef cattle. The unmonitored presence of these worms can result in significant health problems, including diarrhea, poor weight gain, and, in severe cases, increased mortality rates among adult bison.
Understanding the management practices of bison farms is crucial, especially as much of the existing research pertains to larger herds in the northern U.S. and Canada. Dr. Guilherme Verocai, an associate professor in veterinary pathobiology at Texas A&M, noted the need to distinguish between operations managing herds of varying sizes.
The research team surveyed bison producers regarding herd demographics and parasite control methods. Findings revealed that nearly 90% dewormed their bison at least once a year, with about one-third doing so more than twice annually. However, diagnostic tools to confirm treatment needs were seldom utilized, and producers often applied methods from the cattle industry.
Bison present unique challenges; handling them is more difficult than with cattle, which may lead some producers to resort to alternatives like medicated feed. Additionally, there is a limited selection of FDA-approved anthelmintics specifically for bison, leading many to rely on strategies designed for other ruminants.
The concern about anthelmintic resistance parallels issues seen with antibiotic resistance. Repeated use of dewormers can lead to a higher proportion of resistant parasites in the population. Verocai expressed concern that without intervention, the majority of parasites could become resistant, particularly as new drug options are scarce.
One recommended strategy is the use of diagnostic testing, such as fecal assays, to identify present parasites and determine whether treatment is necessary. This targeted approach could potentially reduce overall drug use and lessen the selection pressure contributing to resistance. Verocai noted that while collecting and sending samples for testing may seem labor-intensive, it could ultimately save money and extend the effectiveness of existing drugs.
Another proposed strategy is to incorporate 'refugia,' which involves intentionally leaving some animals untreated to maintain a population of drug-susceptible parasites. However, fewer than 10% of producers reported using this approach. Kipp highlighted that discussions about refugia are critical for long-term parasite management.
Overall, the study underscores the need for producers to adopt more focused and strategic parasite management practices rather than implementing blanket treatment schedules. Kipp pointed out that managing bison also involves managing the parasites they carry, emphasizing the diversity in herd management, environment, and drug access. The research aims to establish foundational practices that promote effective parasite control tailored to the needs of bison herds.
This study was supported by the Texas A&M College of Veterinary Medicine and Biomedical Sciences, featuring contributions from Dr. Kaylee Kipp and Dr. Guilherme Verocai.