Is Your Herd at Risk? Unveiling the Hidden Threats of Johne's Disease and BVD
"A deep dive into the prevalence of Johne's Disease and Bovine Viral Diarrhea (BVD) in dairy herds, offering crucial insights for early detection and proactive management."
Johne's disease (JD), caused by Mycobacterium avium subsp. paratuberculosis (MAP), and Bovine Viral Diarrhea (BVD) pose significant threats to the health and productivity of dairy herds. JD leads to chronic digestive issues, impacting weight, milk production, and overall well-being of cattle, increasing culling risks. BVD, on the other hand, causes a range of reproductive and respiratory problems, resulting in substantial financial losses for dairy farmers.
Despite increased awareness, many dairy herds remain affected by JD and BVD, leading to reduced profitability and compromised animal welfare. Determining the prevalence of these diseases and understanding the associated risk factors are crucial for implementing effective control measures. Understanding the prevalence of these diseases and adopting appropriate management practices are vital for mitigating risks and ensuring the long-term health and sustainability of dairy operations.
This article explores the findings of a study conducted in the Intermountain West of the U.S.A., which assessed the herd-level prevalence of JD and BVD. It looks at farm management practices and characteristics linked to test-positive herds, offering valuable insights for dairy farmers looking to protect their investments. Learn practical strategies for early detection, biosecurity, and vaccination to minimize the impact of these costly diseases.
A Persistent Herd Health Risk
Johne’s disease and BVD remain important herd-health concerns that can develop quietly before their effects become obvious. Their hidden nature can make early recognition and control difficult, particularly when signs are not yet apparent. The practical impact may include animal-health challenges, management disruption, and economic pressure, although the scale varies among herds.
Control Measures and Their Limits
Johne’s disease control programs commonly combine testing, management changes, and efforts to reduce transmission, but their effectiveness and economic impact vary among programs. A 2023 systematic review found that the factors driving farmers’ decisions to implement control practices remain insufficiently understood. Vaccination may reduce clinical disease, according to the University of Edinburgh guidance, but it does not prevent infection transmission and can interfere with milk and blood tests used in eradication schemes.
An Established but Evolving Challenge
Johne’s disease has been recognized as a longstanding livestock-health problem, and control efforts have developed over time as diagnostic and management knowledge expanded. The historical record suggests that progress has been gradual rather than uniform across herds. Earlier approaches continue to inform current practice, while remaining limitations have encouraged ongoing research into improved prevention and detection.
What Does the Research Say About Disease Prevalence?
The study revealed that 38% of dairy farms tested positive for Johne's Disease (JD), while 9% tested positive for Bovine Viral Diarrhea (BVD). A small percentage (3%) of farms were affected by both diseases. These numbers highlight the widespread presence of these diseases in dairy herds, emphasizing the need for proactive monitoring and control strategies. Note that the sensitivity of bulk tank milk testing varied (54% for JD, 35% for BVD), meaning that a negative test doesn't completely rule out the presence of the disease within the herd.
- Clinical Signs: A large majority (81%) of farms with JD had observed adult cows becoming thin despite maintaining a good appetite, while 52% had seen adult cows contract diarrhea and die. Both BVD-positive farms reported instances of abortions.
- Housing: Free stalls were the primary housing for milking cows on 91% of farms, while dry lots housed dry cows on 55%. This is important because housing type and management can impact disease transmission.
- Replacements: A large portion of farmers (41%) bought new animals in the last year, mostly pregnant heifers (27%) and bulls (18%). However, of these farms, many (64%) did no testing or segregation.
Research Focuses on Earlier Control
A 2025 invited review examines advances in Johne’s disease diagnostics and management, with particular attention to including young stock in effective testing strategies. A 2026 Frontiers study addresses age-adjusted ELISA cutoffs for Johne’s disease, reflecting continued effort to improve interpretation of diagnostic results. AHDB also reports that recent studies are investigating how the disease spreads and how herds can be better protected.
Implementation Remains Difficult
Johne’s disease is not only a dairy concern; a 2024 K-State Beef Tips article argues that veterinarians, animal scientists, and cow-calf producers should discuss it before declining consumer confidence or pressure for additional beef-industry regulation becomes a larger issue. A systematic review identifies interacting drivers and barriers that influence whether dairy farmers implement control practices. Herd-specific protocols can help tailor responses, but DairyMD reports that vaccine protection has so far been largely unsuccessful, even as researchers continue pursuing vaccine solutions.
The Hidden Herd Burden
APHIS describes a clinical Stage IV case as the “tip of the iceberg,” estimating that 15 to 25 other dairy cattle may be infected for every obvious case. In Great Britain, herds in the worst quartile by annual test value accounted for 42% of positive Johne’s disease tests and had 7.6 times more positive tests than herds in the best quartile. These findings underscore how visible clinical disease and underlying herd-level infection can differ substantially, while UW–Madison states that control programs can control and even eliminate infection from infected herds.
Protecting Your Herd: Actionable Steps for Dairy Farmers
The study's findings paint a concerning picture of the prevalence and management of JD and BVD in dairy herds. While the study was limited to a specific geographic region, the issues and potential solutions are applicable to dairy farms across the country. Now that you're aware of the risks, what can you do to protect your herd and your livelihood?
Control Requires Persistence
The available evidence suggests that Johne’s disease control is best understood as an ongoing herd-management process rather than a single intervention. Outcomes depend on how consistently detection, prevention, and management measures are applied. Because disease can remain hidden, informed veterinary guidance and sustained monitoring may be important to achieving meaningful progress.
Improving Detection and Prevention
Future progress is likely to depend on better detection, clearer interpretation of test results, and management strategies that address infection before clinical disease appears. Research may also continue exploring improved vaccines and more practical herd-level control programs. Advances will need to be evaluated not only for biological effectiveness but also for feasibility on working farms.
A Challenge Beyond Individual Animals
Johne’s disease illustrates how herd health, farm economics, veterinary decision-making, and public confidence can intersect. Control is influenced not only by available science but also by whether producers can adopt recommended practices consistently. Differences among herds and production systems mean that broad recommendations may require local adaptation.
Economic and Collaborative Consequences
Economic studies have used approaches such as Markov chain Monte Carlo simulation to estimate annual losses per cow in MAP-infected herds and total regional losses using region-specific economic variables. The U.S. National Johne’s Disease Demonstration Herd Project evaluated farm-level economic costs and benefits associated with paratuberculosis control in dairy herds. A Leicestershire case study reports success associated with a thorough control plan and close collaboration between the veterinarian and farmer.
Based on the research, here are some actionable steps dairy farmers can take: Implement robust biosecurity protocols, including testing and segregation of all new animals. Work closely with your veterinarian to develop a comprehensive vaccination plan tailored to your herd's specific needs. Improve hygiene and sanitation practices to reduce the spread of disease, including paying close attention to stall maintenance and manure management. Consider pasteurizing colostrum and discard milk to reduce the risk of transmitting pathogens to calves. Regularly monitor your herd for clinical signs of JD and BVD, and promptly investigate any suspected cases.
By taking a proactive approach to disease prevention and management, you can significantly reduce the risk of JD and BVD in your herd, safeguarding the health and productivity of your animals and ensuring the long-term sustainability of your dairy operation. Don't wait until it's too late – start implementing these strategies today.