Dairy herd with a cloud formation symbolizing hidden disease threats.

Is Your Herd at Risk? Unveiling the Hidden Threats of Johne's Disease and BVD

Lena Kashyap in Health & Wellness December 2025 • 6 min read.

"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.

What Does the Research Say About Disease Prevalence?

Dairy herd with a cloud formation symbolizing hidden disease threats.

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.

Researchers visited 22 farms that had tested positive for JD and/or BVD to gather detailed information on their management practices. The average herd size on these farms was considerable, with 778 milking cows. The average milk production was 20,052 lbs (9240 kg), and somatic cell counts (SCC) averaged 175,545/ml. A significant percentage of stalls were visibly soiled (37%), an indicator of potential hygiene issues.

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.

Alarmingly, the study found that a significant number of farms lacked basic biosecurity measures when introducing new animals. A high percentage (64%) did not perform any disease testing or segregation of replacement animals. Even among farms that did implement some biosecurity practices, the most common measure was a 9-way vaccine, including BVD, upon arrival (27%), with only a small percentage segregating replacements or testing for specific diseases. Furthermore, the percentage of farms that would identify known positive cows was 67%. Producers also reported that around 57% of known JD-positive cows were allowed to calve again. No producers had separate calving areas for either JD or BVD-positive cows.

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?

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.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.4172/2157-7579.1000240, Alternate LINK

Title: Dairy Herd-Level Prevalence Of Johne'S Disease And Bvd In The Intermountain West Of The U.S.A. And Farm Management Practices And Characteristics For Test-Positive Herds

Subject: General Veterinary

Journal: Journal of Veterinary Science & Technology

Publisher: OMICS Publishing Group

Authors: David J Wilson

Published: 2015-01-01

Everything You Need To Know

What are Johne's Disease and Bovine Viral Diarrhea and what impact do they have on dairy herds?

Johne's Disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), leads to chronic digestive issues, impacting weight and milk production, and sometimes results in culling. Bovine Viral Diarrhea (BVD) causes reproductive and respiratory problems, leading to financial losses for dairy farmers. A significant percentage of farms lacking testing or segregation protocols when introducing new animals highlights a critical biosecurity gap that elevates herd risk. Without testing or segregation, infected animals can unknowingly introduce or spread diseases within the herd, leading to outbreaks and economic losses. Testing, however, doesn't completely rule out the presence of disease within the herd.

What does the study suggest about how common Johne's Disease and Bovine Viral Diarrhea are in dairy farms?

The study revealed that 38% of dairy farms tested positive for Johne's Disease (JD), and 9% tested positive for Bovine Viral Diarrhea (BVD). Approximately 3% of farms had both diseases. This indicates a significant presence of these diseases in dairy herds, highlighting 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.

Based on the research, what management practices increase the risk of Johne's Disease and Bovine Viral Diarrhea?

Key risk factors include a lack of biosecurity measures for introducing new animals, such as not performing disease testing or segregation of replacement animals. Visible soiling in stalls (37% in the study) indicates potential hygiene issues that can contribute to disease transmission. Allowing known Johne's Disease (JD)-positive cows to calve again and the absence of separate calving areas for infected cows also increase the risk of spreading the disease. Even though 27% use a 9-way vaccine, including BVD, upon arrival, it may be the only biosecurity farms use.

What steps can dairy farmers take to protect their herds from Johne's Disease and Bovine Viral Diarrhea?

Implementing robust biosecurity protocols when introducing new animals is crucial. This includes testing and segregating replacement animals to prevent the introduction of Johne's Disease and Bovine Viral Diarrhea into the herd. The most common measure was a 9-way vaccine, including BVD, upon arrival (27%), with only a small percentage segregating replacements or testing for specific diseases. While not examined in this study, regular monitoring of herd health and maintaining high standards of hygiene in housing and calving areas is also recommended.

What signs should dairy farmers look for in their cows that might indicate Johne's Disease or Bovine Viral Diarrhea?

Clinical signs of Johne's Disease (JD) observed on affected farms included adult cows becoming thin despite maintaining a good appetite (81%) and adult cows contracting diarrhea and dying (52%). Farms with Bovine Viral Diarrhea (BVD) reported instances of abortions. These clinical signs, while not definitive, can serve as early warning signs, prompting further investigation and testing to confirm the presence of these diseases and implement timely control measures. Early detection allows for quicker intervention, reducing the risk of widespread infection and economic losses.