Bovine viral diarrhea (BVD) remains one of the most economically significant infectious diseases affecting cattle worldwide. While many producers vaccinate routinely and may rarely observe dramatic outbreaks, the virus can circulate quietly within herds, reducing performance long before obvious clinical signs appear.
In both dairy and beef systems, BVD often operates below the surface. The impact is not limited to visible clinical cases – it is reflected in reproductive inefficiency, compromised immunity and greater vulnerability to secondary infections.
For producers today, the key question is no longer whether BVD exists, but whether it is truly under control within their own operation.
Understanding the role of persistently infected animals
The central driver of BVD transmission is the persistently infected (PI) animal.
When a pregnant cow becomes infected during early gestation (approximately 30-125 days), the fetus may become persistently infected. These calves:
- Shed large amounts of virus throughout their lives
- May appear clinically normal
- Do not mount an effective immune response
- Continuously expose herdmates
A single PI animal can rapidly expose a large proportion of susceptible animals in direct contact.
In dairy herds, this may translate into reproductive instability and increased health treatments. In cow-calf operations, it may result in waves of pregnancy loss or weak calves. In backgrounding and feedlot systems, exposure to PI animals can significantly increase respiratory disease incidence and treatment rates.
Identifying and removing PI animals is widely recognized as the cornerstone of effective BVD control.
The connection between BVD and respiratory disease
In the beef sector particularly, bovine respiratory disease (BRD) remains one of the most costly health challenges in young cattle.
BVD contributes to this issue through immunosuppression. The virus impairs both innate and adaptive immune responses, increasing susceptibility to viral and bacterial pathogens involved in BRD.
Common production stressors – such as weaning, transportation, commingling, weather fluctuations and pen changes – can further amplify this risk.
As a result, BVD control is not solely a reproductive issue. It is also a strategic component of respiratory disease prevention in both dairy and beef systems.
Knowing your herd status: A critical first step
Vaccination is an important tool, but it should be implemented within a structured herd health plan that includes an understanding of herd status.
Working with a herd veterinarian, producers may consider:
- Testing youngstock (9-18 months of age) for antibodies to evaluate recent viral circulation
- Bulk tank milk PCR testing in dairy herds
- Individual blood or ear-notch PCR testing for suspect animals
- Screening newborn calves in herds with known or suspected circulation
These approaches help determine whether BVD is actively circulating or whether the herd is likely free of infection.
Without surveillance, control efforts rely on assumption rather than evidence.
A practical three-pillar strategy
Effective BVD control programs are typically built on three key pillars:
1. Biosecurity
Preventing introduction of PI animals is essential.
Important considerations include:
- Testing purchased replacements
- Managing fenceline contact in pasture-based systems
- Monitoring animals returning from shows or sales
- Implementing quarantine protocols
Given the movement of cattle between operations, auctions and backgrounding facilities, biosecurity remains a critical line of defence.
2. Identification and removal of PI animals
Once identified, PI animals should be removed from the herd.
Maintaining a PI animal within the herd sustains continuous viral shedding and increases the risk of generating additional PI calves. Removal significantly reduces viral pressure and improves long-term herd stability.
3. Vaccination and ongoing surveillance
Vaccination plays an important protective role by:
- Protecting pregnant cows from fetal infection
- Reducing the risk of generating new PI calves
- Supporting herd immunity in higher-risk regions
However, vaccination alone does not replace identification and removal of PI animals.
Ongoing monitoring ensures that progress is maintained and that reintroduction is detected early.
Dairy and beef: Different systems, shared principles
Although management practices differ, the biological principles of BVD control remain consistent.
In dairy herds:
- Reproductive performance is highly sensitive to viral circulation
- Bulk tank testing can support surveillance
- Calf grouping and management influence transmission dynamics
In beef operations:
- Protecting pregnant cows is critical in cow-calf systems
- Commingling increases risk in backgrounding and feedlot phases
- Respiratory performance can be indirectly influenced by viral pressure
Each operation should tailor its approach according to herd structure, management system and regional risk.
From detection to protection
A structured approach to BVD control can be summarized in two complementary steps: detection and protection.
Detection involves understanding herd status, identifying PI animals and implementing surveillance. Protection involves strengthening biosecurity and implementing vaccination strategies within a comprehensive herd health program.
When these elements are integrated, producers move from reactive disease management to proactive herd stability.
The bottom line
BVD is a controllable disease.
Producers who implement structured control strategies may benefit from:
- Improved reproductive efficiency
- Reduced respiratory disease pressure
- Lower treatment costs
- Greater predictability in herd performance
The tools are available – diagnostics, biosecurity protocols and effective vaccines.
The difference between endemic circulation and long-term stability lies in moving from assumption to strategy.
Do you know your herd’s BVD status – or are you assuming it?
This article has been adapted for a producer audience by Rogério Eduardo de Souza Júnior, technical marketing manager – HIPRA Canada, from technical work by Dr. Camilla Luzzago, DVM, Ph.D., associate professor of animal infectious diseases, University of Milan, Italy.
This is the second article in the Detect and Protect technical series from HIPRA Canada, dedicated to advancing cattle health. We explore the causes, diagnosis and prevention of bovine respiratory disease (BRD) to empower producers with science-based insights and solutions.
