BVD in cattle is a highly contagious infectious disease caused by the Bovine Viral Diarrhea Virus (BVDV), which can affect healthy cattle and cause severe health complications for both adult cattle and newborn calves. The disease impacts cattle populations, causing reproductive losses, respiratory disease, gastrointestinal disorders, and more. Managing BVD in cattle requires an understanding of its symptoms, prevention strategies, and treatment options to safeguard pregnant females, prevent fetal infections, and control the spread of the virus in the herd.

What is BVD in Cattle?

BVD in cattle refers to an infection caused by the Bovine Viral Diarrhea Virus (BVDV), which leads to two types of infections in cattle: acute infection and persistent infection (PI). PI animals, or persistent infection cattle, are born with the virus, making them lifelong carriers and shedding large amounts of virus into their environment. This significantly contributes to the infection of cattle within the herd.

Infected cattle can also develop clinical disease, which presents as various symptoms, including viral diarrhea virus infection (leading to bloody diarrhea), respiratory diseases, and enteric diseases. The virus can cause digestive tract diseases in cattle, leading to reduced weight gain, severe discomfort, and in some cases, fatal disease.

Key Symptoms of BVD in Cattle

Symptoms of BVD in cattle vary depending on the type of infection, and recognizing these signs of disease early can help reduce the impact on herd health. The disease can manifest as either acute infection or persistent infection (PI), with different consequences.

Symptoms of Acute BVD Infection

In cases of acute BVD infection, cattle may show the following:

• High fever and mild disease symptoms such as lethargy
• Bloody diarrhea or severe diarrhea leading to dehydration
• Nasal discharge and coughing, indicative of respiratory disease
• Weight loss and reduced appetite
• Signs of disease affecting the digestive tract, leading to poor nutrient absorption

Symptoms of Persistent BVD Infection (PI Animals)

PI animals, which are infected in utero during fetal infection, are born with the virus and may appear normal at birth. However, these animals continuously shed the virus into the herd, spreading BVD throughout the population. PI animals can eventually show chronic symptoms, including:

• Poor growth and development
• Respiratory disease and enteric diseases
• Recurrent infections of cattle, including secondary respiratory diseases or other mixed infections

BVD in Cows and Calves

BVD in cattle affects pregnant cattle and newborn calves differently, with distinct health risks associated with each.

BVD in Cows: Reproductive Losses and the Reproductive Tract

In pregnant females, BVD can result in reproductive losses, including abortions, stillbirths, and birth defects in newborn calves. The virus infects the reproductive tract, leading to fetal infections and potentially the birth of PI animals. Cows may also experience infertility, further complicating herd reproduction. Maternal antibodies may offer some protection to calves in the first few weeks after birth, but they do not prevent BVD infection from a primary infection or acute infection.

BVD in Newborn Calves: Signs and Risk Factors

For newborn calves, BVD poses significant risks, including:

• Fatal disease caused by severe clinical disease
• Bloody diarrhea and dehydration due to gastrointestinal infections
• Respiratory disease due to viral infections
• The potential for reproductive losses in calves born to infected cattle

The Role of Viral Vaccines in Preventing BVD

Vaccination is an essential tool in preventing the spread of BVD in cattle. Viral vaccines protect healthy cattle from both acute infections and persistent infections (PI animals). The use of MLV BVDV vaccines (Modified Live Virus) has been shown to reduce the impact of BVD, including the occurrence of reproductive losses and respiratory diseases.

Vaccinating all cattle, including pregnant cattle, helps to protect newborn calves from infection, as maternal antibodies may provide passive immunity to protect against the virus in the early stages of life. Viral vaccines should be administered regularly, particularly to herds with a higher risk of infection of cattle or those with closed herds.

Diagnosing BVD in Cattle

BVD in cattle is diagnosed through a combination of clinical observation and laboratory testing. Early diagnosis is crucial in controlling the spread of the virus, especially in closed herds.

Laboratory Testing for BVD

PCR testing and other diagnostic methods like virus isolation are used to detect the presence of BVDV. These tests can identify PI animals who may not show visible symptoms but are chronic carriers of the virus. Testing helps identify infected cattle early, enabling farmers to implement control measures like ear notches or other quarantine methods to reduce the spread.

Treatment of BVD in Cattle

While there is no cure for BVD in cattle, supportive treatment can help alleviate symptoms and prevent secondary infections. Treatment focuses on improving the overall health of affected cattle and managing the clinical signs of disease.

Supportive Care for BVD-Infected Cattle

Cattle suffering from BVD may require the following treatments:

• Hydration therapy to prevent dehydration due to diarrhea
• Antibiotics to treat secondary infections like respiratory diseases or enteric diseases
• Anti-inflammatory drugs to reduce fever and discomfort
• Nutritional support to improve overall health and recovery

Managing PI Animals

The most effective way to manage PI animals is through culling, as these animals continuously shed large amounts of virus, affecting the herd’s health. Preventing the birth of PI animals through vaccination of pregnant females is key to controlling the disease within the herd.

Preventing BVD in Cattle

Preventing BVD in cattle requires an integrated approach, including vaccination, maintaining a closed herd, and implementing strict biosecurity measures to avoid the introduction of infected cattle.

Vaccination and Biosecurity Measures

The use of viral vaccines, such as MLV BVDV, is the primary method for preventing BVD. Ensuring that all cattle are vaccinated—particularly pregnant cattle and newborn calves—reduces the risk of fetal infections and limits the spread of the virus. Additionally, biosecurity measures such as quarantining new animals and controlling movement within the herd are essential for maintaining a healthy herd and preventing mixed infections.

The Economic Impact of BVD in Cattle

BVD in cattle leads to significant economic losses, primarily due to reproductive losses, secondary infections, and the ongoing need for treatment. The presence of PI animals in a herd can result in long-term economic damage, making early diagnosis and control strategies critical.

Related FAQs

References:

• Bovine Viral Diarrhea Virus – CDC
• BVD in Cattle – Disease Management
• Preventing BVD in Cattle – Vaccination Strategies

Next Steps: For more information on side effects and safety considerations, visit our article on Side Effects and Safety of BVD Vaccines in Cattle.