Deer and Bovine Tuberculosis: Understanding the Risks for Livestock and Wildlife

Bovine tuberculosis (bTB) is a serious disease affecting cattle herds across the UK. While badgers are the most well-known wildlife reservoir for bTB, deer are also part of this complex picture. In this blog post, we’ll explore how deer can play a role in bTB dynamics, the implications for farmers and landowners, and the steps that can be taken to manage these risks.

What is Bovine Tuberculosis?

Bovine TB is caused by the bacterium Mycobacterium bovis. It primarily affects cattle, but a wide range of other mammals, including deer, can also become infected. In livestock, bTB can lead to:

• Weight loss and poor condition
• Chronic coughing
• Reduced milk production and fertility

For farmers, a bTB outbreak means significant economic and emotional stress, as herds are subjected to movement restrictions and compulsory testing, and infected animals must be culled.

How Can Deer Become Infected?

Deer are known to be susceptible to bTB infection, and in some parts of the UK, particularly areas with high bTB prevalence in cattle, deer have tested positive for the bacterium.

Deer can become infected through:

• Direct contact with infected cattle or other deer
• Ingestion of contaminated feed or water sources
• Environmental contamination in shared pastures

Once infected, deer can potentially spread the bacteria within their populations and, in rare cases, back to cattle. However, deer are generally considered a “spillover” host, meaning they acquire the infection from cattle rather than sustaining it independently like badgers can.

Regional Differences in Deer and bTB

The role of deer in bTB transmission varies across the UK:

• In most areas, deer are not considered a significant reservoir of infection.
• In certain high-prevalence areas (such as parts of the South West of England), studies have found evidence of bTB in wild deer populations.
• Red deer and fallow deer are more likely to be involved in these areas, as their movements and interactions with cattle overlap more closely.

This means that while the overall risk of deer spreading bTB to cattle is lower than that posed by badgers, it remains a concern in specific regions.

Implications for Farmers and Landowners

For farmers in high bTB-risk areas, understanding the local wildlife picture is important. Deer can contribute to the persistence of bTB in the environment, and this can make it more difficult to eradicate the disease from cattle herds.

Farmers and landowners who manage land where deer and cattle interact should be aware of:

• Signs of poor health in deer populations, including weight loss, respiratory issues, or unusual behaviour
• Shared water sources and feeding areas that could facilitate indirect transmission
• The importance of biosecurity measures to limit contact between wildlife and livestock

Managing Risks and Supporting Healthy Populations

There are practical steps that can help reduce the risks of bTB transmission between deer and livestock:

• Good fencing and field boundaries: Preventing direct contact where possible.
• Water source management: Ensuring livestock have clean, uncontaminated water supplies.
• Pasture management: Rotating grazing and managing shared areas carefully.
• Deer management: In areas with high deer populations, regulated culling or working with local deer management groups can help reduce density and disease risk.

Government agencies and organisations like the British Deer Society and National Farmers’ Union provide guidance on managing these risks in line with best practice and animal welfare considerations.