Louping Ill Cases Detected in the Scottish Borders

 

Louping Ill has not been diagnosed in the Scottish borders since 2003. However it has been diagnosed at St Boswells on two separate — but geographically close — farms in recent weeks. The presentations were different and worthy of note so that further cases are not misdiagnosed.

Given that there have been no confirmed cases in the region for over two decades, these cases highlight the need for increased vigilance and vets should be giving the disease consideration in their diagnostics.

What is Louping Ill?

Louping Ill is a tick-borne flavivirus affecting sheep, but also known to cause disease in cattle, red grouse, and humans. While the classic clinical hallmark is hypermetria (a neurological condition, often associated with cerebellar dysfunction, where voluntary movements overshoot their intended target), it’s important to recognise that signs can be variable — including recumbency, seizures, or even sudden death.

Case 1: The ‘Classic’ Presentation in Cheviot Hoggs

The first outbreak involved homebred Cheviot hoggs grazing a tick-infested rough hill area. These animals exhibited neurological signs, progressing from hyper-reactivity to seizures.

Two hoggs were submitted alive to Greycrook for post-mortem. Diagnosis was confirmed through:

• Serology (positive Louping Ill antibodies)
• PCR
• Histopathology

Interestingly, both hoggs also tested positive for Tick Borne Fever (TBF), likely exacerbating immunosuppression and disease progression.

Case 2: An Atypical and Easily Misdiagnosed Presentation

The second case involved 4-week-old lambs born to recently purchased ewes. Although the adult ewes were clinically unaffected, several lambs in the group became progressively weak and died. Clinically, one lamb appeared to have hindlimb paralysis, presenting very similarly to a spinal abscess.

Post-mortem and laboratory work confirmed:

• Non-suppurative encephalomyelitis, characteristic of Louping Ill
• Louping Ill virus by confirmatory testing.

This case is a reminder: naive bought-in dams may not provide colostral immunity, leaving lambs vulnerable to LIV in early life.

Preventing Louping Ill

Currently, no commercial vaccine for Louping Ill is available, though the Moredun Institute is in the process of developing one and is seeking crowdfunding for commercialisation.

Until then, tick control and strategic acclimatisation remain our best tools:

• Use of pour ons containing cypermethrin
• Grazing management to avoid high-risk tick habitats
• Exposure of naive animals to low-level challenge pre-breeding season where appropriate.

Environmental Factors

A changing landscape is increasing the tick threat:

• More suitable tick habitat due to local land-use changes
• Woodland edges and deer-favoured grazing areas show especially high tick burdens
• Climate warming is enabling ticks to complete two life stages in one year, boosting population numbers.

Other Tick-Borne Viruses

It’s not just Louping Ill we need to worry about. In recent months, we’ve seen:

• Tick Borne Fever
• Tick Pyaemia
• Babesiosis.

This underscores the need for robust tick control programs and increased awareness of tick-associated disease presentations in both young and adult stock.

Key Takeaways for Vets

• Maintain clinical suspicion for Louping Ill in any neurological presentation in sheep, especially in tick-risk areas.
• Consider it a differential in cases mimicking spinal lesions or unexplained perinatal losses.
• Educate clients on the importance of tick control and the risks associated with buying-in naive stock to higher risk areas.
• Support and share Moredun’s vaccine initiative where possible.

If you have any questions about Louping Ill Virus or suspicions you may be seeing affected animals and would like advice, please contact our Veterinary Services team to speak to one of our Veterinary Investigation Officers.

Posted by SRUC Veterinary Services on 10/06/2025