Conditions
Lyme disease in horses: recognise the symptoms
Lyme disease is more common in horses than many owners realise. The bacterium Borrelia burgdorferi, transmitted by ticks, can cause a wide range of complaints in horses — from vague lameness to serious joint problems. The tricky part is that the symptoms closely resemble those of other conditions, meaning Lyme disease is often recognised late. In this article you will find out which signs to watch for, when to call the vet, and how to keep track of your findings in your horse's EquiSight profile.
Published: 5/24/2026
EquiSight Editorial
Redactie · EquiSight · SaFleu Equestrian Centre BV
How does a horse contract Lyme disease?
Ticks are active in the Netherlands from March through November, with peak activity in April–June and August–October. A horse is at greatest risk in areas with tall grass, woodland edges and heathland — think the Veluwe, the Utrechtse Heuvelrug and the Achterhoek. The tick bite itself is rarely noticed, as ticks on horses typically attach in the armpit, groin, neck or beneath the mane. The bacterium is only transmitted after 24 to 48 hours of attachment, so checking your horse regularly significantly reduces the risk of infection. Not every horse that is bitten will develop symptoms: some seroconvert without any visible illness.
Early symptoms to watch for
The first signs of Lyme disease in horses are vague and appear gradually. As a result, they are easily dismissed as 'a bad day' or muscle soreness after exercise. Pay particular attention to:
- Intermittent or unexplained lameness, often affecting multiple limbs at once
- Increased sensitivity when touching the back, neck or limbs
- Reduced performance and faster fatigue during riding
- Unusual behavioural changes, such as irritability or withdrawal
- Mild fever (above 38.5 °C) and general lethargy
Later and more serious complaints
When Lyme disease is left untreated, complaints can worsen and affect multiple organ systems. In an advanced stage, horses may sometimes show:
- Visible joint inflammation with warm, swollen joints
- Neurological signs: coordination problems, stumbling or ataxia
- Eye inflammation (uveitis), recognisable by a cloudy or reddish iris
- Weight loss despite normal feed intake
- Muscle wasting, particularly visible in the hindquarter muscles
Distinguishing Lyme disease from other conditions
Lyme disease is sometimes called 'the great imitator' because its symptoms overlap strongly with other common equine conditions. Lameness and back complaints can also indicate laminitis, kissing spines or muscle damage. Uveitis can occur without a Lyme infection. Behavioural changes are sometimes incorrectly attributed to training errors or character traits. That is precisely why it is so valuable to keep a structured record of symptoms. In your horse's EquiSight profile you can add dated notes, giving the vet a clear picture of how things have progressed over time. This significantly speeds up diagnosis.
When should you call the vet?
Contact a vet straight away if your horse shows two or more of the above symptoms, especially after an active tick season or a stay in a high-risk area. The vet can take a blood sample for a C6 antibody test or a Western Blot. Bear in mind that a positive result only shows that the horse has been exposed to the bacterium; an active infection is only diagnosed when clinical symptoms are present as well. Use the EquiSight calendar to schedule appointments and link results to the horse's profile.
Prevention: how to reduce the risk
- Check your horse daily for ticks, paying extra attention to the armpits, groin and neck area
- Remove ticks as quickly as possible using a tick remover — never squeeze or twist
- Use an approved tick-repellent product; ask your vet about horse-friendly options
- Avoid tall grass and woodland edges during peak periods in spring and autumn
- Record tick bites and locations in the EquiSight horse profile for a complete health overview