Equine Lyme Disease: Welfare and Diagnosis Challenges

Lyme disease in horses presents diagnostic and welfare challenges, with variable clinical signs ranging from subtle behavioural changes to severe neurological impairment.

Key Facts

Lyme disease is caused by the spirochete bacteria Borrelia burgdorferi, transmitted by Ixodes ticks.
Horses in tick-endemic areas of the northeastern US and parts of Europe have high exposure rates.
Clinical signs are variable and non-specific: stiffness, shifting leg lameness, sensitivity to touch, and behavioural changes.
Neuroborreliosis (neurological Lyme) can cause ataxia, cranial nerve dysfunction, and encephalitis.
Diagnosis is complicated by the high background seropositivity in endemic areas.
The C6 ELISA test helps distinguish active infection from previous exposure in some cases.
Treatment with doxycycline or minocycline for 30 days is the standard approach.
Prevention relies on tick control using appropriate repellents and environmental management.

Welfare Considerations

Lyme disease causes chronic, often poorly defined suffering in horses. Animals with persistent joint pain and stiffness may show subtle behavioural changes — reluctance to work, irritability under saddle, reduced performance — that owners and vets struggle to attribute to a specific cause. The diagnostic difficulty means horses may go through multiple lameness evaluations before Lyme is considered. Neurological Lyme causes profound welfare impact including ataxia and cranial nerve deficits. Horses with sensitivity to touch or saddle fitting pain may be disciplined for behaviour that is actually a pain response, compounding their suffering. Raising awareness of Lyme disease as a welfare-significant condition in equine practice is essential.

What You Can Do

Use effective tick preventive products and check horses daily for ticks in endemic areas.
Remove ticks promptly with fine-tipped forceps — proper removal within 24-36 hours reduces transmission risk.
If your horse shows unexplained stiffness, behavioural changes, or performance decline, discuss Lyme testing with your vet.
Use a C6 ELISA test rather than whole-cell ELISA for more accurate diagnostic interpretation.
Follow the full treatment course and retest at 6 months to assess treatment response.
Manage pasture vegetation to reduce tick habitat around areas of horse activity.