Lyme Disease in Horses 2025: Vet‑Approved Diagnosis, Treatment & Prevention

By Dr Duncan Houston BVSc 🩺

Lyme disease, caused by the bacterium Borrelia burgdorferi, is transmitted by Ixodes ticks and increasingly recognized in horses across North America and Canada in 2025. Clinical signs vary from subtle stiffness to severe neurologic disease. This guide empowers horse owners with veterinary insights on how to identify true disease, avoid misdiagnosis, administer effective treatment, and implement practical prevention. 🐴

1. How Common Is Equine Lyme Disease?

Although many horses test antibody-positive due to exposure, only ~5–10 % display clinical signs :contentReference[oaicite:3]{index=3}. In endemic areas (Northeast and Pacific Northwest), antibody prevalence can exceed 45 % :contentReference[oaicite:4]{index=4}. Therefore, diagnosis must focus on correlation between symptoms and lab evidence.

2. How Horses Become Infected

Ixodes ticks acquire the bacteria from wildlife and pass it through bites to horses. Horses are dead-end hosts—they cannot spread the disease :contentReference[oaicite:5]{index=5}. Susceptible season is April–October; risk rises with exposure during turnout in brushy or wooded areas.

3. Recognizing Clinical Signs ⚠️

Signs are variable and often nonspecific. Key signs include:

• Shifting-leg lameness, joint swelling & stiffness :contentReference[oaicite:6]{index=6}
• Muscle soreness, poor performance, weight loss, lethargy, low-grade fever :contentReference[oaicite:7]{index=7}
• Behavioural changes, skin sensitivity, laminitis, neurological signs (e.g., encephalitis, uveitis) :contentReference[oaicite:8]{index=8}

Neurological signs are less common but serious. Many infected horses show no outward symptoms :contentReference[oaicite:9]{index=9}.

4. Accurate Diagnosis 🔬

Confirming Lyme disease requires:

1. Compatible clinical signs
2. Serology via Multiplex Lyme assay showing recent infection markers :contentReference[oaicite:10]{index=10}
3. Preferably PCR detection of Borrelia DNA in blood or cerebrospinal fluid for neuro cases
4. Ruling out other causes (EPM, arthritis, tying-up, PHF, etc.) :contentReference[oaicite:11]{index=11}

A positive antibody test alone, without signs, is insufficient :contentReference[oaicite:12]{index=12}.

5. Treatment Approach 💊

Antibiotic Therapy

Reliable options include:

• IV Oxytetracycline – often used for severe or neurologic cases :contentReference[oaicite:13]{index=13}
• Oral Doxycycline or Minocycline – used for milder or outpatient cases; duration often several weeks :contentReference[oaicite:14]{index=14}

The exact protocol varies—veterinary guidance based on symptom severity, phase, and concurrent illness is essential.

Supportive Care

• NSAIDs for pain relief
• Joint support if needed
• Physical rehabilitation for neurologic patients

Most horses improve with treatment, though chronic cases have more guarded outcomes.

6. Prognosis 📝

Early-treated cases often resolve well. Chronic or neurologic cases require longer recovery—with intensive rehab and owner care—and may not fully recover. Persistent antibody presence post-treatment is common but doesn’t indicate ongoing disease :contentReference[oaicite:15]{index=15}.

7. Preventing Lyme Disease 🛡️

Tick Control Strategies

• Use equine-safe repellents and insect growth regulators
• Maintain pastures—keep grass trimmed, clear tall weeds and brush
• Remove leaf litter and woodpiles near turnout
• Use manure management and drainage to reduce tick habitat
• Inspect daily and remove attached ticks promptly

Emerging Options: Vaccines

No Lyme vaccine is approved for horses in the U.S., though canine vaccines are sometimes used off-label. Experimental recombinant OspA vaccines show potential but remain unavailable and unapproved :contentReference[oaicite:16]{index=16}.

8. Herd Management & Monitoring

• Track any unexplained lameness or neurological issues—consider Lyme differential
• Use Multiplex testing for suspect horses
• Don’t treat horses without clinical signs and consistent serology
• Educate handlers to watch for shifting-leg lameness and subtle behavioral change

9. Summary Table

10. Ask A Vet Support 📲

With Ask A Vet, you get:

• 🧪 Help interpreting multiplex serology and timing of PCR testing
• 📋 Guidance on antibiotic choice and treatment plans
• 🌱 Customized tick control and pasture management strategies
• 📆 Monitoring protocols for chronic or post-treatment horses
• 🧠 Rehabilitation and follow-up plans for neurologic cases

Final Thoughts 🌿

Lyme disease in horses presents a diagnostic and management challenge in 2025—but with evidence-based protocols, it’s often treatable. Focus on linking clinical signs with testing before treating, catch cases early, and protect your herd with smart tick control. Work closely with your vet to ensure accurate diagnosis, effective treatment, and optimized pasture health.

Need help diagnosing suspected Lyme cases, interpreting tests, or designing a prevention plan? Download the Ask A Vet app or visit AskAVet.com to connect with Dr Duncan Houston and equine health experts. 🐴✨

Disclaimer: This article is for educational purposes only and does not replace professional veterinary care. Always consult your veterinarian for specific health concerns.