Borreliosis (Lyme Disease): Horses

(Equine Lyme Disease)

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Borreliosis (Lyme disease)

Equine Borreliosis (Lyme Disease): 

Borreliosis in horses – High rates of seropositivity have been recorded from many regions of the UK and clinical cases certainly occur in a percentage of animals. 

Clinical Signs & Symptoms vary and include:

Behavioural changes and spooking 

Pyrexia  – generally mild fever and often overlooked 

Lethargy –  weakness and/or loss of energy 

Anorexia – loss of appetite leading to weight loss and loss of condition

General stiffness / lameness 

Myalgia –  muscle soreness 

Synovial effusions – excessive synovial fluid in joints 

Laminitis – inflammation of the sensitive plates of soft tissue (laminae) in the hoof 

Hyperaesthesia – excessive sensitivity to touch and sound 

Ataxia – loss of coordination

Uveitis- inflammation of the eye,moon blindness, periodic ophthalmia

Making a definitive diagnosis can be problematic. Current laboratory support which involves finding a positive Borrelia antibody titre in horses with suspicious clinical signs has several limitations. Animals can take up to 3 months to seroconvert following infection and therefore many early cases will prove seronegative. Another problem is that the animal may become infected and seroconvert without showing any clinical signs. Animals may also remain seropositive for a very long time following treatment, which makes it difficult to determine whether a successful resolution has been achieved.

The C6 ELISA (which targets the membrane protein V1sE) is usually the initial screening method of choice. In experimental infections, animals became seropositive within 3-5 weeks of infection and BEFORE presenting clinical signs. In successfully treated animals, antibody titres waned more rapidly than with other test methods. N.B. This may still take several months. 

See research –


There are no licensed vaccines against Borreliosis for horses in the UK.

Information from-

The Liphook Equine Hospital and Laboratory – Lyme Disease in Horses

VETTIMES – Equine tick-borne disease in the UK