Lyme disease

Veterinary advice should be sought before applying any treatment or vaccine.

Lyme Disease

Lyme Borreliosis, Equine Borreliosis

Lyme disease is a tick-borne, multisystemic disorder, caused by the spirochete Borrelia burgdorferi. It affects both horses and humans throughout North America, Europe, and the temperate regions of Asia. Many mammals and birds act as reservoirs for the spirochete, which is transmitted among wildlife, domestic animals, and humans, primarily by ticks of the Ixodes ricinus complex.

Lyme disease can mimic many other diseases, which makes diagnosis difficult. Lyme disease in horses has been poorly documented and is not well understood. Infected horses often vary considerably in symptoms observed, and some horses don't show any symptoms. Lyme disease is most frequently associated with musculoskeletal disorders, including laminitis, swollen joints, muscle tenderness, and lameness.

Symptoms of Lyme Disease in Horses

The typical, early clinical signs of Lyme disease include weight loss, muscular atrophy, weakness, and laminitis -related. Symptoms usually progress to generalized stiffness with gait abnormalities, intermittent lameness, reduced ability to bend neck, fever, effusion and behavioral changes. Some horses develop marked muscle wasting, ataxia, depression, and severe neck stiffness.

Diagnosis of Lyme Disease

The diagnosis of lyme disease is based on clinical signs and a history of exposure to ticks. Definite diagnosis is challenging unless ticks are found on the horse, or the horse is living in or has a history of visiting an area where infected ticks are endemic. Most cases of lyme disease occur during the spring and summer months.

Incubation Period for Lyme Disease

The incubation period for Lyme disease in horses is not known, but it is 2–5 months in dogs and can be months to years in humans.


Generalized stiffness
Intermittent lameness
Behavioral changes
Marked muscle wasting
Difficulty bending neck
Weight loss


  • History
  • Geographical area
  • Clinical signs
  • Physical exam
  • Serology
  • ELISA of serum sample
  • Immunofluorescent antibody (IFA) testing
  • Positive Western Blot of serum sample
  • PCR assay of tissue sample of tick
  • Radiographs



Supportive care


  • Vaccination with one of the several canine approved Lyme vaccines which are commonly used in horses
  • Apply insect repellents
  • Examine the horse daily
  • Keep pastures mowed
  • Reduce habitat for wild animals that host ticks


Scientific Research

General Overviews

Risk Factors

  • Grazing in pastures with long grass
  • High deer and other wildlife populations who access the same pasture horses are kept
  • Season - Most cases of lyme disease occur during the spring and summer months, when ticks are more abundant.



Causative agent