Lyme disease

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

Lyme Disease

Lyme Borreliosis, Equine Borreliosis

Lyme disease is a multisystem tick-borne disease caused by infection with the spirochete Borrelia burgdorferi. The spirochete is transmitted primarily during the blood meals of Ixodes ticks. The disease occurs worldwide, following the same pattern similar to that of humans. There has been increasing incidences of Lyme disease reported worldwide, which are suspected to be caused by migratory birds and white-tailed deer.
The density of infected ticks is the primary factor for risk of infection with Lyme disease. Horses living in the northeast, midwest, and certain areas in California have a higher risk of infection.

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.

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.

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
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


Oral doxycycline or minnocycline
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 References

Good Overviews