Borreliosis in Horses
(Equine Lyme Disease)
In tests for 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:
- Pyrexia - generally mild (fever)
- Lethargy (weakness / loss of energy)
- Anorexia (loss of appetite leading to weight loss)
- 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 horse's hoof)
- Uveitis (inflammation within the eye)
- Behavioural changes
- Hyperaesthesia (excessive sensitivity)
- Ataxia (loss of coordination)
Diagnosis
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.
Diagnostic Tests
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.
Treatment
Successful treatment can sometimes be problematic and clinical signs may unfortunately recur after treatment.
The treatment of choice for clinical cases is generally Tetracyclines with the recommended regime being:
1 week of I.V. Oxytetracycline @ 5mg/kg q24h or q12h, followed by
2-3 weeks PO Doxycycline @ 10mg/kg q12h.
I.M. Ceftiofur sodium (Excenel) @ 2-4mg/kg q12h has also been successful in some cases.
Diarrhoea can be a side effect of treatment but is rare.
Medical Abbreviations
I.V. |
= |
intravenous |
I.M. |
= |
intramuscular |
P.O |
= |
by mouth |
q8h |
= |
every 8 hours |
q12h |
= |
every 12 hours |
q24h |
= |
every 24 hours |
Vaccines
There are no licensed vaccines against Borreliosis for horses in the UK.
