You are here: Home / Articles / Equestrian Life
Understanding Lyme disease
Lyme disease is passed on to horses by sheep ticks and is common in woodland areas
Passed on by the sheep tick, Lyme disease is a rare illness that is difficult to diagnose as it mimics other complaints.In 1975, a mystery illness in adults and children in Lyme, Connecticut, USA, occurred, which was subsequently recognised as Lyme disease. In 1985, the disease was first identified in horses in the USA, and the first definite case in a British horse was diagnosed in Sussex in 1993.
Lyme disease is a caused by a specialised bacteria, known as borrelia burgdorferi, and is transmitted to horses by sheep ticks. As ticks need thick vegetation in which to live, the disease is common in woodland areas.
Diagnostic difficulties
In the horse, Lyme disease can cause a variety of illnesses and mimic numerous different diseases, which makes it difficult to diagnose just by an examination. The symptoms are:
Finding antibodies
A diagnostic aid is to analyse a blood sample for specific antibodies (special blood markers) to the bacteria which cause Lyme disease. Research carried out atthe University of Liverpool has shown that many normal horses from certain areas in the UK have these antibodies. Infection appears to be common in East Anglia, around Thetford Forest, and along the south coast, near the New Forest.
In these parts of Britain, it appears that many horses have been infected with Lyme disease, but only a few appear to show any illness despite the infection. In other parts of the world, such as the USA or Scandinavia, infection seems to cause disease more commonly in the horse. This is probably due to different strains of the same bacteria being present.
Sensitive test
A more sensitive ¨ and accurate ¨ test has recently been developed, known as PCR (polymerase chain reaction). Once samples of either blood, urine or joint fluid have been taken from the horse, this test can recognise the specific bacteria which causes Lyme disease. While the test can definitely say whether the bacteria which causes the disease is present in the horse,it cannot tell us whether those bacteria are causing problems.
Since most infections with this bacteria do not cause any illness in the horse, it is still uncertain how useful the test will be in diagnosing and managing Lyme disease.
As Lyme disease can mimic numerous other diseases, and because we do not have a perfect test, diagnosis is extremely difficult. Often, diagnosis is made on the basis of the clinical signs in the sick horse, combined with a history of its exposure to ticks. The likelihood that such a horse is suffering from Lyme disease is increased by the positive results of blood tests.
Long-term treatment
Fortunately for such an unpleasant disease, affected horses can be treated easily with antibiotics. The bacteria which causes Lyme disease is sensitive to several of the antibiotics which vets generally prescribe for the horse. The only problem is that horses may have to remain on the drugs for more than a month. Sometimes, horses whichhave the arthritis form of the disease are so sore they also have to receive a painkiller. Bute is often used while the horse slowly responds to the antibiotics.
Rare disease
Lyme disease in the horse is a rare illness, withonly a few horses each year falling sick with it in the UK. Despite this, we see from blood samples that although many horses get the infection, the vast majority never show any illness. As a result, there is a danger that vague signs of other diseases may be incorrectly called Lyme disease. The presence of antibodies in a blood sample can only confirm a clinical picture. If the picture does not fit, the antibodies may be a red herring.
Avoiding infection
Unfortunately, there is no effective vaccine for Lyme disease, and the best way to avoid infection is to make sure your horse is not exposed to ticks. In certain areas of the country this can be virtually impossible, although careful grooming can identify the ticks, which can be removed, and decrease the risk of infection
Related articles:
- New welfare guide to prevent disease spread
- Does navicular syndrome still exist?
- Recession hits equine disease research
- Horse tax may be as much as £100 per horse
- Latest advice on equine diseases published for breeding industry
- Horse owners urged to oppose horse tax by signing petition
- Annual equine disease survey planned to aid horse welfare
- Horseworld petitions Defra over horse owners levy
- Horse tax plans under fire at Defra roadshows
- Horse owners urged to attend 'horse tax' meetings
Subscribe to Horse & Hound and Save
Enjoy all the latest equestrian news and competition reports delivered straight to your door every week.
Click here to subscribe now