Lyme disease is a disease that can affect humans as well as several animal species, including horses. Like piroplasmosis, Lyme disease is transmitted by ticks that are themselves infected with the disease. Very difficult to diagnose, this disease of the horse remains very enigmatic for the veterinary profession.
What is Lyme disease in horses?
Lyme disease is also called Borreliosis. It is already quite widespread on the French territory, especially in the north and east. It is transmitted by ticks, but also more rarely by horseflies, fleas and mosquitoes. It is therefore more present in wooded or humid regions, where horse ticks are concentrated. Still quite enigmatic, this disease has potentially already affected many horses, but most of them have remained asymptomatic. It can also occur quite a long time after the bite, which makes the diagnosis very difficult.
Symptoms of Lyme disease in horses include mild hyperthermia, lethargy, chronic wasting, difficulty swallowing, stiffness or lameness, uveitis, neurological signs (encephalitis or meningitis) or hypersensitivity to light or touch. These symptoms can be common to other pathologies, so it is very difficult to be sure that this is what your horse is suffering from.
How is Lyme disease diagnosed in horses?
Since physical symptoms are rarely enough to make a definite diagnosis of the disease, there are several tests that can show the disease, such as a serological test (ELISA test), which looks for Lyme disease antibodies in the horse’s blood. However, if the test is positive, it may mean that your horse has Lyme disease now, as well as having had it in the past, but no longer has it. This is because the horse’s antibodies to the disease can remain in its bloodstream for quite a long time. This test will therefore only give an indication of whether your horse has come into contact with this disease.
There is also a PCR test, which looks directly for the DNA of the bacteria in the horse’s blood or joint fluid. But as with the serological test, this test will not prove 100% that your horse is actually suffering from the disease.
However, it should be noted that many false-positives and false-negatives exist in these tests, so their reliability is often questioned.
How to prevent or treat Lyme disease?
To date, there is no vaccine against this disease, so prevention is difficult. The only way to fight against contamination is to spray regularly with anti tick treatment for horses when he is outside and to proceed to a regular rigorous examination on his body. This will detect any presence of ticks as soon as possible, knowing that to contaminate your animal, the tick must be present on its body for more than 24 hours.
The most common treatment is a tetracyline antibiotic, which also has anti-inflammatory properties. So if your horse shows clinical signs of improvement after antibiotics, this may also be due to the anti-inflammatory medication and in no way confirms that the diagnosis was correct.
