Lyme disease in horses

Lyme disease in horses – causes, symptoms, diagnosis and treatment

Lyme disease, also known as Lyme borreliosis , is a disease caused by the bacterium Borrelia burgdorferi that can occur in many animal species, including horses. The pathogen is transmitted primarily through the bite of ticks. In horses, the disease can lead to a variety of symptoms, ranging from minor discomfort to serious health problems. Because the symptoms are often nonspecific and develop slowly, diagnosis is not always easy, and the disease is often not recognized immediately.

In this blog post, we give you a comprehensive overview of Lyme disease in horses – from the causes and symptoms to diagnosis, treatment, and prevention.

What is Lyme disease and how is it transmitted?

Lyme disease is a bacterial infection caused by the bacterium Borrelia burgdorferi . It is a spirochete bacterium transmitted to horses and other animals by ticks of the genus Ixodes (commonly known as the "black wood tick"). These ticks pick up the bacterium when they feed on an infected animal (e.g., a deer or a rodent). If a tick then bites a horse, it can transmit the bacterium.

Transmission does not occur immediately, but only after a certain period of feeding. The tick usually has to feed on its host for several hours to days to transmit the bacteria to the horse. Therefore, it is important to detect tick bites early and remove the ticks promptly to reduce the risk of Lyme disease transmission.

Symptoms of Lyme disease in horses

Lyme disease in horses can lead to a variety of symptoms, which are often insidious and non-specific. In many cases, the disease does not become apparent until weeks or months after the tick bite. The most common symptoms include:

General symptoms

• Lameness : One of the most common clinical manifestations of Lyme disease is lameness, which frequently occurs in the limbs. It is particularly noticeable that the lameness often occurs in bouts and can worsen depending on the load.

• Stiffness and joint pain : Horses with Lyme disease often exhibit general stiffness, especially when standing or beginning to move. They may also be sensitive to pressure in the joints.

• Fever : In some cases, fever may occur, indicating an acute infection.

Skin and coat changes

• Hair loss and skin irritation : Some horses develop skin problems, such as hair loss or skin irritation, due to inflammation caused by the bacterial infection.

Nervous and behavioral changes

• Behavioral changes : Lyme disease can also affect behavior. Horses may appear unusually nervous or irritable, especially when touching affected areas.

• Incoordination disorders and paralysis : In severe cases, neurological symptoms such as incoordination disorders or even partial paralysis may occur. However, these symptoms usually only appear in advanced cases.

Chronic complaints

In chronic cases, Lyme disease can lead to persistent discomfort such as persistent lameness and joint pain, which can be confused with other diseases. The horse may have increasing difficulty performing normal movements.

Diagnosis of Lyme disease in horses

Diagnosing Lyme disease in horses is often difficult because the symptoms are nonspecific and can be confused with other diseases. However, there are several diagnostic procedures that can confirm a Lyme infection :

Clinical examination

The veterinarian will first perform a thorough clinical examination, looking for typical signs of Lyme disease. This includes observing lameness, stiffness, and possible joint pain. The veterinarian will often also check for tick bites or tick remains to increase the likelihood of Lyme disease infection.

Serological tests

A common method for diagnosing Lyme disease is a blood test . This involves testing the horse's blood for antibodies against the Borrelia bacteria. These antibodies are produced when the horse's immune system reacts to the infection. A positive test indicates that the horse has come into contact with the bacteria, but does not necessarily mean that it is actually infected.

PCR test

The PCR (polymerase chain reaction) test can be used to detect the presence of the Borrelia bacterium directly in blood or tissue samples. This test is particularly useful in cases of acute infection.

Husbandry and environmental factors

To assist with the diagnosis, the veterinarian will also consider the horse's housing conditions, particularly the frequency of tick bites and the animal's habitat. Horses kept in tick-dense areas are at higher risk for Lyme disease.

Treatment of Lyme disease in horses

Treatment of Lyme disease in horses should begin as early as possible to alleviate symptoms and prevent long-term damage. Treatment typically includes the following measures:

Antibiotic therapy

Antibiotic therapy is the main treatment for Lyme disease. Commonly used antibiotics are doxycycline or amoxicillin , which are effective against Borrelia burgdorferi . Treatment typically lasts several weeks and can vary depending on the severity of the infection. The horse must be closely monitored during antibiotic administration to avoid side effects and ensure the effectiveness of the treatment.

Pain treatment and anti-inflammatory

Since Lyme disease is often associated with severe joint and muscle pain, the veterinarian will also prescribe painkillers and anti-inflammatory medications . These help relieve discomfort and improve the horse's mobility. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as phenylbutazone are commonly used.

Support of the immune system

In some cases, it may be beneficial to support the horse's immune system , especially if the animal suffers from chronic symptoms. Vitamin supplements , minerals , or immune stimulants can be used for this purpose.

Symptomatic treatment

In addition to antibiotic treatment, symptomatic relief measures are often used. These include physiotherapy, such as gentle stretching exercises and muscle strengthening, as well as the application of heat or cold treatments to relieve joint pain.

Prevention of Lyme disease

Prevention of Lyme disease in horses primarily focuses on protection against tick bites . Here are some helpful preventative measures:

• Tick ​​prevention : Use tick repellents suitable for horses. These products can be applied to the coat as sprays, shampoos, or powders and provide protection against tick bites.

• Regular tick checks : Especially after being outdoors, your horse should be checked regularly for ticks and removed promptly.

• Tick ​​reduction in the stable environment : Ensure that the stable and pastures are regularly maintained to minimize tick populations. Regular pasture maintenance (e.g., by mowing the grass and removing overgrowth) can also help reduce the risk of tick bites.

• Vaccination : There is currently no specific vaccine against Lyme disease for horses. A tick vaccination for dogs already exists, but this option is not yet available for horses.

Lyme disease is a serious disease in horses that can be accompanied by various symptoms, from lameness to neurological disorders. Early diagnosis and targeted treatment are crucial to relieving the horse of symptoms and preventing long-term damage. Preventive measures, such as tick protection and regular tick inspections, are important.

Source; Martina Hemm July 2025