Lyme disease in dogs: symptoms, antibodies and treatment

Overview

Borrelia burgdorferi sensu lato is a group of several closely related bacterial species. The main species associated with Lyme disease in animals is Borrelia burgdorferi sensu stricto. The importance of other group members in causing symptomatic animal disease is less clear. The familiar pattern in humans should therefore not be directly applied to dogs.

In a northern European study of healthy dogs published in 2014, just over 2% of the mainland group had antibodies. In the island population, the proportion was 20%. Of dog samples submitted to an authority laboratory in the same region during 2000–2019, nearly 6% were antibody-positive. These figures describe exposure and selected dogs tested, rather than current clinical disease across the dog population.

A northern European study published in 2023 also found Borrelia in ticks removed from pets. There were 342 examined ticks collected from dogs and cats. Of these, 36, or 10.5%, carried B. burgdorferi sensu lato. This describes the ticks tested and cannot directly estimate infection risk for every dog walking outdoors.

Causes

A tick acquires the bacterium by feeding on an infected animal. Small rodents particularly maintain Borrelia in nature. In Europe, important vectors are the castor bean tick, Ixodes ricinus, and taiga tick, Ixodes persulcatus. The bacterium enters the bite site in tick saliva.

Transmission can begin after 16–24 hours of attachment. It often occurs after 36–48 hours of feeding. Another commonly cited estimate is at least 24–48 hours. These times are not safe waiting limits; remove a tick promptly when found. Early removal reduces the likelihood of infection.

The bacterium may initially remain in skin and later spread to other tissues. Signs can involve joint inflammation. The severe kidney syndrome is suspected to involve immune complexes deposited in the kidney filters. However, a direct causal link between Borrelia and this kidney injury has not been conclusively established.

Borrelia does not pass to dogs through insect bites, saliva or bite wounds from another dog.

Risk factors

Risk chiefly depends on exposure to infected ticks. Long grass, woodland edges and leaf litter increase opportunities for tick contact. Location alone does not determine risk, as Borrelia levels in ticks vary over time and between places.

Ticks can also be active in winter if the temperature rises above about 4 °C. Calendar month alone is therefore insufficient for assessing protection needs. The kidney syndrome associated with Borrelia has been considered more common in young and middle-aged retrievers. This does not mean every kidney disease in retrievers is due to Borrelia. Reinfection is possible even after previous exposure.

Typical symptoms

Most exposed dogs remain symptom-free. Typical onset is estimated either at 2–5 weeks or 2–5 months after a bite. A long delay can make the connection difficult to notice. Common signs include:

• Intermittent lameness shifting between legs.
• Fever and greater tiredness than usual.
• Reduced appetite.
• Swollen or clearly tender joints.
• Enlarged lymph nodes.

Signs may ease or disappear between episodes. Several joints can be inflamed at once. Dogs do not usually develop the expanding ring-shaped rash typical in humans.

Lameness can affect one or several joints. Muscle pain can also occur. Swelling may be found in a limb's soft tissues.

Complications and consequences

The rare kidney syndrome involves protein loss into urine. Kidney injury can be acute or chronic. Severe disease may cause swelling and blood clots. Blood pressure may also rise. The outlook is poor, and many affected dogs die. This differs from the course of ordinary joint disease that responds to treatment.

Signs of kidney injury visible at home include vomiting, refusal to eat and increased drinking. Weight loss and marked tiredness may occur too. However, a positive Borrelia test is insufficient to identify the cause of kidney injury. Antibiotics do not always eliminate the bacterium completely. Recurring signs may also involve reinfection or an entirely different disease.

Diagnosis at the vet

The vet assesses tick exposure, signs and other health conditions. Diagnosis also excludes other causes of lameness and fever. Anaplasma and other tick-borne pathogens can produce similar signs. Concurrent infection is possible.

Routine blood tests can be normal if changes are confined to the joints. Basic investigations may include a blood count and biochemistry. Low platelets or white blood cells may suggest another tick-borne infection rather than Lyme disease alone. The whole blood count therefore influences further investigation.

A positive antibody result demonstrates exposure. It does not show that this bacterium explains current lameness. Sampling time matters: an ordinary antibody test can be used about 4–8 weeks after a bite. Infection less than 1 month old may still be serologically negative.

Antibodies against the C6 peptide indicate natural exposure. Vaccination does not usually cause a positive C6 result. However, not every antibody test distinguishes vaccination and infection responses in the same way. Test type and previous vaccination are considered during interpretation.

Urinalysis helps look for protein loss suggesting kidney injury. The urine protein-to-creatinine ratio can assess protein loss. A joint fluid sample may show inflammatory cells. Joints may also be X-rayed when needed. Detecting bacterial genetic material in blood is often difficult because Borrelia mainly lives in tissues. PCR can be performed on joint, skin or other affected tissue samples.

Borrelia culture is slow and can take up to 6 weeks. Culture or direct bacterial detection is often negative. The method and sampling site therefore affect what a negative result can establish.

Treatment

The vet prescribes treatment and medicines. Symptomatic Lyme disease is treated with antibiotics. Doxycycline is the most common option. Amoxicillin may be an alternative, for example in a growing dog or when doxycycline is unsuitable. Possible concurrent tick-borne diseases also influence medicine choice.

Vet-prescribed pain relief can treat joint pain. Signs improve in many dogs within 1–2 days of starting treatment. A response range of 1–3 days is also described. Rapid improvement is not an instruction to stop prescribed medication. Persistent signs prompt investigation of another illness and possible reinfection.

A symptom-free antibody-positive dog generally needs monitoring rather than automatic antibiotics. Monitoring may include regular urine tests. Treating a healthy positive dog also carries a risk of medicine adverse effects. Signs and kidney findings are therefore central to treatment decisions.

Severe kidney disease may require hospital care. Treatment may include intravenous fluids. Blood pressure is controlled with medication when needed. Protein loss and nausea can be treated separately. Nutritional support is often necessary too. Medicines suppressing the immune response may be considered for severe progressive immune-mediated disease.

Treatment success is assessed chiefly by improvement in your dog's signs. Antibodies do not necessarily disappear afterwards. A renewed rise in antibody levels may involve recurrent or new infection. Follow-up testing is therefore tailored to signs, kidney health and new tick exposure.

Prevention

Tick control is the most important part of Lyme disease prevention. A suitable product is chosen according to lifestyle and exposure. Coat checks and prompt tick removal supplement protection. Small ticks can be difficult to find in a dense coat.

With fine-tipped tweezers, grasp the tick as close to the skin as possible. Pull slowly straight upwards without twisting. Use a separate tick-removal tool according to its own design. Do not use oil or another substance intended to suffocate the tick. Maintain garden grass and deal with leaf piles.

Vaccination need is assessed from your dog's region, lifestyle and exposure risk. In Europe, benefit depends on which Borrelia species the vaccine is expected to cover. Vaccination does not replace tick medication. Previous infection does not provide reliable natural protection against reinfection.

Vaccination has little therapeutic effect on an infection already established in the body. Vaccine protection is described as lasting about 1 year. An individual vaccination plan is made at the practice according to the product and your dog's risks.

Important for dog owners

Record tick findings, travel and dates of lameness. Take a short walking video if lameness varies between days. Note which leg is tender, how your dog eats and whether drinking or urination has changed. Tell the vet about tick prevention, previous Lyme disease tests and vaccinations. Keep test reports so a previous positive antibody finding can be compared with later signs without assuming new disease.

People do not acquire Lyme disease directly from dogs; infection passes through ticks. However, dogs can bring unattached infected ticks indoors. Check your own skin and clothing after walks too. Attend agreed urine and other checks, and report new general signs promptly.

Frequently asked questions

Does a positive Lyme disease test mean my dog needs antibiotics?

Not automatically. A positive antibody test demonstrates exposure rather than the cause of signs. Symptom-free dogs generally need monitoring. Urine tests can monitor kidney health. The vet assesses medication needs from results, signs and your dog's overall health.

Will a dog get a red ring around a tick bite?

Dogs do not usually develop the expanding ring-shaped rash typical of human Lyme disease. Mild redness may still appear at a bite site. Skin appearance therefore does not determine exposure. A feverish or lame dog needs examination even without visible skin changes.

When should a Lyme disease test be taken?

An ordinary antibody test can be scheduled about 4–8 weeks after a bite to allow antibodies to form. A very recent infection may produce a negative result. However, a dog with signs is not left waiting until then; the vet plans necessary investigations immediately.

How quickly does treatment help lameness?

Many affected dogs respond to antibiotics within 1–2 days. A slightly slower response within 1–3 days is also common. Continue treatment according to the prescribed plan. If signs fail to improve or return, the vet assesses other illnesses and possible reinfection.

Does having Lyme disease protect against reinfection?

Not reliably. Previous Borrelia infection does not provide certain natural immunity. Tick prevention must therefore continue after treatment. Vaccinated dogs also need tick control. Protection is planned according to walks, travel and local tick conditions.