What Is Lyme Disease in Dogs?
Lyme disease is a bacterial infection caused by Borrelia burgdorferi, transmitted to dogs through the bite of infected blacklegged ticks of the species Ixodes scapularis (in the eastern US) and Ixodes pacificus (on the West Coast). It is one of the most common tick-borne diseases in North America, Europe, and parts of Asia.
Unlike in humans — where the distinctive “bull’s-eye” rash is a reliable early indicator — dogs rarely display this hallmark sign. The majority of dogs exposed to Borrelia burgdorferi never develop clinical illness. However, in the 5–10% that do become symptomatic, the disease can range from mild lameness to severe, life-threatening kidney disease.
How Dogs Get Lyme Disease
Lyme disease is exclusively tick-borne — it cannot be passed directly from dog to dog or from dog to human. Transmission requires a tick to remain attached for at least 24–48 hours, so prompt tick removal is highly protective. The disease is most common in the northeastern United States, the upper Midwest, and much of Europe. Dogs at highest risk are those who spend time in wooded areas, tall grass, leaf litter, and dense brush. Outdoor dogs, hiking companions, and dogs in rural or suburban areas near woodland are most vulnerable. Ticks are active year-round in mild climates but peak in spring and autumn.
Signs and Symptoms of Lyme Disease in Dogs
Symptoms typically appear 2–5 months after a tick bite, which is why owners often do not connect the illness to a specific tick exposure. Shifting-leg lameness — intermittent lameness that moves from one leg to another — is the most characteristic sign, with affected joints often swollen, warm, and painful to the touch. Lethargy causes infected dogs to seem unusually tired and reluctant to play or exercise. Fever above 39.5°C (103°F) is common during acute illness. Loss of appetite and swollen lymph nodes are also frequently observed.
A serious complication — Lyme nephritis — occurs in a small subset of dogs and causes acute kidney failure, which can present as vomiting, extreme lethargy, swelling of the legs or face, and can be fatal without aggressive treatment.
Diagnosis and Treatment of Lyme Disease in Dogs
Your veterinarian will use a combination of history, clinical signs, and diagnostic tests. A 4Dx or SNAP test detects antibodies against the bacteria — a positive result confirms exposure but not necessarily active disease. The quantitative C6 test measures specific antibody levels to gauge whether disease is active and monitor treatment response. Urinalysis and kidney function panels are performed in all positive dogs to screen for early kidney involvement.
Treatment is with antibiotics — most commonly doxycycline at 5 mg/kg twice daily for 28–30 days. Improvement in lameness and fever is usually seen within 3–5 days of starting treatment. Dogs with kidney disease require additional aggressive therapy including IV fluids and kidney-supportive medications.
Prevention of Lyme Disease in Dogs
Prevention is considerably more effective than treatment. Prescription tick prevention products such as Bravecto, NexGard, or Simparica Trio kill ticks quickly — typically within hours of attachment — before transmission can occur. The Lyme vaccine is highly effective and recommended in high-risk areas; the initial series requires two doses 2–4 weeks apart followed by annual boosters. Daily tick checks after every outdoor excursion are essential — check especially around the ears, between the toes, under the collar, around the tail, and in the groin area. Safe tick removal using fine-tipped tweezers grasping as close to the skin as possible prevents transmission. Landscape management including mowing grass and clearing leaf litter also reduces tick habitat.
Talk to your local HeiBob veterinarian about which prevention strategy is right for your dog based on your location and lifestyle.