Lyme disease is a tick-borne bacterial infection caused by Borrelia burgdorferi, transmitted by infected Ixodes (deer) ticks that have been attached for at least 24–48 hours. In dogs, it most commonly causes joint pain, limping, fever, and lethargy. Unlike in humans, the classic bullseye rash is rarely seen in dogs. Cats are relatively resistant.
Lyme disease is prevalent in northeastern USA, upper Midwest, Pacific coast, and parts of Europe where Ixodes tick species are established. Not all ticks carry the disease — the prevalence of infected ticks varies significantly by region. In endemic areas, screening dogs annually for Lyme antibodies as part of routine heartworm testing (4Dx test) is standard practice.
The most common presentation in dogs is a shifting-leg lameness — limping that moves from leg to leg over days, often accompanied by fever, loss of appetite, and swollen lymph nodes. A severe but less common complication is Lyme nephritis, where the kidneys are affected by immune complex deposition triggered by the infection, which can be fatal. Labrador Retrievers and Golden Retrievers appear to be at higher risk of the renal form.
Treatment with doxycycline for 4 weeks typically resolves clinical signs effectively in most dogs, though antibody levels can remain elevated for months after successful treatment. A Lyme vaccine is available for dogs in endemic areas and is recommended alongside rigorous tick prevention. Daily tick checks and prompt removal within 24–48 hours of attachment remain the most effective prevention strategy.
📌 Key Facts
Causative agent: Borrelia burgdorferi
Tick attachment time needed: At least 24–48 hours
High-risk regions: Northeast USA, upper Midwest, Pacific coast, parts of Europe
Treatment: Doxycycline for 4 weeks | Vaccine available: Yes
Frequently Asked Questions about Lyme Disease
Q: If I find a tick on my dog, does that mean they have Lyme disease?
Not necessarily. Transmission requires the tick to be attached for 24–48 hours. If you removed the tick promptly, the risk is low. Your vet may recommend monitoring for symptoms (lameness, fever, lethargy) over the following weeks and can perform a Lyme test if concerned.
Q: Can humans catch Lyme disease from their dog?
Not directly — Lyme disease is not transmitted from dog to human. However, infected ticks on your dog can transfer to you during petting or grooming. A dog that brings ticks into the home increases your tick exposure risk, which is another reason rigorous tick prevention on pets matters for the whole household.
Q: My dog tested positive for Lyme antibodies but seems healthy — what does this mean?
A positive Lyme antibody test means exposure to the bacteria, not necessarily active disease. Many dogs are exposed and mount an immune response without developing clinical illness. Your vet will assess whether treatment is appropriate based on symptoms, kidney values, and urine protein levels.
⚠ Medical Disclaimer: This glossary entry is for educational purposes only
and does not constitute veterinary advice. Always consult a licensed veterinarian for diagnosis
and treatment of your pet's health conditions.