Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Lyme disease is caused by Borrelia burgdorferi bacteria, spread by blacklegged (deer) ticks. Most dogs that are exposed never get sick. When they do, signs usually include shifting leg lameness, swollen joints, fever, and lethargy, often weeks to months after the tick bite. It’s treated with antibiotics, typically doxycycline for about 4 weeks. A rare but serious form, Lyme nephritis, damages the kidneys, so vets check the urine for protein in dogs that test positive.
Signs
- Lameness that may shift from leg to leg
- Swollen, warm, or painful joints
- Fever
- Lethargy and poor appetite
- Enlarged lymph nodes
Lyme nephritis (kidney form)
A small number of dogs, particularly Labrador and Golden Retrievers, develop kidney damage linked to Lyme disease. Signs include vomiting, poor appetite, weight loss, increased thirst and urination, and swelling. This form is serious and needs prompt treatment.
Testing
- Screening tests detect antibodies, which show exposure, not necessarily illness.
- A positive test in a healthy dog is common in areas with Lyme disease.
- Urine protein testing (urinalysis and urine protein:creatinine ratio) is recommended for dogs that test positive, to screen for kidney involvement.
- Tests for other tick-borne diseases, such as Anaplasma and Ehrlichia, which often occur alongside Lyme.
Treatment
- Doxycycline for about 4 weeks is the usual treatment for sick dogs. Many improve within a few days.
- Pain relief for joint pain, as your vet prescribes.
- Kidney treatment for Lyme nephritis, including medication to reduce protein loss and sometimes immune-suppressing drugs.
- Healthy dogs that test positive: the ACVIM consensus generally doesn’t recommend treatment unless there are signs of illness or protein in the urine. Your vet will discuss this.
Is there “chronic Lyme” in dogs?
The bacteria can persist in some dogs even after treatment, and signs can return. However, many ongoing problems in dogs that tested positive turn out to have another cause, such as arthritis or a different tick-borne infection. If signs continue after treatment, your vet will look for other explanations.
Prevention
- Year-round tick prevention with a veterinary product.
- Daily tick checks after outdoor time, especially around ears, toes, and under the collar.
- Remove ticks promptly with fine-tipped tweezers, pulling steadily from close to the skin.
- Lyme vaccine for dogs in high-risk areas, as your vet recommends.
- Keep grass short and avoid tick-heavy brush.
What to avoid
- Burning or smothering ticks with petroleum jelly or nail polish.
- Human antibiotics or leftovers.
- Essential oil “tick repellents,” which are unreliable and can be toxic, especially around cats.
- Human pain relievers.
Frequently asked questions
Can people catch Lyme disease from dogs?
Not directly. But dogs can bring ticks into the home, and both dogs and people can be bitten by infected ticks.
How long after a tick bite do signs appear?
Usually 2–5 months.
Should I treat my dog if it tested positive but seems fine?
Talk to your vet. Urine protein testing helps decide.
Sources
- Littman MP, et al. ACVIM consensus update on Lyme borreliosis in dogs and cats. J Vet Intern Med. 2018
- Companion Animal Parasite Council (CAPC): Lyme disease guidelines
- Merck Veterinary Manual: Lyme borreliosis in animals
- US Centers for Disease Control and Prevention (CDC): Tick removal
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.