The Complete Guide to Tick-Borne Lyme Disease in Dogs

ImmunityDiseasesMeongsiljang Veterinary Advisory Board

Lyme disease in dogs is a bacterial infection transmitted by tick bites. Key signs include arthritis, fever, and loss of appetite. Early antibiotic treatment and tick prevention are essential.

What Is Lyme Disease in Dogs?

An illustration showing a beagle on the grass and a magnified view of a tick nestled in its fur.

Lyme disease in dogs is an infectious condition caused by the bacterium Borrelia burgdorferi, which enters the body through the bite of an Ixodes tick. The most critical factor is early detection. Since the tick must remain attached to the skin and feed for approximately 50 hours (about two days) before transmitting the bacteria, you can prevent a significant number of cases by thoroughly checking your dog for ticks after every walk. If you notice symptoms such as arthritis, fever, lethargy, or loss of appetite, please visit the vet immediately.

Cause: Bacteria Transmitted by Ixodes Ticks

The true cause of Lyme disease is a spiral-shaped bacterium called Borrelia burgdorferi. This bacterium enters your dog's body when ticks from the Ixodes genus, such as the deer tick, feed on blood. Exposure typically occurs from spring through autumn in mountainous areas, wooded regions, and grassy lawns. Infection only takes hold if the tick remains attached to the skin and feeds for approximately 50 hours or more. Therefore, promptly removing ticks right after walks significantly reduces the risk of developing the disease.

Key Symptoms Checklist

Lyme disease is often missed because symptoms typically don’t appear until 2–5 months after infection. If you notice a combination of the following signs, Lyme disease should be considered.

Migratory arthritis: The location of limping shifts, such as affecting the front legs one day and the hind legs the next.

Fever: High fever, higher than normal, persists for several days.

Joint swelling and pain: Joints become swollen and painful to the touch.

Decreased appetite: Refusal to eat usual favorite foods or treats.

Lymph node swelling: Lymph nodes under the jaw or in the armpits feel swollen when touched.

Lethargy: Reluctance to go for walks or move around.

An illustration of a lethargic dog lying down

When to Visit the Vet Immediately

If you notice protein in the urine (proteinuria), swelling in the face or legs, a sudden loss of appetite, or repeated vomiting, Lyme nephropathy (kidney damage) should be suspected. When Lyme nephropathy is present, the prognosis can worsen, and delaying treatment may become life-threatening. Additionally, immediate veterinary care is necessary if there is severe limping that prevents the pet from putting weight on a leg, joint swelling lasting more than 24 hours, or persistent high fever and lethargy.

Diagnostic Methods

Lyme disease is difficult to confirm based on symptoms alone, so blood tests are essential. According to veterinary internal medicine textbooks, infection is quickly confirmed using an antibody test (C6 ELISA SNAP test), and if the result is positive, a quantitative test is performed to measure antibody levels. In cases of severe joint pain, joint fluid may be aspirated to examine inflammatory cells. Urinalysis to check for proteinuria (UPC ratio) is also commonly conducted.

Comparison of Tick Preventives

Item	Spot-on (fipronil)	Chewable (fluralaner)	Collar type (deltamethrin)
Administration method	Applied to the back of the neck	Oral (treat form)	Worn
Duration	About 4 weeks	About 12 weeks	About 6–8 months
Swimming/bathing	Possible after 48 hours	No effect	No effect
Tick prevention	True	True	True

Ingredients and dosages differ by product, so always consult your veterinarian before choosing.

Treatment: Antibiotics and Adjunctive Therapy

The cornerstone of Lyme disease treatment is antibiotic therapy. According to veterinary internal medicine textbooks and ACVIM consensus guidelines, doxycycline is the first-line drug of choice, although minocycline is also an option. While the optimal dosage and duration have not been strictly defined, a treatment course of approximately four weeks is commonly prescribed to account for potential co-infections. If joint pain is severe, nonsteroidal anti-inflammatory drugs (NSAIDs) are often used in conjunction with antibiotics. For Lyme nephropathy, which involves worsening kidney function, aggressive treatment combining doxycycline with immunosuppressants is crucial for survival, alongside hospitalization and dietary management. Your veterinarian will determine the specific dosage and duration based on your pet’s weight and symptoms.

An illustration of a veterinarian examining a dog in the clinic.

Home Care and Prevention Tips

During treatment or recovery, avoid strenuous exercise and stick to short walks on flat, even surfaces. Daily prevention is also important.

Post-walk check: Carefully inspect the inside of the ears, armpits, groin, and between the toes.

Tick removal: Grasp the tick’s head firmly with tweezers and pull it out slowly and steadily; do not crush it.

Avoid tall grass: Stay away from areas with long grass whenever possible.

Year-round preventive medication: Ticks remain active on warm winter days, so using preventive medication year-round is the safest approach.

Caution Regarding Relapse and Chronicity

Even after antibiotic treatment, some Lyme disease bacteria may remain in the body and cause a relapse months later with symptoms such as arthritis or kidney issues. Stopping preventive measures once treatment is complete can lead to reinfection from the same ticks. For at least six months after treatment, it’s important to monitor your pet’s condition through regular blood and urine tests, and using tick preventatives consistently for life is the safest approach.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can Lyme disease be transmitted from dogs to humans?

Ticks themselves don’t transmit directly from dogs to humans. However, since ticks in the same environment can bite people, if your dog has been bitten by ticks, please check your body after walks as well.

Does a tick bite always mean your pet has Lyme disease?

Not at all. Ticks need to be attached to the skin for about 50 hours or more to transmit bacteria. If you remove them quickly after a walk, the risk of infection is significantly reduced.

Is the Lyme disease vaccine absolutely necessary?

Although Lyme disease is relatively uncommon in Korea, it’s a good idea to discuss vaccination with your veterinarian if you frequently go camping or hiking, or if you live in an area with frequent tick exposure.

Is it safe to remove ticks by hand?

Absolutely not. Crushing the tick or leaving its head embedded in the skin significantly increases the risk of inflammation and infection. For safe removal, use tick-removal tweezers or a dedicated tool to gently extract it, or have it removed at a veterinary clinic.

How long should we monitor the pet’s progress after treatment?

We recommend regular blood and urine tests for at least six months. It is essential to confirm that the quantitative C6 antibody levels have decreased sufficiently (by about half or more) compared to pre-treatment levels, and that kidney function markers and proteinuria are within normal ranges, so that relapse or progression to a chronic condition is not missed.

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References

[1] Ettinger, S.J. et al., Textbook of Veterinary Internal Medicine, 8th Edition, Chapter on Tick-borne Diseases

[2] BSAVA Manual of Canine and Feline Dermatology, 4th Edition, Ectoparasite Control Chapter

[3] Littman, M.P. et al., ACVIM consensus update on Lyme borreliosis in dogs and cats, Journal of Veterinary Internal Medicine, 2018

[4] Principles and Practices of Canine and Feline Clinical Parasitic Diseases, Tick-borne Pathogens Section