Lyme Disease in Dogs: Signs, Testing and Treatment

Written by Corinne Homer, Copywriter. Reviewed by Dr. Linda Simon MVB MRCVS, Team Vet.

Canine Lyme disease is caused by infection with Borrelia burgdorferi bacteria transmitted by infected blacklegged ticks. Many exposed dogs never become clinically ill, so a tick bite or positive antibody test does not automatically mean the dog has Lyme disease. Compatible signs, exposure history and veterinary testing must be interpreted together.

US risk is highest in the Northeast, mid-Atlantic and upper Midwest, with some Pacific Coast exposure and changing local patterns. Dogs can encounter ticks in yards and neighborhoods as well as woods. Year-round prevention, daily checks after outdoor activity and a vaccination discussion based on individual risk provide the strongest practical defense.

What is Lyme disease?

Lyme borreliosis is a tickborne bacterial infection. A blacklegged tick acquires the organism from infected wildlife and may later transmit it while feeding. Dogs do not spread Lyme disease directly to people. However, a pet can carry unattached ticks into the home, so prevention protects the household as well as the dog.

Not every tick is infected, and infection does not equal illness. Clinical disease in dogs most often involves fever, reduced appetite and musculoskeletal pain or lameness. A rare but serious kidney complication can develop in some dogs.

How common is Lyme disease in dogs?

Risk varies by county, travel history, habitat, season and use of effective tick control. Testing data change over time as ticks expand into new areas. Ask a veterinarian about local prevalence rather than relying on a national average or assuming an urban yard is tick-free.

Most dogs with antibodies against the organism have no evidence of clinical disease. This is why routine screening results need context and why treating every positive dog with antibiotics is not automatically recommended.

Symptoms of Lyme disease in dogs

Signs may appear weeks or months after exposure and can overlap with many other diseases:

• Fever
• Reduced appetite
• Lethargy or lower activity
• Stiffness or joint pain
• Limping that may shift from one leg to another
• Swollen lymph nodes
• Reluctance to move

These signs are not specific. Injury, immune-mediated joint disease, other tickborne infections, orthopedic disease and systemic illness can look similar. A circular “bull's-eye” rash is a recognized human sign but is not a reliable way to identify Lyme disease in a dog.

First signs to notice

A dog may seem quieter, skip a meal, rise stiffly or develop a limp without an obvious injury. Record when the change began, recent travel, known tick attachments and whether the affected leg changes. Do not wait for a previously found bite to become red because the site may be hidden by hair or already healed.

Signs of possible kidney involvement

Lyme-associated nephritis is uncommon but potentially life-threatening. Warning signs can include vomiting, appetite loss, weight loss, marked lethargy, increased thirst or urination, and swelling from fluid retention. These require prompt veterinary assessment. Urine protein measurement and bloodwork help the veterinarian evaluate kidney function.

How veterinarians diagnose canine Lyme disease

Diagnosis starts with history and examination. The veterinarian considers geography, travel, tick prevention, vaccination, timing and compatible signs. Blood antibody tests show exposure or infection, not necessarily active illness. Some tests distinguish antibodies associated with natural exposure from those produced by vaccination.

Because other tickborne organisms can be transmitted in the same environments, testing may include coinfections. A complete blood count, chemistry panel and urinalysis can identify complications or alternate explanations. Joint-fluid testing or imaging may be appropriate for persistent lameness.

What a positive test means

A clinically normal dog with a positive screening result should not be treated from the number alone. CAPC recommends evaluating for other tickborne infections and abnormalities such as protein in the urine, then establishing effective tick control. Decisions about monitoring or treatment belong with the veterinarian.

Are there three stages of Lyme disease in dogs?

Online descriptions sometimes divide disease into three stages borrowed from human medicine or simplified timelines. Veterinary Lyme disease is not reliably managed by assigning every dog to a universal stage 1, 2 or 3. Dogs may be exposed without illness, develop acute musculoskeletal signs or, rarely, serious renal complications.

Use clinical findings and diagnostic results rather than a numbered internet stage. A dog with mild-looking signs can still need testing, while a positive dog without signs may not have clinical disease.

Treatment and prognosis

Doxycycline is commonly used for clinical canine Lyme disease, with the veterinarian selecting the dose and duration. Pain control or additional supportive care may be needed. Many dogs with musculoskeletal signs improve after treatment, but a quick response does not prove that every prior symptom came from Lyme disease.

Kidney involvement carries a guarded prognosis and may require hospitalization, fluid and blood-pressure management, treatment of protein loss and intensive monitoring. Never use leftover antibiotics or stop a course early without veterinary direction.

Can Lyme disease in dogs be cured?

Many clinically affected dogs recover well, especially when disease is recognized before serious complications. The organism can be difficult to eliminate completely, and future tick bites can cause reinfection or transmit a different pathogen. Continued prevention and follow-up remain important after signs resolve.

Caring for a dog during treatment

Give medication exactly as prescribed and report vomiting, diarrhea, appetite loss or difficulty dosing. Keep activity within the veterinarian's recommendation while joints are painful. Provide secure footing, comfortable rest and easy access to water. Do not test recovery with a long hike or intense play.

Track temperature only if the veterinary team shows you how, and record appetite, water intake, urination, movement, energy and every medication. Seek urgent care for collapse, breathing difficulty, repeated vomiting, inability to stand, marked swelling or rapid deterioration.

What should a dog with Lyme disease eat?

Most dogs need a complete and balanced diet that fits life stage and any other medical condition. There is no universal “Lyme diet” and no food cures the infection. If appetite is poor, ask whether a different texture, therapeutic diet or anti-nausea treatment is appropriate. Kidney involvement can change nutritional needs substantially, so do not improvise a high-protein or low-protein diet.

Antibiotics and digestive signs

Antibiotics can change stool or appetite, but diarrhea during treatment is not a reason to stop medication independently. Contact the prescribing clinic. Probiotics and supplements are product- and strain-specific and can interfere with a clean assessment when several changes begin together.

Preventing Lyme disease

Use veterinarian-recommended tick control

Choose a product labeled for dogs and follow its weight, age and dosing directions. Discuss seizure history, bathing, swimming, household cats and local tick species with the veterinarian. Never use a dog tick product on a cat unless a veterinarian specifically confirms it is safe for that cat.

Check the dog after outdoor activity

Run fingers slowly through the coat and inspect around the ears and eyelids, under the collar and front legs, between toes, between the rear legs and around the tail. Check daily when exposure is possible. A fine comb can help with long or dense coats.

Remove an attached tick promptly with fine-tipped forceps or a commercial removal tool. Grasp close to the skin and pull with steady pressure without crushing the body. Wear gloves, wash hands and clean the site. Do not burn, smother or twist the tick. Ask the veterinary team what local identification or testing is useful.

Discuss Lyme vaccination

Vaccination can be appropriate for dogs living in or traveling to endemic or emerging areas. It does not replace tick control because ticks carry other pathogens and vaccines do not prevent ticks entering the home. Risk assessment should consider geography, travel and outdoor lifestyle.

Reduce tick habitat

Keep grass short, remove leaf litter and brush, and create a dry wood-chip or gravel boundary between frequently used lawn and wooded edges where practical. Check gear and people after hikes. Read our dog-proof yard guide for wider outdoor safety.

When to contact a veterinarian

Call after finding an attached tick if you are unsure about removal, local risk or prevention. Book an examination for fever, reduced appetite, stiffness, swollen lymph nodes or unexplained limping. Seek urgent care for signs of kidney disease, collapse, severe pain or rapid decline.

Keep the prevention schedule visible to every caregiver and record the date and location of any attached tick. Include trips to endemic areas even when the dog seemed healthy during travel. This history can become important weeks or months later if fever, stiffness, appetite loss or unexplained lameness develops.

Frequently asked questions

Can people catch Lyme disease from a dog?

Dogs do not directly transmit Lyme disease to people. Pets can carry ticks indoors, so check pets, clothing and people after outdoor exposure.

Should every tick bite be treated with antibiotics?

No. Preventive antibiotics after a bite are not routinely recommended for dogs. Remove the tick, discuss local risk with a veterinarian and monitor as directed.

Can a vaccinated dog still get Lyme disease?

Vaccination reduces risk but does not replace tick control or daily checks. No vaccine protects against every tickborne pathogen.

How long after a bite can signs appear?

Signs may be delayed for weeks or months. Provide the veterinarian with travel and exposure history even when the last hike was not recent.

Can a dog be positive without being sick?

Yes. Many seropositive dogs show no clinical disease, which is why symptoms and additional tests must be interpreted with the antibody result.

Trusted US sources and related guides

Use the CDC's guidance on preventing ticks on pets and the Companion Animal Parasite Council's canine Lyme disease guideline. For related care, see our kidney disease guide, dog diarrhea guide and dog appetite guide.