Lyme Disease in Dogs: Symptoms, Treatment, Prevention, and Pet Insurance

Lyme disease is one of the most common tick-borne illnesses in the United States, affecting dogs primarily in the northeastern and upper midwestern states — with its geographic reach continuing to expand. Caused by a bacterium transmitted through deer tick bites, it can produce joint pain, fever, and in a small number of cases, serious kidney damage. Understanding the signs, how it’s treated, and how to prevent it can help owners protect their dogs and plan for potential vet costs.

What Is Lyme Disease in Dogs?

Lyme disease is caused by Borrelia burgdorferi, a bacterium carried primarily by the blacklegged tick (commonly called the deer tick). The disease is most common in the northeastern United States and the upper Midwest, though the Companion Animal Parasite Council projects ongoing geographic expansion as blacklegged tick populations continue to spread southward and westward.²

A key characteristic of canine Lyme disease is that most exposed dogs do not become ill. According to the AVMA, only 5–10% of dogs infected with Borrelia burgdorferi develop clinical signs of disease.¹ This means that a positive Lyme antibody test result indicates prior exposure — not necessarily active illness — which plays an important role in how veterinarians approach treatment decisions.

Symptoms of Lyme Disease in Dogs

The most recognizable sign of Lyme disease in dogs is sudden lameness — a limp that may shift between legs over days or weeks as different joints become inflamed.¹ Because symptoms typically appear two to five months after infection, owners may not initially connect them to a tick bite. Other signs can include:

A more serious complication is Lyme nephritis, a form of kidney disease caused by immune responses to the infection. The AVMA notes that 1–5% of infected dogs develop kidney involvement.¹ Signs usually include vomiting, increased thirst and urination, weight loss, and severe lethargy. Lyme nephritis carries a poor prognosis and requires intensive veterinary management, including hospitalization in acute cases.

Diagnosis and Treatment

Transmission of Lyme disease requires a tick to remain attached for at least 24–48 hours¹, which is why daily tick checks — especially after outdoor activity in wooded or grassy areas — can meaningfully reduce infection risk. Prompt, proper tick removal is one of the most practical preventive steps available.

Diagnosis typically involves a blood antibody test, often included as part of routine annual heartworm/tick-borne disease testing. A positive result confirms prior exposure to Borrelia burgdorferi. Veterinarians will evaluate the dog’s clinical signs, bloodwork, and history to determine whether active infection and treatment are warranted.

For dogs with clinical signs of Lyme disease, the standard treatment is a 4-week course of doxycycline. Most dogs show improvement within one to two days of starting antibiotics.¹ Dogs with kidney involvement require additional diagnostics, a more intensive antibiotic protocol, and supportive care. Urgent or emergency vet care may be needed for dogs presenting with signs of acute kidney failure.

Preventing Lyme Disease in Dogs

Prevention of Lyme disease in dogs relies on two complementary strategies: consistent tick control and vaccination.¹

Tick prevention products are the foundation of any prevention plan. Monthly oral chewables (such as those containing afoxolaner or fluralaner) and topical treatments kill or repel ticks before they can transmit the bacteria. Tick collars provide an additional layer of protection. Using these products year-round is recommended in endemic regions, since ticks remain active at temperatures above freezing.

The Lyme vaccine is a good tool for dogs in high-risk areas. The initial series requires two doses, followed by annual boosters. While it does not guarantee complete protection, it reduces both the likelihood of infection and the severity of illness in dogs that are exposed. Staying current on your dog’s vaccinations — including disease-specific vaccines recommended based on lifestyle and region — is a core part of routine preventive care. Your veterinarian can assess your dog’s individual risk and recommend a prevention protocol suited to where you live and how much time your dog spends outdoors.

Does Pet Insurance Cover Lyme Disease?

Accident and illness plans can help cover eligible costs associated with Lyme disease diagnosis and treatment — including blood testing, antibiotics, and care for complications such as joint inflammation or kidney disease. What pet insurance covers varies by plan, but tick-borne illnesses may be covered conditions under some extensive accident and illness policies.

Enrollment timing matters significantly. Pet insurance typically does not cover pre-existing conditions. A dog that has already been diagnosed with Lyme disease — or had a positive Lyme antibody test documented before a policy takes effect including during any waiting period — may have the condition excluded from coverage. Enrolling before a dog’s first tick season, or before any tick-borne illness is documented, offers the broadest coverage eligibility.

Some policies also offer optional preventive care add-ons that can help offset the eligible cost of the Lyme vaccine and annual boosters. Finding the right time to enroll is important to help avoid pre-existing condition exclusions.

The right pet insurance plan should help support your pet through both unexpected accidents and health needs. Understanding what’s included in your policy can help you choose coverage that fits your pet’s lifestyle.

Spot Pet Insurance offers accident and illness coverage to help reimburse eligible costs related to covered injuries, illnesses, diagnostics, and treatment. Pet parents can also add optional preventive care coverage for routine services like annual exams, dental cleanings, and certain vaccines. Learn more about what pet insurance covers.