Quick answer: Lyme disease in dogs is caused by the bacteria Borrelia burgdorferi, spread mainly by blacklegged (deer) ticks. Most infected dogs never show symptoms. When signs appear, usually weeks to months after the bite, they include lameness that shifts between legs, swollen joints, fever, tiredness, swollen lymph nodes and loss of appetite. A simple blood test can detect exposure, and antibiotics like doxycycline usually treat it well. Rarely, Lyme can damage the kidneys. Year-round tick prevention, daily tick checks and, for some dogs, the Lyme vaccine are the best protection.

What is Lyme disease in dogs?

Lyme disease is a bacterial infection caused by Borrelia burgdorferi. It's spread almost entirely through the bite of an infected blacklegged tick, also called the deer tick. On the West Coast, the closely related western blacklegged tick spreads it.

Dogs can't catch Lyme from other dogs or people, and you can't catch it from your dog. But your dog can bring infected ticks into your home and yard, which is one more reason tick prevention matters for the whole family.

Lyme disease is one of several diseases ticks can spread to dogs. Others include anaplasmosis, ehrlichiosis and Rocky Mountain spotted fever, and some dogs are infected with more than one at the same time.

Where is Lyme disease most common?

In the US, Lyme is most common in the Northeast, the mid-Atlantic and the upper Midwest, including states like Connecticut, Massachusetts, New York, Pennsylvania, New Jersey, Wisconsin and Minnesota. It's also found on the Pacific Coast, especially Northern California.

Lyme is spreading. As tick populations move into new areas, more dogs are being exposed in places that once had few cases. The Companion Animal Parasite Council publishes maps showing how many dogs test positive in each county, which is a great way to check your local risk.

If you travel with your dog to the woods, the lake or a family cabin, check the risk there too. A dog who lives in a low-risk area can easily pick up ticks on vacation.

How do dogs get Lyme disease?

Blacklegged ticks live in wooded areas, tall grass, leaf litter and brush. They don't jump or fly. Instead, they climb onto grass and plants and wait for an animal to brush past.

An infected tick usually needs to stay attached for about 24 to 48 hours to pass on the bacteria. That's why daily tick checks and fast-acting tick preventives are so effective: removing or killing ticks quickly can stop transmission.

Young ticks, called nymphs, are about the size of a poppy seed and are very easy to miss. They're most active in late spring and summer. Adult ticks are active in fall and can stay active on warm winter days, even when there's snow on the ground.

When is tick season?

Many people think of ticks as a summer problem, but blacklegged ticks are active for much of the year. In many parts of the US, there's no truly safe month to stop tick prevention.

• Spring (March to May). Adult ticks that survived winter become active, and nymphs begin to emerge. A great time to restart daily checks and make sure prevention is up to date.
• Late spring and summer (May to August). Nymphs are most active. They're tiny and easy to miss, and they cause a large share of Lyme infections.
• Fall (September to November). Adult ticks are very active again, often on hunting trails, in leaf piles and in tall grass.
• Winter (December to February). Adult ticks can still be active whenever temperatures rise above freezing, even with snow around.

This is why most vets recommend year-round prevention in areas where Lyme is common. Skipping a few winter months can leave a gap at exactly the wrong time.

What are the symptoms of Lyme disease in dogs?

Here's the surprising part: most dogs infected with Lyme never show any symptoms at all. Studies suggest only a small percentage of infected dogs become sick. When symptoms do appear, they usually show up two to five months after the tick bite, not right away.

• Lameness that shifts between legs. The classic sign. Your dog may limp on one leg for a few days, then on another.
• Swollen, warm or painful joints. Your dog may be reluctant to walk, jump or climb stairs.
• Fever. Often with tiredness and low energy.
• Loss of appetite. Eating less than usual or skipping meals.
• Swollen lymph nodes. Especially near the site of the tick bite.
• Stiffness and walking hunched. A sign of pain.
• Signs of kidney problems (rare). Vomiting, weight loss, increased thirst and urination, and swelling in the legs or belly.

Unlike people, dogs rarely get the bull's-eye rash. If your dog shows any of these signs, especially after time outdoors, call your vet. Many of these symptoms can also be caused by other conditions, so a vet exam is the best next step.

What is Lyme nephritis?

Lyme nephritis is a rare but serious complication where the immune response to Lyme damages the kidneys. It's uncommon, but it can be life-threatening, so it's worth knowing about.

It seems to be more common in certain breeds, including Labrador Retrievers, Golden Retrievers and Bernese Mountain Dogs. Signs include vomiting, loss of appetite, weight loss, increased drinking and urination and fluid swelling.

This is one reason vets often recommend a urine test for dogs who test positive for Lyme, even if they seem healthy. Catching protein in the urine early gives your vet the chance to treat and monitor before kidney damage becomes severe.

How is Lyme disease tested?

Most vets screen for Lyme with a simple blood test, often done at your dog's annual checkup alongside the heartworm test. A common in-clinic test checks for heartworm and several tick-borne diseases at once, with results in minutes.

• Screening test. Detects antibodies, which shows exposure to Lyme bacteria. It doesn't tell you whether your dog is sick.
• Follow-up quantitative test. Measures antibody levels to help decide whether treatment is needed and to monitor response.
• Urine test. Checks for protein in the urine, an early sign of kidney involvement.
• Blood work. Checks overall health and kidney function.

Annual testing is recommended in many areas, even for dogs on tick prevention, because no product is 100 percent effective. Your vet will recommend a schedule based on your local risk. Our vaccination schedule guide explains how these tests fit into yearly care.

My dog tested positive for Lyme. Now what?

Take a breath. A positive screening test means your dog has been exposed to the bacteria, not necessarily that they're sick. Many positive dogs live completely normal, healthy lives.

Your vet will look at the whole picture: whether your dog has symptoms, a follow-up antibody level and a urine test for protein. Based on those results, they may recommend treatment, monitoring or both.

Dogs with symptoms or protein in their urine are usually treated. For dogs with no symptoms and normal urine, vets differ on whether to treat, and some prefer to monitor. Ask your vet to walk you through their reasoning, and plan for regular urine checks in the months ahead.

A positive test is also a signal that ticks are reaching your dog. It's a great moment to review your tick prevention plan.

How is Lyme disease treated?

Lyme disease in dogs is usually treated with antibiotics, most often doxycycline, for about four weeks. Many dogs with joint pain start feeling better within a few days.

Your vet may also prescribe pain relief for sore joints. Never give your dog human pain medicines like ibuprofen or acetaminophen, which can be toxic.

Dogs with kidney involvement need more intensive care, which may include special diets, medications to protect the kidneys and regular monitoring. Even after successful treatment, some dogs stay antibody positive for a long time, and dogs can be reinfected by future tick bites.

How can I prevent Lyme disease in my dog?

Prevention is far easier than treatment. The best approach combines several layers of protection.

• Year-round tick prevention. Use a vet-recommended tick product, such as an oral chewable, topical treatment or tick collar. Many work by killing ticks quickly, before they can transmit disease. Never use dog products on cats.
• Daily tick checks. Check your dog every day during tick season, and after every walk in woods or tall grass. Run your fingers through the coat, feeling for small bumps.
• Check the hot spots. Ears, around the eyes, under the collar, armpits, between toes, groin and under the tail.
• Keep your yard tick-unfriendly. Mow grass short, clear leaf litter and brush, and create a gravel or wood chip barrier between lawn and woods.
• Stick to the center of trails. Avoid brushing against tall grass and shrubs.
• Ask about the Lyme vaccine. Recommended for many dogs in high-risk areas.

For a full guide to choosing products and removing ticks, read flea and tick prevention for dogs.

Comparing tick prevention options

There are several types of tick prevention, and the best choice depends on your dog's health, lifestyle and your vet's advice.

• Oral chewables. Given monthly or every few months. Many kill ticks quickly after they bite and aren't affected by swimming or bathing. Some require a prescription.
• Topical spot-ons. Applied to the skin between the shoulder blades. Some repel ticks as well as killing them. Bathing and swimming can affect how well some work.
• Tick collars. Release active ingredients over several months. Make sure the collar fits well and is approved for your dog's size.
• Sprays and shampoos. Offer short-term protection and are usually used alongside longer-lasting products.

Ask your vet which product fits your dog, and always follow the label for weight and dosing. Some dog products, especially those containing permethrin, are toxic to cats, so take care in multi-pet homes. Mark the date on your calendar so doses never slip.

Your after-walk tick routine

Make tick checks part of coming home, just like wiping muddy paws. A quick two-minute check after every outdoor walk catches most ticks before they can transmit disease.

Start at the head and work back. Run your fingers slowly through your dog's coat, feeling for small bumps. Check inside and behind the ears, around the eyes and muzzle, under the collar, in the armpits, between the toes and paw pads, around the tail and in the groin. Use a flea comb for thick coats.

Light-colored bandanas and coats make it easier to spot ticks crawling on your dog before they attach. Brush your dog outside if possible, and check your own clothes and skin too. Our spring hiking guide includes a full packing list with tick tools.

Should my dog get the Lyme vaccine?

The Lyme vaccine is a non-core vaccine, which means it's recommended based on your dog's lifestyle and where you live, rather than for every dog. The AAHA vaccination guidelines consider it for dogs living in or traveling to areas where Lyme is common.

The vaccine is not a replacement for tick prevention. It's an extra layer. Dogs usually receive two initial doses a few weeks apart, followed by yearly boosters.

Talk to your vet about whether the vaccine is right for your dog. They'll consider your region, how much time your dog spends outdoors and your dog's health history.

How do I remove a tick from my dog?

If you find a tick, remove it as soon as possible. Here's how:

• Use fine-tipped tweezers or a tick tool. Grip the tick as close to the skin as you can.
• Pull straight up with steady pressure. Don't twist or jerk, which can leave mouthparts behind.
• Clean the area. Wash with soap and water or a pet-safe antiseptic.
• Save the tick. Put it in a sealed bag or jar with rubbing alcohol in case your vet wants to identify it.
• Don't use folk remedies. Matches, petroleum jelly and nail polish don't work and can make things worse.
• Watch the spot. A small bump for a few days is normal. Call your vet if it gets red, swollen or infected.

If you're not comfortable removing a tick yourself, or the tick is near your dog's eye, call your vet. They can remove it safely and check the area. Keep a tick tool in your first aid kit and car so you're ready on every adventure.

Other tick-borne diseases to know

Lyme gets the headlines, but ticks can spread several other diseases to dogs. Many vets test for them at the same time.

• Anaplasmosis. Spread by the same blacklegged ticks. Signs include fever, joint pain, lethargy and sometimes bleeding problems.
• Ehrlichiosis. Spread mainly by brown dog ticks and lone star ticks. Can cause fever, weight loss, bleeding and low platelet counts.
• Rocky Mountain spotted fever. Spread by American dog ticks and others. Can cause fever, joint pain and vomiting, and can become serious quickly.
• Babesiosis. A parasite that attacks red blood cells. Can cause weakness, pale gums and dark urine.

The same prevention steps protect against all of them. If your dog shows unusual signs after time outdoors, mention any tick exposure to your vet.

Can people get Lyme disease from dogs?

No. Lyme doesn't spread directly from dogs to people. But dogs can carry unattached ticks into your home, which can then bite family members. A dog who tests positive is a useful warning that ticks carrying Lyme are active in your area, so it's a good time to check yourself and your family after outdoor activities too.

The CDC has helpful information about protecting people from tick bites, including using repellents and checking for ticks after time outside.

Questions to ask your vet about Lyme

Bring these to your next checkup, especially before spring:

• How common is Lyme where we live and travel?. Your vet sees local cases and knows the risk.
• Which tick prevention do you recommend for my dog?. And how often should I give it?
• Should my dog get the Lyme vaccine?. Based on lifestyle, region and health.
• How often should we test?. Many vets test yearly with the heartworm test.
• If my dog tests positive, what are the next steps?. Ask about urine tests and follow-up plans.
• Is my breed at higher risk for kidney complications?. Especially for Labs, Goldens and Bernese Mountain Dogs.

Write down the answers, set reminders for prevention doses and add your next test date to your calendar. A clear plan takes the worry out of tick season.

Lyme disease myths

A few misunderstandings come up again and again:

• Every tick bite means Lyme. Most tick bites don't transmit Lyme, especially if ticks are removed quickly.
• A positive test means my dog is sick. It means exposure. Your vet will decide if treatment is needed.
• Ticks die in winter. Adult blacklegged ticks can be active on warm winter days.
• Indoor dogs don't need prevention. Ticks can hitch rides on people and other pets.
• The vaccine means I can skip tick prevention. Both work best together.

Cheat sheet

Your tick season game plan:

• Use tick prevention year-round.
• Check your dog daily, especially after walks.
• Remove ticks quickly with tweezers or a tick tool.
• Watch for shifting lameness, fever and low energy.
• Test yearly as your vet recommends.
• Ask about the Lyme vaccine in high-risk areas.

• Most exposed dogs never get sick. But testing and monitoring still matter.
• Shifting lameness is the classic sign. Often months after the bite.
• Treatment usually works well. Typically about four weeks of antibiotics.
• Prevention is layered. Tick products, daily checks and the vaccine.
• Ask about kidney checks. Especially for Labs, Goldens and Berners.

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Can dogs get Lyme disease?

Yes. Dogs get Lyme from the bite of an infected blacklegged tick.

What are the first signs of Lyme disease in dogs?

Lameness that shifts between legs, swollen joints, fever, tiredness and loss of appetite.

How soon do Lyme symptoms appear in dogs?

Usually two to five months after the tick bite, if they appear at all.

Is Lyme disease curable in dogs?

Most dogs respond well to antibiotics, though some stay antibody positive and can be reinfected.

How long does a tick need to be attached to transmit Lyme?

Usually about 24 to 48 hours.

Does a positive Lyme test mean my dog is sick?

Not always. It means exposure. Your vet will check for symptoms and kidney involvement.

Is the Lyme vaccine safe for dogs?

It's widely used and generally well tolerated. Ask your vet if it's right for your dog.

Can my dog give me Lyme disease?

No, but dogs can carry ticks into your home.

What is the best tick prevention for dogs?

Ask your vet. Many vets recommend fast-acting oral or topical products used year-round.

Do dogs get a bull's-eye rash with Lyme?

Rarely. Dogs usually show lameness or fever instead.