Lyme Disease in Dogs: Signs, Treatment and Tick Prevention

What it is

Lyme disease is caused by a bacterium called Borrelia burgdorferi, which dogs pick up when an infected blacklegged tick (often called a deer tick) bites and feeds. In North America, the eastern and western blacklegged ticks are the ones shown to pass it to dogs. Ticks wait on grass, leaves, and shrubs for something to latch onto, and they are most active from spring through fall.

The bacteria need time to move from tick to dog. CAPC and the AVMA say a tick usually feeds for about 24 to 48 hours before it can pass them on, while VCA gives a shorter 12 to 24 hours, so daily checks and quick removal matter. Lyme disease does not spread directly from a dog to a person or to another dog; people get it from ticks too.

Many infected dogs never become ill. When they do, signs often show up two to five months after the bite: fever, low energy, poor appetite, swollen lymph nodes, and painful, swollen joints with lameness that shifts from leg to leg. A smaller number develop Lyme nephritis, a protein-losing kidney disease that can cause vomiting, diarrhea, weight loss, swelling, and kidney failure, and is often fatal.

Causes and risk factors

What you can do at home

If you find an attached tick, remove it promptly. Wear gloves if you can, grip the tick close to the skin with fine-tipped tweezers or a tick-removal tool, and pull straight out with steady pressure, without twisting or jerking. Avoid crushing the body with bare fingers, since the contents can carry the bacteria. Wash your hands afterward. Antibiotics are not recommended just because a tick bit your dog, so the next step is watching.

Over the following weeks and months, watch for limping, especially if it moves from leg to leg, plus fever, tiredness, a drop in appetite, or swollen joints. Note the date you found the tick, which helps your vet.

Never give human pain medicines such as ibuprofen, naproxen, or acetaminophen on your own. The FDA warns they can cause stomach ulcers, kidney damage, and liver damage in dogs, and Lyme disease can already involve the kidneys. Use only a pain medicine your vet prescribes for your dog.

Keep fresh water available, let a sore dog rest, and skip hard play until your vet has checked the joints.

What happens at the vet

Your vet will ask about tick exposure, travel, and when signs began, then examine the joints, lymph nodes, and temperature. No single test proves that Lyme disease is the cause of illness. Vets combine the history and signs with a blood test for antibodies to the bacteria. A positive result shows exposure, and many healthy dogs in tick country test positive, so it has to be read alongside the signs. A negative result does not always rule infection out.

Blood and urine tests check the kidneys, including whether protein is leaking into the urine, and your vet may test for other tick-borne infections that cause similar signs. Joint fluid analysis or a PCR test is sometimes added.

Dogs that are ill are usually treated with a course of antibiotics lasting about a month, sometimes longer, and relapse or reinfection can happen. Pain relief may be added for sore joints. Dogs with kidney involvement need extra treatment, which may include intravenous fluids and blood pressure medicine. Healthy dogs that test positive but have no signs are generally not given antibiotics; the plan is closer monitoring and better tick control.

Prevention

Tick control is the foundation. Ask your vet about a year-round tick preventive that is labeled for blacklegged ticks. Options include oral and topical products, and your vet can match one to your dog. Preventives reduce risk but do not make a dog tick-proof, so keep checking.

Run your hands over your dog's whole body after time in grass, brush, or woods, and check again at the end of the day. Stick to cleared trails and keep out of tall grass and marshy or wooded areas when you can. Mowing the grass, trimming shrubs, and clearing brush make your yard less welcoming to ticks.

A Lyme vaccine exists. Vets generally consider it for dogs that live in or travel to areas where Lyme disease is common, usually as an initial series followed by yearly boosters. It does not replace tick control. Ask your vet whether it makes sense for your dog's area and lifestyle. Fleas are a different parasite but also call for year-round control; see fleas in dogs.