Lyme Disease in Dogs

How Dogs Catch Lyme Disease

Lyme disease is caused by a spiral-shaped bacterium, Borrelia burgdorferi, that lives in certain ticks. Dogs pick it up when an infected black-legged tick, commonly called a deer tick, attaches and feeds on them. The tick generally needs to stay attached for around a day or two before the bacteria pass into the dog, which is exactly why finding and removing ticks quickly is one of the best ways to prevent infection.

These ticks live in wooded, grassy, and brushy areas and are most active in the warmer months, though in mild climates they can be a risk year-round. Dogs that walk, hike, or play in these environments have the highest exposure. Lyme disease is not contagious between animals, so your dog cannot catch it from another dog and cannot pass it to you. The shared danger is the tick itself, which can bite both dogs and people.

Because signs often take two to five months to appear, most owners never see the bite that caused it. A routine tick check after every outing, running your fingers slowly over your dog's skin and paying attention to the ears, neck, armpits, and between the toes, is a simple habit that catches ticks before they can do harm.

Diagnosis and Treatment

Because the symptoms are vague and overlap with many other problems, your vet diagnoses Lyme disease by combining a blood test with your dog's history and physical exam. A common in-clinic screening test checks for antibodies to the bacteria, and further tests can confirm the result and check whether the kidneys are affected. A positive antibody test in a dog with no symptoms does not always mean treatment is needed, so your vet weighs the whole picture.

When treatment is warranted, it is a course of antibiotics, most often doxycycline given for about four weeks. Most dogs improve remarkably quickly, with the lameness and fever easing within a couple of days of starting. Dogs that are sore may also receive pain relief. It is important to finish the full course even after your dog feels better. Antibiotics do not always clear the bacteria completely, so some dogs stay infected and can relapse, and the uncommon kidney form needs much more intensive care.

Sore, swollen joints can make a dog reluctant to move and easy to over-rest, so once your vet gives the go-ahead, gentle activity and keeping your dog at a healthy weight ease the load on the joints. If you are not sure whether your dog is carrying extra pounds, our dog body condition score guide and dog BMI calculator are a good place to start.

Preventing Lyme Disease

The good news is that Lyme disease is largely preventable, and prevention comes down to keeping ticks off your dog and removing any that attach before they can transmit the infection.

• Use year-round tick prevention. A vet-recommended tick preventive, whether a chew, spot-on, or collar, is the foundation. Dose it correctly for your dog's weight and keep it up all year, since ticks can be active whenever it is mild.
• Check for ticks after every outing. Run your hands slowly over your dog after walks in grassy or wooded areas, checking the ears, neck, armpits, groin, and between the toes where ticks like to hide.
• Remove ticks promptly and properly. Use a tick-removal tool or fine-tipped tweezers to grasp the tick as close to the skin as possible and pull straight out, then clean the area. The faster a tick comes off, the lower the risk.
• Manage the environment. Keep grass short, clear leaf litter and brush, and avoid letting your dog push through tall grass in tick season to reduce exposure.
• Ask about the Lyme vaccine. In high-risk regions your vet may recommend a Lyme vaccine as an extra layer of protection alongside tick control.

Ticks are not the only parasite worth guarding against, and a good prevention routine covers several at once. For more on protecting your dog, see our guides to fleas on dogs and heartworm in dogs, or browse the full dog health hub.