Overview of Lyme Disease in Dogs
Lyme disease, caused by the bacterium Borrelia burgdorferi, is one of the most common tick-borne illnesses found in dogs, especially in the Northeastern U.S. It's transmitted by black-legged ticks (also known as deer ticks), particularly in their nymph and adult stages. In places like New England, it's not unusual for 50–75% of dogs tested to return a positive result.
Despite this, Lyme disease remains controversial in veterinary medicine—primarily because many dogs that test positive don’t show any signs of illness.
My Dog Tested Positive—Does That Mean He’s Sick?
A positive test doesn’t always require immediate treatment. Most dogs exposed to the Lyme organism remain healthy and show no symptoms. Only about 1 in 10 will go on to develop clinical illness.
That said, if your dog does test positive, a follow-up blood test can help determine whether the infection is current or past. This distinction is important because treatment is generally only recommended for dogs showing signs of active infection, such as lameness, swollen joints, lethargy, fever, or enlarged lymph nodes. These signs typically appear 2–5 months after exposure and usually respond well to antibiotics like doxycycline.
Annual Lyme screening may be advisable in high-risk areas like Massachusetts.
Are Bigger Ticks Safer? Not Necessarily.
It’s a myth that only tiny ticks can spread Lyme. Engorged adult ticks might look large, but they can still be black-legged ticks capable of carrying Lyme disease. A lab test may be needed to confirm the tick species if there's any doubt.
What If I Find a Tick on My Dog?
You can remove it yourself if you're comfortable. Use clean tweezers to grasp the tick near your dog’s skin and pull straight out without twisting. After removal, clean the area and wash your hands. A vet visit isn't always needed unless the tick’s been on for an extended time, or if your dog starts showing symptoms.
How Long Does It Take to Get Infected?
A tick must typically be attached for at least 48 hours to transmit the Lyme bacterium. That’s why routine tick checks are one of the best defenses. Check your dog daily, especially after outdoor adventures.
Preventing Tick Bites
To reduce the risk of Lyme disease, use veterinarian-recommended tick preventives like Frontline or Advantix (for dogs only). Avoid bathing or letting your dog swim for 24 hours after applying these products so they remain effective. There are also oral preventives—your vet can help you choose the best option.
Are Ticks Gone After the First Frost?
Unfortunately, no. Ticks don’t die off completely in cold weather. Adult black-legged ticks can remain active during any mild stretch in winter. Even when there’s snow, warmer days can bring them back out.
Can My Dog Give Me Lyme Disease?
Not directly. Dogs can’t pass Lyme disease to humans. However, if a tick detaches from your pet and bites you, transmission is possible. Keeping your dog tick-free helps protect the whole household.
Should I Vaccinate My Dog for Lyme Disease?
There are vaccines available to help prevent Lyme disease in dogs. Whether or not to vaccinate should be decided in consultation with your veterinarian. Generally, dogs living in or traveling to high-risk areas may benefit from vaccination, especially if they spend a lot of time outdoors.
We recommend testing your dog for Lyme disease before vaccinating. Some people worry that vaccinating an infected dog could worsen symptoms, but this concern comes from outdated human vaccine experiences and has not been shown to apply in dogs.
