Signs of Lyme Disease in Dogs and How to Prevent This Tick-Borne Illness
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Lyme disease, also known as Lyme borreliosis, is caused by the bacteria Borrelia burgdorferi. The disease was named for the town of Lyme in Connecticut, where an outbreak was first described. Dogs (and humans!) can contract Lyme disease when they are bitten by a tick that is carrying the Borrelia bacterium. Ticks from the genus Ixodes, also known as deer ticks or black-legged ticks, are the usual culprits.
Lyme disease is present in North America, Europe, and Asia. In the U.S., cases have been reported in dogs in all 50 states, but the majority of infections come from the Northeast, Upper Midwest, and West Coast. The Companion Animal Parasite Council has interactive maps that allow you to view how cases are distributed across the U.S. and Canada. Simply select "Tick Borne Disease Agents," "Lyme Disease," and the year that you are interested in.
Signs and Symptoms of Lyme Disease in Dogs
The majority of dogs who are exposed to Borrelia burgdorferi will never show symptoms of illness, even if they test positive for Lyme. When symptoms do appear, they generally show up several weeks to months after the dog was bitten by the infected tick.
Common symptoms of Lyme disease include:
Lameness, possibly shifting from one leg to another
Swollen joints
Lethargy
Poor appetite
Enlarged lymph nodes
Untreated Lyme disease infections can lead to kidney failure, central nervous system abnormalities, and cardiac issues.
Is Lyme Disease in Dogs Contagious?
Thankfully, no! Your dog can't get Lyme disease directly from another dog and can't give it directly to you. A tick has to suck the blood from an infected animal and then bite another animal to spread the Borrelia bacteria. No tick bite means no Lyme disease.
It is also important to note that the tick must be attached for at least 24 hours to transmit Borrelia burgdorferi. Removing an attached tick from your dog promptly is one of the best ways to prevent Lyme disease.
Diagnosing Lyme Disease in Dogs
Most veterinary hospitals have an in-house test that can quickly test your dog for Lyme. Two of the types of tests also test for heartworm and the tick diseases anaplasmosis and ehrlichia, so your veterinarian may refer to them as "heartworm tests" or a "four-way test."
These tests all check for the presence of antibodies to Borrelia burgdorferi in your dog's blood. Because they test for antibodies, a positive result means that your dog has been exposed to the bacterium, but not necessarily that he will ever show any symptoms. Dogs that have been treated for Lyme may continue to test positive for several years due to antibodies hanging around in the bloodstream.
Should My Dog Be Tested for Lyme?
The American College of Veterinary Internal Medicine (ACVIM) 2018 Consensus Update on Lyme Borreliosis in Dogs and Cats considered everything we currently know about Lyme disease in dogs to make recommendations for diagnosis and treatment. The panelists recommend that all dogs in areas where Borrelia burgdorferi and the Ixodes tick are prevalent should have screening tests for Lyme. Most veterinary clinics encourage their clients to do the in-house test once a year.
If your dog tests positive for Lyme on one of the in-house screening tests, whether they are symptomatic or not, the Consensus Update recommended monitoring for protein in their urine on a regular basis. This is so that your vet can catch any signs of kidney malfunction as early as possible to head off the often fatal condition Lyme nephritis.
It can take over a month for antibody levels to get high enough to register on tests. If you know your dog has been bitten by a tick, check with your veterinarian to see when to come in for a Lyme disease test and next steps for treatment if needed.
Lyme Disease Treatment for Dogs
Like any bacterial infection, Lyme disease is treated with antibiotics. The ACVIM 2018 Consensus Update on Lyme recommends treating symptomatic Lyme-positive dogs with doxycycline for at least one month.
If lameness is one of your dog's symptoms, you might be surprised that your veterinarian doesn't prescribe a pain medication. This is because the lameness is caused by the presence of the bacteria in the joints, not an orthopedic injury. If your dog's lameness is caused by Lyme disease, he will improve dramatically within 48 hours of starting treatment.
Always give the complete course of antibiotics, even if your dog seems to be feeling better. Because Borrelia burgdorferi likes to hang out in the joints, it can be difficult to get rid of, and stopping treatment too soon could leave enough bacteria alive to cause problems for your dog down the road. Dogs can be reinfected with Lyme disease multiple times.
Are There Any Chronic Long-Term Effects of Lyme Disease in Dogs?
Untreated Lyme disease infections can cause permanent damage to your dog's joints, including chronic inflammation and arthritis. This is obviously painful for your dog.
The scariest potential long-term effect of Lyme disease is Lyme nephritis. In dogs with Lyme nephritis, the Lyme-causing bacteria settle in the kidneys, causing damage and eventually kidney failure. This condition is usually fatal, and we don't know why some dogs develop it while others do not. Thankfully Lyme nephritis is fairly uncommon, but Labrador retrievers, golden retrievers, and mixes with these breeds in their heritage like Labradoodles and goldendoodles are at an increased risk.
Signs of Lyme nephritis include:
Poor appetite
Muscle wasting
Lethargy
Elevated creatinine and BUN on bloodwork
If your dog has tested positive for Lyme, especially if he is a Lab, golden, or mix of one of these breeds, you should have his urine checked regularly for protein.
More rarely, untreated Lyme disease can also cause neurological signs such as seizures and poor balance and cardiac signs such as arrhythmias or heart failure.
Preventing Lyme Disease
The ACVIM 2018 Consensus Update on Lyme recommends that the best way to protect your dog from Lyme disease is to keep him or her on a year-round tick preventive medication, especially if you live in an area where Lyme is common. Ticks can be active in temperatures as low as 40 degrees Fahrenheit, so your dog isn't necessarily safe in the winter.
There are a variety of tick preventive medications on the market, including topical medications, oral medications, and collars. There are also several vaccines on the market for Lyme disease. Discuss with your veterinarian which option is the best fit for you and your dog.
Ticks most commonly hang out in the woods and tall grass. If you take your dog on a walk in one of these areas, check him over for ticks right when you get home. This will allow you to remove and dispose of the ticks before they have a chance to bite your dog (or you!). Keep your lawn mowed short to discourage ticks from coming into your yard.
While Lyme disease can be an unpleasant and potentially dangerous diagnosis, you can protect your dog. Keep him on a regular tick preventive medication, check him over for ticks after walks in the woods or unmowed grass, and test for Lyme each year as part of his annual checkup.
