What is Lyme disease?
Lyme disease is caused by the bacterium Borrelia burgdorferi. It is transmitted to dogs through the bite of an infected tick. Once in the bloodstream, the Lyme disease organism is carried to many parts of the body and is likely to localize in joints or kidneys. The most common type of tick to carry Lyme disease is the deer tick, also known as the black-legged tick. Deer ticks are distributed across the Midwest and the eastern United States, and throughout Canada, with the highest proportion in Ontario.
Can Lyme disease affect humans?
Yes, Lyme disease can affect humans, but humans do not get it directly from dogs. Humans get Lyme disease when they are bitten by the same ticks that transmit it to dogs. For that reason, preventing exposure to ticks is important for you and your dog.
What are the clinical signs of Lyme disease in dogs?
Symptoms usually appear two to five months after infection. By this time, the disease may be widespread in the body. Signs of Lyme disease may include:
- Generalized pain
- Lack of appetite (the dog stops eating)
- High fever
- Swollen joints
- Painful lameness or limping that may appear suddenly and may shift from one leg to another; if left untreated, the limping may disappear and then recur weeks or months later
- Affected dogs are sometimes described as “walking as if they are on eggshells”
It is less common for Lyme disease to affect the kidneys, but this form is often fatal. Non-specific signs that may indicate that Lyme disease is affecting the kidneys include:
- Vomiting
- Lethargy
- Anorexia (lack of appetite)
- Weight loss
How is Lyme disease diagnosed?
Dogs with lameness, swollen joints, and fever are suspected of having Lyme disease. However, other diseases may also cause these symptoms, so blood tests are used for confirmation. General blood and urine tests are often done to assess kidney function and to look for loss of protein in the urine.
Your veterinarian can perform an antibody test in the clinic. This test detects the presence of antibodies created by exposure to the organism. A positive test is meaningful, but a negative test is not, because a dog can be infected and still test negative under certain circumstances:
- If they have not yet formed antibodies
- If they do not form enough antibodies
- If they have been infected for a long time and no longer have detectable levels of antibodies
A follow-up test, called a QC6 (Quantitative C6) test, can be done to measure antibody numbers as confirmation. Other tests are available but performed less often, as they provide varying degrees of sensitivity, including polymerase chain reaction (PCA), enzyme-linked immunosorbent assay (ELISA), and joint fluid analysis and culture.
How is Lyme disease treated?
The Lyme organism is a bacterium, so it can be treated with antibiotics. The antibiotic of choice is doxycycline (Doxirobe®, Vibramycin®), followed by amoxicillin (Amoxi-Tabs®, Amoxi-Drop®, Biomox®), then azithromycin (Zithromax®). Some third-generation cephalosporins (such as cefovecin) may also be effective. Treatment lasts four weeks. Occasionally, the initial infection will recur, or the pet will be re-infected by another infected tick.
If kidney damage is present, other treatments may also be required, such as IV fluids, blood pressure medications, anti-nausea medications, and corticosteroids.
How can I prevent my dog from getting Lyme disease?
The best way to prevent Lyme disease is to limit your dog’s exposure to ticks. Ticks are found in grassy, wooded, and sandy areas. They climb to the top of a leaf, blade of grass, or short tree (especially cedar) and wait for an approaching animal to crawl onto. You can reduce your pet’s exposure to ticks by keeping them away from thick underbrush, and keeping them on trails when you’re near wooded areas or tall grass.
Several products are available that can kill these ticks and prevent disease transmission. Some products are available over the counter, while others are only available through your veterinarian. Your veterinarian can talk to you about the best parasite control options for your dog.
- Topical preventatives are typically applied to the skin at the back of the neck. Monthly preventives include Frontline Plus® (only available in the USA) and Advantix®. Bravecto® is a newer topical preventive that lasts for three months.
- Chewable preventives are given monthly (e.g., Nexgard® and Simparica®) or every three months (chewable Bravecto®).
You can also help prevent Lyme disease by vaccinating your pet. Vaccination against Lyme disease is recommended for pets that live in or travel to areas where Lyme disease is prevalent. This vaccine is initially given twice, at two-week to four-week intervals. Annual revaccination is necessary to maintain your dog’s immunity. Your veterinarian will advise you on Lyme vaccination based on your dog’s lifestyle and individual risk assessment.
How do I remove a tick from my dog?
Check your pet immediately after they have been in a potentially tick-infected area. The deer tick is about the size of a pinhead in its juvenile stage but is more obvious in the adult phase, especially after feeding. If you find a tick moving on your pet, it means the tick has not fed yet. Remove the tick promptly and place it in rubbing alcohol or crush it between two solid surfaces.
If you find a tick attached to your pet:
- Use disposable gloves, if available, to protect your fingers from exposure.
- Have another person restrain your dog, if possible.
- Grasp the tick near the dog's skin with fine tweezers or your fingernails or a tick removal tool (e.g., Tick Twister®, Tick Key®).
- Firmly pull the tick straight out. Do not twist or jerk the tick, as doing so may cause the mouth parts to break off and remain in the skin.
See your veterinarian if you are unsure or unable to remove the tick. It is important to remove the tick as soon as possible, because the disease does not appear to be transmitted until the tick has fed for around 12 to 24 hours.
If you crush the tick, do not get the tick's contents on your skin. The bacterium that causes Lyme disease can pass through a wound or cut in your skin.
