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Cornell Richard P. Riney Canine Health Center

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Lyme disease

Protection against Lyme disease is focused on tick control and vaccination. 

Lyme disease is a bacterial infection spread by ticks, and it affects both dogs and humans. It is most common in the Northeast, mid-Atlantic, and upper Midwest, although the range has been increasing in North America. While ticks are often associated with warmer weather, they can be active year-round if the temperature is above 40°F.  


Lyme disease is caused by the bacteria Borrelia burgdorferi, which lives inside a specific type of tick called a black-legged tick, or deer tick. These are very small ticks, ranging from the size of a poppy seed to a sesame seed.  

After a tick carrying the Lyme bacteria attaches to skin, it takes at least 24-48 hours before transmission occurs. Prompt removal of ticks can help avoid Lyme infections.   

Clinical Signs 

Most dogs exposed to Lyme will not become sick. For those that do become sick, symptoms often do not occur until 2-5 months after a tick bite.  

The most common signs of Lyme disease include: 

  • Fever 

  • Lameness 

  • Lethargy 

  • Decreased appetite 

  • Joint swelling and pain 

  • Swollen lymph nodes

A less common but serious complication associated with Lyme disease causes kidney damage (Lyme nephritis). This may be more likely in young-to-middle aged Retrievers. The clinical signs for Lyme nephritis are far more severe than the typical Lyme infection and include vomiting, not eating, increased thirst and urination, weight loss, extreme lethargy and more. 


Lyme can be diagnosed based on the common clinical signs in combination with a relatively inexpensive and quick blood test that determines the presence or absence of antibodies. The timing of the test can affect the results due to how long it takes for antibodies to develop; therefore, testing should be delayed at least 4-8 weeks after a tick bite. 

If your dog is diagnosed with Lyme, your veterinarian may recommend a urine test to screen for kidney health. While it is an uncommon consequence of Lyme disease, if there are already apparent clinical signs of kidney disease, blood work and additional testing will likely be recommended to determine if it is Lyme nephritis. 


Lyme disease is treated with antibiotics, most commonly doxycycline, for four weeks. Pain medications should also be given to help with joint discomfort. Asymptomatic dogs generally only require monitoring by you and your veterinarian, which may involve routine urine checks. 

In cases of Lyme nephritis, the treatment will involve hospitalization and addressing severe kidney disease with IV fluids, medications to help with protein loss and nausea, blood pressure management, nutritional support, antibiotics, immunosuppressive drugs and more.  


The majority of dogs positive for Lyme will not become sick. For those that are sick, most dogs respond within 1-2 days of starting antibiotics. 

However, dogs that develop Lyme nephritis have a poor prognosis and many do not survive. 

Zoonosis and human transmission

Lyme disease can infect both dogs and humans. Humans do not get Lyme directly from dogs, but rather from the same deer-ticks that can infect people. Limit the opportunities for your pet to bring ticks into your spaces by implementing tick control measures.  

Make sure to check both of your bodies for ticks after being in areas with a high prevalence, as well as after being in tall grass, forest litter and brushing against other vegetation.  


The best ways to avoid Lyme disease in dogs include: 

  • Year-round tick control 

  • Routine tick checks 

  • Prompt removal of ticks  

  • Avoid high risk areas (tall grasses, wooded areas) 

  • Vaccination 

Tick control is the most important part of Lyme disease prevention and must be done consistently and properly. There are many products available such as collars, topicals or chewables. Your veterinarian can help guide you on what is the best choice for your dog.  

Since Lyme disease transmission from a tick bite takes at least 24-48 hours, tick checks and prompt removal are crucial to avoid infection. If a tick is found attached to your pet, it can be removed by grasping it close to where it is attached to the skin with tweezers or a tick removal device with slow and steady traction. Keeping lawns cut short and cleaning up leaf piles can help dogs avoid ticks in the backyard. 

Discuss with your veterinarian if the Lyme vaccine is right for your dog based on location, risk and lifestyle. Previous Lyme infections do not provide natural immunity, and the vaccine can help prevent re-infection. Even with vaccination, tick preventatives should be used year-round in order to minimize the risk of infection. The Lyme vaccine is given once, followed by a booster after 3-4 weeks and then again annually. 

Additional Cornell resources

The university's New York State Integrated Pest Management Program provides tick identification and prevention resources.

Cornell Cooperative Extension also offers additional information about ticks and tick-borne diseases like Lyme.