Lyme Disease And Ticks


Lyme disease (Lyme borreliosis) is a zoonotic illness – it affects both animals and people.  

It is the most commonly reported vector-borne (that is, a disease transmitted by mosquitoes, ticks, or fleas) illness in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC).

Lyme disease is caused by Borrelia burgdorferi  – a worm-like, spiral-shaped bacterium. This bacterium is carried and transmitted primarily by the tiny black-legged tick known as the deer tick. These ticks live on animals, such as deer, rodents and birds. Although deer do not harbor the bacteria, certain other hosts such as white-footed mice do, and ticks pick up the bacteria by feeding on these infected hosts.

Deer ticks can be found in shady, moist areas, such as forests or grassy, wooded, marshy places near rivers, lakes or oceans. They cling to tall grass, brush and shrubs, near the ground. They can also survive in lawns and gardens, especially at the edges of woods and around old stone walls. Animals or people may be bitten by deer ticks while hiking or camping or just being in their back yards. 

Ticks Are Parasites

  • Ticks are tiny parasites that feed on blood
  • They are arachnids, relatives of spiders, mites and scorpions
  • Ticks crawl—they don’t jump, fly, or drop from trees

Ticks Come In All Sizes

  • They can be difficult to see
  • They can be anywhere from 1-5 mm long and then up to 20 mm when fully fed
  • In their immature stages, ticks can be barely visible, while adult ticks can be considerably larger

Why Are Ticks Problematic?

  • Ticks can transmit a number of diseases including Lyme disease. Talk to your veterinarian about how concerned you need to be about your dog picking up a tick-borne illness.
  • Tick-borne pathogens can be passed to humans by the bite of infected ticks. Ticks can be infected with bacteria, viruses, or parasites.
  • The disease can be difficult to detect and can cause serious and recurring health problems. Therefore, it is best to prevent infection by taking appropriate measures to prevent tick bites and, for dogs, possibly vaccinating against the disease.

When Are Ticks Active?

  • Black-legged ticks (deer ticks) can be active any time temperatures are 0°C and above, including mild days during the winter months.
  • Ticks can survive the winter hiding under snow, leaf litter and brush.

Life Cycle of the Deer Tick

  • Black-legged ticks (deer ticks) typically become infected with the Lyme-causing bacteria, Borrelia burgdorferi, during their larval stage when they feed on infected mice and ground-feeding birds.
  • The infected nymph or adult tick then transmits the bacteria to people and domestic animals when it attaches and takes a blood meal.


In 1975 numerous cases were identified in Lyme, Connecticut thus the origin of its name. Since that time the disease has been reported in humans and animals across the United States and around the world. Within the United States, it appears primarily in specific areas including the southern New England states; eastern Mid-Atlantic states; the upper Midwest, particularly Wisconsin and Minnesota; and on the West Coast, particularly northern California.

Due to multiple factors, the number and distribution of reported cases of Lyme disease have increased over time.


The signs of Lyme disease can take months to develop.

The most common signs include:

  • Fever
  • Lameness due to joint pain
  • Kidney problems

Using a combination of blood tests, physical examinations and pet history, your veterinarian can make the proper diagnosis. 


Symptoms of Lyme disease can be different from person to person. Early signs and symptoms of Lyme disease usually start 3 to 30 days after being bitten by an infected black-legged tick. Most people experience mild flu-like symptoms soon after being bitten, while a small number may have more serious symptoms, sometimes weeks after the bite.

Early signs and symptoms of Lyme disease may include:

  • Rash, sometimes shaped like a bull’s eye
  • Headache
  • Fever
  • Chills
  • Fatigue
  • Muscle and joint aches
  • Swollen lymph nodes

If left untreated, more severe symptoms may occur and can last from months to years. Severe symptoms may include:

  • Severe headaches
  • Additional skin rashes
  • Facial paralysis
  • Intermittent muscle, joint, tendon and bone aches
  • Heart disorders (heart palpitations, abnormal heartbeat), known as Lyme carditis
  • Neurological disorders (dizziness, mental confusion or inability to think clearly, and memory loss, inflammation of the brain and spinal cord, nerve pain, numbness or tingling in the hands or feet)
  • Arthritis with severe joint pain and swelling, particularly the knees and less commonly in other joints such as the ankle, elbow and wrists

In rare cases, Lyme disease can lead to death usually because of complications involving infection of the heart.

Protect your pets and family from the threat of Lyme disease. Contact your veterinarian for information on tick prevention and awareness. Your veterinarian can also help set up a tick control program for your dog.

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