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Tick-borne disease is a growing threat to both canine and human health. Ticks are parasites that attach themselves to animals and people, feed on blood, and transmit diseases directly into the host’s system. The disease occurs when an infected tick bites a dog or a human and transmits the disease into the victim’s body.

The geographic distribution of ticks is changing due to climate change, de-foresting, and the changing living and migrating patterns of deer, birds, and rodents. This can vary yearly or even by season. Ticks are in virtually all parts of the United States, including some urban areas, and many parts of the world. They present a danger to both people and pets.

The most important tick-borne diseases that affect dogs are Lyme disease, Ehrlichiosis, Anaplasmosis, Rocky Mountain Spotted Fever, Babesiosis, Bartonellosis, and Hepatozoonosis. All can have serious health consequences for dogs and many can have serious health consequences for people as well.

Lyme Disease

Lyme disease is an infectious disease caused by a spirochete bacteria (Borrelia) carried by the Black-Legged Tick (more commonly known as the Deer Tick). Lyme disease has typically been associated in the Northeast and upper Midwest areas of the United States, but we are now seeing it also on the west coast (Washington, Oregon, and California), as well as in Florida. In fact, Lyme has been detected on dogs in many parts of the country and also in some areas of southern Canada. The tick has to be attached to its host for about 36-48 hours for transmission of bacteria into the host, and signs of illness occur about 2-5 months after a tick bite.

It’s important to do a thorough check for ticks and remove them promptly after a walk in the woods or other grassy or shaded areas where ticks may reside. In urban areas, that may include your local dog park.

Signs of Lyme disease may include fever, lameness, limping, joint pain/swelling, enlargement of lymph nodes, and lethargy. Lyme disease can progress to kidney disease, which can become fatal. (Unlike Lyme in humans, dogs do NOT develop a “bull’s eye” rash.)

Lyme disease is usually diagnosed via blood tests. The initial test detects exposure to the tick-agent and helps the veterinarian determine additional testing as needed.

The treatment of a dog that is positive on the initial test but is otherwise healthy remains controversial amongst some veterinarians. When the decision to treat a dog with Lyme is made, dogs are usually placed on antibiotics for 28-30 days.

There is a vaccination for Lyme disease and plenty of other tick preventatives. Though some question its duration and efficacy, the vaccine may reduce the rate and severity of the illness should it appear. Dog owners should speak to their veterinarian to determine if the vaccine is appropriate for their pet.

Canine Ehrlichiosis

Canine Ehrlichiosis is found worldwide. It is caused by several types of ticks: The Brown Dog Tick, Lone Star Tick, and American Dog Tick. Signs include fever, poor appetite, and low blood platelets (cells that help the clotting of blood), often noted by nose bleeding or other signs of bruising or anemia. Signs start about 1-3 weeks after the bite of an infected tick. Dogs diagnosed and treated promptly can have a good prognosis, but those who go on to the chronic phase have more difficulty recovering.

Border Collie puppy playing in tall grass.


Anaplasma is a disease caused by a bacterium carried by the Black-Legged Tick (Ixodes). Though Anaplasma can be seen worldwide, there are two Anaplasma species that are known to detect disease in North American dogs:

  • Phagocytophilum:  Northeast and the upper Midwestern United States,
  • Platys: California and coastal states.

The signs are similar to Lyme disease, though dogs with Anaplasma often have low blood platelets cause bleeding disorders.

Rocky Mountain Spotted Fever

Rocky Mountain spotted fever is one of the more commonly known tick-borne diseases to affect dogs and humans. It is carried by the American Dog Tick and the Rocky Mountain Wood Tick, as well as the Brown Deer Tick. This disease has been found in much of North, South, and Central America. Signs include fever, poor appetite, swollen lymph nodes, and joint pain. Low platelets, which help in blood clotting, are often found. On occasion, neurological signs such as wobbliness can also occur.


Babesiosis is another disease caused primarily by the bite of a tick, but can also transfer from dog bites, transplacental transmission and possible through contaminated IV blood. The main issue associated with Babesiosis is “hemolysis,“ or the breaking down of red blood cells. Symptoms include lethargy, pale gums, dark-colored urine and jaundice (yellow/orange colored skin or sclera — the “whites” of the eyes).


Bartonella is an emerging infectious disease in dogs, as well as cats and humans. It has also been known as cat scratch disease (CSD). Most infections usually occur after scratches from domestic or feral cats who have been infected from fleas. CSD can occur wherever cats and fleas are found.


Hepatozoonosis is slightly different, in that the infection is acquired after a dog ingests an infected tick. This disease is not zoonotic; in other words, people cannot catch this from infected dogs. This disease is generally found in the southern United States. Signs of the disease are pain and reluctance to stand or move, fever, muscle wasting, and mild to moderate anemia. This disease is severely debilitating and often fatal.

How To Prevent Tick-Borne Disease

These diseases can present a serious risk to the health of dogs and to people. It’s important that dog owners talk with their veterinarian to determine the best approach to flea and tick control.

Further information can be found through the American Kennel Club’s Canine Health Foundation.

A map showing the prevalence of Lyme disease can be found at the Center for Disease Control.
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