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Parasite prevention is extremely important for your dog. Ectoparasites like ticks can be particularly problematic because they can cause skin disease and can carry blood-borne pathogens that can make your pup very sick.
How do dogs get ticks? What diseases can they carry, and what is the best way to prevent ticks from biting your dog?
Ticks are known for hiding in dense, woody forests and areas with tall grasses. When waiting for a new host to walk by, ticks will go to the top of a plant and move their arms back and forth, also known asquesting. If your dog brushes past, the tick can let go of the plant and fall onto your dog’s hair coat. Ticks must do this because they cannot jump or fly. Certain tick species like the Brown Dog tick can infest your home and will climb up the walls in search of a host.
Once a tick has established a host, it bites the host’s skin. To do this, it has a long mouthpart known as astoma, and it buries the stoma into the skin, thus creating a very strong anchor and can make tick removal difficult without the proper tools.
Ticks can remain attached for 48 to 72 hours, feeding on blood very slowly. It can be difficult to identify attached ticks because they are very small and good at hiding in areas on your pup that are not easy to see, e.g. inside of the ears, in between toes, or even inside his mouth!
Bacteria can be transmitted from the tick to your dog while the tick is feeding, especially if you try to remove the tick and end up squeezing the tick’s body. There are several possible bacterial infections that dogs (and humans) can develop from tick bites, and many of them can cause similar clinical signs.
This is one of the most common tick-borne illnesses that come to mind when discussing tick bites. Lyme disease is caused by the bacteriaBorrelia burgdorferi. It can affect animals and humans. The most common species of tick known to carry the bacteria for Lyme disease is the deer tick which is located in many parts of the United States but predominantly in the Northeastern and upper Midwestern regions.
Lyme disease can be transmitted within the first four to six hours of being bitten, but it can take up to three weeks for a dog to have a positive test. Most veterinary clinics carry a blood test that can detect antibodies within minutes.
Dogs with positive tests yet no clinical signs may have been previously infected. Positive dogs with active clinical signs may experience fever, intermittent lameness, joint inflammation, swollen lymph nodes, lethargy, and inappetence. Lyme bacteria can also cause acute kidney inflammation which, if left untreated, can be fatal.
Remember that even though Lyme disease can cause a “bullseye” rash in humans once a tick has bitten them, dogs may not develop this same skin rash. Therefore, if your dog has been bitten by a tick, try to carefully remove the tick and bring it to our veterinarian for identification. Make sure to bring your pup along with you for an examination! Many dogs with Lyme disease respond well to an antibiotic known as doxycycline, and your vet may prescribe it for a minimum of four weeks.
Ehrlichiosis is caused by theEhrlichia canis bacterium. It is carried by various tick species but is most commonly caused by the brown dog tick, and it is considered an endemic disease in the southeastern and southwestern states. Tests that are used to detect Lyme disease will also detect ehrlichiosis antibodies.
Ehrlichiosis can cause fever and loss of appetite like Lyme disease. It can also cause bleeding problems due to its effect on red blood cells and platelets, and it can cause blindness and brain inflammation in severe cases. Hospitalization and supportive care are critical in these cases, and dogs with severe anemia and low platelets will require a blood transfusion along with doxycycline for at least four weeks.
Babesia infections are known to occur when deer ticks bite dogs, but there is also evidence of transmission via dog-to-dog contact. This is known to occur through bite wounds or through the placenta of a pregnant dog. Certain Babesia species likeBabesia gibsoni will primarily impact pit bull terriers.
Dogs who are sick from babesiosis may have a fever and become acutely lethargic. They can have pale gums, swollen lymph nodes, dark urine, and jaundice. Unlike ehrlichiosis and Lyme disease, there is no simple lab test. It is possible to see the parasite on a blood smear, but in some cases, PCR testing is necessary because it can detect all fourBabesia protozoan species.
Dogs with babesiosis may require aggressive supportive care. A special anti-protozoal medication known as imidocarb dispropionate is also prescribed, and for best results, it may be combined with an antibiotic like clindamycin or azithromycin and other anti-parasitic medications like atovaquone1.
Similar to the other diseases on this list, hepatozoonosis most commonly occurs in the Southern and Southeastern U.S. However, instead of being transmitted by a tick bite, this protozoan is transmitted when a dog ingests a tick!
There are two different species:Hepatozoon americanum (transmitted by the Gulf Coast tick) andHepatozoon canis (transmitted by the brown dog tick). In both cases, the tick carries the protozoan and will then release it into a dog’s gastrointestinal tract once the tick has been ingested.
This results in swollen lymph nodes, bleeding problems, and problems associated with the liver, lungs, and pancreas. In the case ofH. americanum, dogs will develop large, painful muscle cysts and inflammation whereas those infected withH. canis will not.
While theBabesia protozoan invades red blood cells, theHepatozoon species will invade white blood cells. In some cases, this can be seen on a microscope slide. Blood work values may appear abnormal such as a low red blood cell count, a high white blood cell count, low blood protein, and increased muscle enzymes. Definitive diagnosis is achieved via PCR testing and sometimes muscle biopsy.
It can be difficult to detect ticks on your dog, and by the time you’ve found it, it may already be too late! Ticks can transmit disease once they’ve been feeding for several hours, and if you accidentally squeeze the tick while removing it or leave the stoma under your dog’s skin, you increase the chances of causing infection. Careful removal with tweezers or a small device known as the Tick Twister is recommended.
Make sure to talk to your veterinarian about tick prevention, especially if you live in an area where ticks are prevalent! Products like Bravecto, Nexgard, Simparica, and Credelio are extremely effective at killing ticks. Collars and topical products like Frontline Plus and Advantix can help repel ticks.
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Tick-borne illnesses can cause significant illness and can be difficult to diagnose at first because the associated clinical signs can mimic other diseases. There can be long term and irreversible damage in some cases, and dogs with one form of the disease can become re-infected or can develop different tick-borne illnesses. Remember that tick prevention is important for all dogs!
Sources
Llera, R. and Ward, E. “Babesiosis in Dogs.” From the VCA website. Last accessed on 18 May 2020,https://vcahospitals.com/know-your-pet/babesiosis-in-dogs
Barnette, C. “Hepatozoonosis in Dogs.” From theVCA website. Last accessed on 18 May 2020,https://vcahospitals.com/know-your-pet/hepatozoonosis-in-dogs
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Meet The Author
Dr. Erica Irish
Erica has worked in the veterinary field since 2006, starting out as a veterinary technician before graduating from the UF College of Veterinary Medicine in 2013. As a general practitioner in an animal hospital, she has many interests and is especially interested in dermatology, cardiology, internal and integrative medicine
