Updated March 9, 2023 – As summertime approaches and we increase time spent enjoying the outdoors, it's important to remember that ticks, and the diseases they carry, can become a concern for pets and their people.
Tick-borne diseases are a subset of vector-borne diseases, meaning that an intermediate host (often an insect) is involved in transmitting an organism to another host. Diseases are spread when a susceptible host (e.g., a dog) is exposed to an infectious organism, usually through a bug bite. In most cases, the vector is essential for transmission. In other words, many vector-borne diseases can’t be transmitted from dog to dog or dog to human, or vice versa.
Ticks belong to the arachnid family of arthropods and share a lot of similarities with another notable denizen of this family – spiders. Ticks live everywhere in the United States and can carry many different pathogenic bacteria. While there are some exceptions, most tick-borne diseases that affect humans also make pets, primarily dogs, sick. There also are a few diseases that are specific to dogs. It's very rare to see tick-borne diseases in cats but there are a few that owners, even of indoor-only cats, should know about.
Whether a pet becomes ill from a tick-borne disease can vary greatly from pet to pet. Some dogs and cats recover from tick-borne diseases with little or no signs of any illness. Others become chronically infected and experience serious losses in quality of life and longevity. Determining why these diseases have a wide range of symptoms and severity is an important and active area of research. Most researchers believe an individual pet’s response is due to a complex interaction between the genetics and environment of the host, vector and pathogen.
The Big 7 Canine Tick-borne Diseases in the US
Veterinary infectious disease experts frequently refer to the following seven tick-borne diseases common to the continental United States.
Lyme disease is one of the most serious and well-known of the diseases transmitted by ticks. According to the CDC, it is the most common tick-borne disease in people and probably is the most common in dogs, too (although statistics are hard to find). The disease has never been reported in cats.
Lyme disease is caused by Borrelia burgdorferi, a bacteria transmitted by blacklegged ticks (more commonly known as the deer tick). The scientific name for the tick species that transmits Lyme disease is Ixodes.
Although once confined to the Northeast, Lyme disease has been reported in the Mid-Atlantic states, Midwest, Great Lakes states, southern Appalachia, West Coast and southern Canada.
It goes without saying that Lyme disease is a serious problem in people, too. Tick identification is important if you and your dog are outside in areas where Lyme disease is prevalent.
Anaplasmosis is a bacterial disease transmitted by two different types of ticks and involving two different species of Anaplasma organisms. The signs of this disease are the same regardless of the tick vector or species of bacteria involved. The important point for dog owners to know is that Ixodes ticks (the same type of tick that transmits Lyme disease) are responsible for transmitting the disease in the Northeast and Midwest, but Rhipicephalus sanguineus(also known as the brown dog tick) is the main vector of the disease in the south-central United States.
Although cases are higher in some regions, this disease has a wide distribution across the continental United States. A few cases of this disease have been reported in cats but it's uncommon.
This bacterial infection also has a wide distribution across the United States. Several species of Ehrlichia can cause disease and many tick species, including Ixodes ticks, R. sanguineus and Amblyomma americanum (Lone star tick) can transmit these bacteria. The number of Ehrlichia species identified constantly is expanding, but all identified species cause similar clinical signs and are treated with the same medications. Once again, this disease has been reported but is very rare in cats.
Rocky Mountain Spotted Fever
This disease is one of the most serious types of tick-borne diseases due to its rapid onset and high fatality rate. Rickettsia rickettsii is the bacteria responsible, and the disease can be transmitted by many different types of ticks including R. sanguineus, Amblyomma species, Dermacentor andersoni (Rocky Mountain wood tick) and Dermacentor variabilis (American dog tick or wood tick). Dogs are much more likely to be affected than cats.
Don't be fooled by the name - this disease has a wide distribution of cases across the United States.
Babesiosis is caused by one of two species of protozoa, Babesia vogeli and Babesia gibsoni. B. vogeli is transmitted by the R. sanguineus tick and is most common in the southern United States.
B. gibsoni is a bit of an odd ball, since most transmission occurs through blood contamination when dogs are fighting. However, there is some evidence that R. sanguineus can transmit this species as well.
Although certain species of Babesia can infect cats, these species are found primarily outside the United States. The disease has not yet been seen in cats within the US.
Hepatazoonosis is a disease caused by one of two protozoal species, Hepatozoon americanum and Hepatazoon canis. Like Rocky Mountain spotted fever, hepatazoonosis often is fatal despite treatment.
Amblyomma maculatum (Gulf Coast tick) is considered the primary vector of H. americanum and, as the name implies, these ticks are more common in southern states.
The major difference between this disease and other tick diseases is it is transmitted when a dog eats an infected tick during grooming. Dogs also can be infected if they eat game that have ingested infected ticks.
H. canis recently has been reported in the United States for the first time and is transmitted by R. sanguineus. The significance of this finding is still unknown, but experts are monitoring for this pathogen.
Only one feline case of hepatozoonosis has been reported in the United States (the cat resided in Hawaii) but it has been reported in a number of other countries.
Many people may know bartonellosis by its more common name – cat scratch disease. What you may not know is there is some evidence that ticks might be able to transmit members of this family of bacteria in dogs. This finding remains controversial but many veterinary infectious disease experts are working on answering this question.
A Quick Word About Tick Paralysis
Another important condition associated with tick bites is tick paralysis. Tick paralysis is caused by a toxin present in tick saliva. When a dog gets bitten by enough ticks, the toxin in the saliva causes paralysis. Tick paralysis is a serious but treatable disease with an excellent long-term prognosis if identified and treated before paralysis of the respiratory muscles occurs.
Cats in North America seem to be resistant to tick paralysis, but the disease is a serious problem in both dogs and cats in Australia.
Diagnosis Is a Challenge
Tick-borne diseases are notoriously difficult to definitively diagnose for many reasons, including:
- Pathogens hide out in an infected individual’s cells, making them invisible to the immune system and many diagnostic tests
- Symptoms are similar to lots of other diseases
- Symptoms might not appear for months after exposure
Signs common to almost all tick-borne disease include:
- Poor appetite
- Lameness (which can shift between limbs)
Blood tests remain the backbone of diagnosis and include routine blood panel results as well as special tests.
Treatment for a tick-borne disease involves antibiotics (sometimes for many months or a lifetime in some cases) and addressing the symptoms of infection with supportive care and anti-inflammatory medications.
What You Can Do to Prevent Disease
The good news is there are many prevention strategies to keep ticks off your pets. For tick-borne diseases, an ounce of prevention truly is worth a pound of cure and may even save your pet’s life!
Daily tick checks, especially if you’re hunting or camping with your dog, are vital to preventing disease transmission because ticks must attach for 24-36 hours before they can introduce most diseases to a host.
Another important source of tick exposure for pets and humans is at the interface with wild animals, so limiting your dog’s access to wildlife can minimize tick exposure.
If you find a tick, carefully remove it and put it in rubbing alcohol for disposal. Remember that ticks can be very small so you may not find all of them just by looking and feeling – a fine-toothed comb can help uncover these tiny hitchhikers. Brushing your cat daily, especially if they go outside, is a good way to find ticks.
Ticks tend to live in tall grass and brushy areas so keeping your dog (or cat) on the trail (or inside) will help mitigate exposure. Keeping your grass cut and trimming and removing brush from your yard can take away important tick hiding places.
Pharmaceutical preventives are available, including a variety of medications and vaccination. It’s important to talk to your veterinarian to devise the best prevention strategy for your dog or cat based on location, lifestyle, activities such as hunting, hiking and water sports, and relative risk of infection.
Critical Data from the Golden Retriever Lifetime Study
Morris Animal Foundation’s Golden Retriever Lifetime Study is one of the largest studies of its kind in the world. Our team is monitoring all health outcomes in our cohort of 3,044 dogs, including any confirmed cases of tick-borne disease as well as statistics on tick prevention, test results and regional demographics.
As of June 2021, 178 dogs in the study had at least one tick-borne condition noted by their family veterinarian. In some dogs, this could simply indicate a positive test result on screening, or it could indicate disease. We’ll be monitoring this closely as the Study progresses over the next few years, providing an important window into the incidence of tick-borne diseases and outcomes for the Study dogs.
How We’re Helping
The Foundation has been supporting research on tick-borne diseases since 1963! We've funded several studies looking at not just ticks but all kinds of vector-borne diseases. Learn more about what we’re doing to help animals live longer, healthier lives!
An excellent source for more information about important tick species, where they live and the diseases they carry, is the Centers for Disease Control and Prevention. They have detailed maps that show the regions where certain diseases are most prevalent.