Seven ticks in the United States are responsible for numerous diseases caused by bacteria transmitted when one of them attaches to a dog, or, in one case, when a dog eats it.
Most ticks can serve as hosts to more than one bacterium. Which ticks and bacteria your dogs are mostly likely to be exposed to depends on where you live and where you take the dogs for shows, performance events and even on vacation. It’s also affected by how you maintain your property and kennel, and whether you walk or hike with your dogs in natural areas.
The majority of dogs don’t get sick when infected ticks attach, but those that do can become extremely ill. One of the most challenging issues of tick-borne disease is that symptoms often don’t emerge for weeks or months after a tick has fed on a dog’s blood.
If you find multiple engorged ticks attached to one of your dogs, a consultation with your veterinarian, along with a blood test, can determine if your dog has been exposed to one of the many infectious agents spread by the parasites.
Hypostome in, Blood out
For a tick to transmit bacteria to a dog, it must pierce, then attach to, the skin. The tick uses two parts of its mouth, the chelicerae, to cut the skin, then inserts part of its mouth – the barbed hypostome – through the skin. It then secretes something called “cementin,” which helps anchor the tick to the dog’s skin, explains Susan E. Little, D.V.M, a parasitology professor at Oklahoma State University’s Center for Veterinary Health Sciences. The tick sucks in blood from the dog, taking in more than it can use. So, it regurgitates excess blood back into the dog. “It’s a back-and-forth exchange with the host,” Little says. And that’s one way the bacteria the tick carries gets into the dog.
“Some pathogens are in the [tick’s] saliva,” she adds. The term “pathogen” can refer to any infectious agent – a bacterium, virus, fungus, etc.
If not found and removed, adult ticks will stay attached for seven to 14 days, Little says, pulling blood from the dog the whole time.
During the entire attachment, the tick can be passing disease into the dog’s system.
And it doesn’t always take 24 to 48 hours of attachment. Some of the more dangerous agents can be in your dog’s body in less than a day.
Fortunately, veterinarians are “very good” at identifying and diagnosing tick-borne diseases, Little says. They know which ticks are living in their practice areas and what bacteria the parasites may be passing to dogs. A single blood test can identify Lyme, ehrlichia, anaplasma and heartworm, she says. To test for Rocky Mountain spotted fever or babesiosis, a vet must first have a “suspicion” of the condition, she says. Then he or she will request a tick panel to identify all pathogens or a single test for a particular one.
Remember, though, that dogs can test positive without being ill. In fact, “the majority of dogs do not develop clinical illness,” Little says, “but for some that do, it will be fatal.”
Know Your Region’s Risks
By knowing how prevalent ticks are in your area, you can help prevent your dog from contracting one of the seven major tick-borne diseases.
If you’ve been hearing more stories of dogs having ticks, being infected with various bacteria from them and getting sick or even dying, you’re not alone. “There are tons of papers” on the proliferation of ticks in the U.S., Little says. “It’s a truism” that ticks are transmitting more disease to dogs than in the past. “The number of cases has increased,” she says. “Any way you measure it, it has increased.”
The increased geographic distribution of ticks is widely due to habitat conversion, she says, and to increased numbers of white-tail deer and wild turkeys that support immature ticks. Although droughts knock back most tick populations, the brown dog tick, which lives from coast to coast and border to border in the U.S., is “very drought tolerant.”
Little says that we should only expect ticks’ habitat and numbers to increase.
However, you can decrease the odds of your dogs being hosts to ticks by “modifying the habitat right around the home to make it less tick-friendly,” she says. “Keep grass and vegetation closely trimmed.” Create a golf-course-like environment on your property, rather than a woods-like one, she recommends, and you’ll have fewer ticks on your dogs.
When you take your dogs into the woods for a hike, walk or run, remember that they’re likely to return with ticks. Hard ticks – as opposed to soft ones – are the ones that love to suck dogs’ blood. These “questing” ticks literally hang around on leaves of bushes or blades of grass just waiting for a mammal to brush by. When one does, they grab on with their clawed legs. Ticks in their larval stage must grab on at ground level, while nymphs, or pre-adults, climb into the vegetation, and adults, even higher. They use their eyesight and carbon dioxide detection to identify possible hosts.
If you have raccoons or other wildlife living on your property, keep your dogs away from them. Ticks can live on the blood of many mammals, not just dogs and people.
If ticks do attach to your dogs, you can safely remove them. Just grab the tick as close to the mouth part as possible, Little says. Devices designed just for removing ticks may be more effective than tweezers. If a tiny part of the tick remains attached, remove it as well. Do not, however, put petroleum jelly on the tick or try touching it with a hot match. “This can induce regurgitation in the tick,” Little says, increasing the possibility that it will transfer some infectious agent to the dog.
Of course, it’s best to keep dogs with any potential exposure to ticks on a preventive product regimen. “We have really good tick control products now, so I think folks should use them,” Little says. “Every dog should be on tick control every month all year ‘round. Ticks are out 12 months of the year, except in the upper Midwest in winter.”
Little points out that “adult ticks are most active in the fall,” so if you use a flea-tick preventive all summer, then stop when it cools off in the fall, your dogs are susceptible to a tick-borne disease. In addition, even in states with typically frigid winters, if the temperatures are milder than usual, dogs are at risk, she says.
“Tick control is even more important for dogs that are kept in kennels or groups,” she adds. The brown dog tick can establish “infiltrations” in kennels. “Once they’re established, they’re very difficult to eradicate.” They live in cracks in concrete or between boards. “It’s a nightmare to try to get rid of them, much worse than fleas.”
America’s Dog-Loving Ticks
The brown dog tick (Rhipicephalus sanguineus) is firmly attached to the top of the list as the tick with the most habitat in the U.S. The Centers for Disease Control and Prevention’s maps of tick populations around the country show that the brown dog tick makes its home everywhere except in one small area in northern Utah. Not only is this drought-tolerant parasite found virtually everywhere, it transmits the various bacteria that cause Rocky Mountain spotted fever, ehrlichiosis and babesiosis, and is suspected of passing along those associated with bartonellosis and hepatozoonosis, according to Little. That’s pretty much everything except Lyme disease and anaplasmosis.
Brown dog ticks, bad. Prevention, good.
No other tick comes close to the brown dog tick’s prevalence, but the American dog tick (Dermacentor variabilis) lands in second place, living in more than half of the country. Only Washington, Idaho, Utah, Colorado, Nevada, Arizona and New Mexico are free of the American. It’s moving into Oregon, Montana and Wyoming, according to the CDC, and is well-established in every other state. The American bests the brown dog tick, though, as the most common host for R. rickettsii, the bacterium that causes Rocky Mountain spotted fever.
American dog ticks, bad. Prevention, good.
Number 3 is the blacklegged tick (Ixodes scapularis), more commonly known as the deer tick. Its smaller geographic spread is in the Southeast, East Coast and around the Great Lakes states. Although it doesn’t have the largest spread, the deer tick is a host to multiple bacteria with potential to cause many diseases. It carries Anaplasma phagocytophilum, the bacterium which leads to anaplasmosis;Babesia microti, the cause ofbabesios;Ehrlichia chaffeensis andEhrlichia ewingii, the bacteria responsible for ehrlichiosis; and Borrelia burgdorferi, the culprit in Lyme disease. However, B. burgdorferi is not present in every region where the deer tick lives, according to the CDC. These ticks are typically at the nymph or pre-adult stage when they transmit Babesia microti. Deer tick nymphs are about the size of a poppy seed.
Deer ticks, bad. OK, OK, you get the idea.
Next comes the Lone Star tick (Amblyomma americanum) whose range is limited to the Southeastern and Eastern U.S. If you live in these areas, your dogs are susceptible to erhlichiosis and Rocky Mountain spotted fever when a Lone Star attaches.
The Rocky Mountain wood tick (Dermacentor andersoni) unsurprisingly is found in the Rocky Mountain states and transmits R. rickettsii, which causes Rocky Mountain spotted fever.
The Gulf Coast tick (Amblyomma maculatum) was historically a seaside resident. Although still concentrated along the Atlantic coast and the Gulf of Mexico, it has moved well inland, Little says. It’s now in Oklahoma and Arkansas, as well as in non-coastal areas of the South and the Southeast, and throughout Florida. It transmits R. parkeri, which causes a form of spotted fever, according to the CDC, but dogs are infected when they eat the tick, rather than when it feeds on dogs’ blood.
Number 7 on the tick list is the Western blacklegged tick (Ixodes pacificus), which spreads the bacteria that can lead to anaplasmosis and Lyme disease. It populates the smallest area of all seven ticks in the country – the West Coast, part of Utah, small areas of Arizona and Nevada, and an inland part of Oregon.
If that’s not enough to convert you to year-round tick preventive use, we don’t know what is.
To see an excellent chart of ticks at their various stages, cross-referenced with the regions in which they live, visit the TickEncounter Resource Center.
A future article will delve into the diseases which can result when these ticks attach to a dog and pass infectious agents into its body, and explore the clinical signs, treatment and prognosis for each.