What Does a Tick Look Like?

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PetMD Editorial
Published: August 29, 2017

What Does a Tick Look Like?


By John Gilpatrick


They say that good things come in small packages, but that’s definitely not the case for the little monsters we call ticks. These nasty critters suck on our blood and carry with them the possibility of transmitting several serious illnesses, including Lyme disease.


According to Dr. Tom Nolan, director of the Clinical Parasitology Lab at the University of Pennsylvania’s Ryan Veterinary Hospital, ticks are related to spiders, so they all have eight legs, a head, and an oval-body section to which the legs attach.


“The larval and nymphal stages are small—the size of a freckle or a poppy seed—and the unfed adults are about 5 millimeters long and flat,” he says. “A fully fed female adult tick can be the size and shape of a small grape.”


Not all ticks are created equal. Some are more dangerous than others. Knowing what species are in your area—and what each looks like—is important if you want to get your pets the medical tests or treatments they might need.


Here’s how to identify the four most common ticks in America.

Black-Legged Tick


Also known as the “deer tick,” the black-legged tick is the most common species that affects small animals in the Northeast and Mid-Atlantic states, according to Dr. Matthew Frye, extension educator for the New York State Integrated Pest Management Program at Cornell University.


“This tick is found in shrubs and in the woods, and it quests for its hosts, which means it stands on vegetation or on a leaf with its legs up and out, and when an animal walks by, it attaches,” Frye says.


Frye notes that it only quests at about one-and-a-half feet above the ground or lower, which means humans are usually only affected below the thigh, but dogs and cats can get them all over.


Black-legged ticks, unlike most other species, can carry Lyme disease. If you spot one, it’s important to take action right away. “In the case of Lyme disease, ticks don't begin to inject the causative pathogen until they've been attached to the host for 24 to 48 hours,” Nolan says. “If deer ticks can be removed early, one stands a good chance of ‘interrupting’ transmission of the Lyme disease agent.”


What are some of this tick’s defining characteristics? As you might expect from the name, it has black legs. The body may be red or brown and is relatively small—often about the size of a sesame seed unless the tick has recently fed.

American Dog Tick


This tick, Frye says, is quite a bit bigger than the deer tick. It’s also lighter in color than the deer tick— usually brown, but it turns shades of gray when engorged with blood. Its legs are lighter than its body. They most commonly take up in sun-soaked areas, like your lawn. For this reason, it’s a little unusual that the American dog tick is also known as the “wood tick.”


Nolan says the most common concern with this species of tick is the transmission of Rocky Mountain spotted fever, a serious and potentially fatal illness that can cause fever, lethargy, enlarged lymph nodes, limping, coughing, difficulty breathing, vomiting, diarrhea, and bruising and bleeding.


American dog ticks populate the East coast and Midwest primarily, though some are found on the California coast as well, according to the CDC.

Lone Star Tick


Like American dog ticks, the lone star tick carries the pathogen for Rocky Mountain spotted fever, Frye says.


“It’s more of a southern species at this point, but there are some in New York, specifically the Hudson Valley and Long Island,” he says. “And as it’s moving west and north, it’s becoming more prevalent.”


In terms of coloring, this tick is similar to the American dog tick. The most identifiable difference is the single white dot—which resembles a “lone star”—on the back of the adult females.

Brown Dog Tick


This tick is distributed across the entire world because, unlike most other species, it can complete its entire life cycle indoors. For that reason, Frye says, it’s most commonly found in places where there are a lot of dogs, such as kennels and shelters.


This tick also transmits Rocky Mountain spotted fever, but Nolan says dogs can also contract a disease called Babesia canis, which infects the red blood cells and can lead to anemia. The brown dog tick is also the primary vector for ehrlichiosis in dogs, a disease that is similar to Rocky Mountain spotted fever.


They’re also dark brown, but like American dog ticks, they can swell up to be quite large when engorged, and they may also turn gray.

How to Remove at Tick


So, you’ve identified the type of tick on your pet, and you want to know what to do next. The good news is that for all the different colors, patterns, locations, and diseases among species of ticks, there’s a single uniform way to remove them from your pet’s skin.


“The best way is to use really sharp, fine-tipped tweezers,” Frye says. “Get close to the skin, and gently pull the tick straight out.”


Anything that irritates the tick, he adds—including twisting, burning, or coating it in Vaseline—could cause it to regurgitate its gut and salivary contents, which increases the risk of tick-borne disease transmission. Consult your veterinarian to discuss the risks that tick bites might pose to your pet and to formulate a safe and effective parasite prevention plan.