Ticks are external parasites that require a blood meal to progress through their life cycle, making them a concern for both humans and pets. The question of whether these arachnids prefer dogs or people does not have a simple answer. Host preference depends highly upon the specific species of tick, its life stage, and the sensory cues it detects.
How Ticks Locate Potential Hosts
Ticks do not fly or jump; they employ a passive hunting strategy known as “questing” to find a host. During questing, the tick climbs onto low-lying vegetation and holds its front legs outstretched, waiting for a host to brush past.
The tick’s primary tool for sensing a meal is the specialized Haller’s organ, located on its front legs. This organ functions as a sophisticated chemoreceptor, allowing the tick to detect minute environmental changes. Ticks use it to sense the host’s breath by detecting exhaled carbon dioxide, body heat, moisture levels, and chemical signals like ammonia and lactic acid released in sweat. Once these signals are detected, the tick is ready to latch on when physical contact occurs.
Host Preference Varies by Tick Species
The choice between a human and a dog is primarily determined by the tick’s species and its stage of development. The blacklegged tick (Ixodes scapularis), also known as the deer tick, changes its host preference throughout its life cycle. Larval and nymphal stages typically feed on small mammals, such as white-footed mice. Nymphs are responsible for the majority of human infections because they are active during summer and are difficult to detect. Adult deer ticks prefer large mammals like white-tailed deer for reproductive success, but they readily attach to both dogs and humans.
The American dog tick (Dermacentor variabilis) received its common name because adults frequently target medium-sized carnivores, including domestic dogs. While dogs are their preferred host, adult American dog ticks are commonly found feeding on humans, particularly in grassy or scrubland areas.
The lone star tick (Amblyomma americanum) is an aggressive, generalized feeder that does not exhibit a strong host-specific preference. All three motile stages—larva, nymph, and adult—will bite humans, dogs, livestock, and wildlife. Unlike the passively questing deer tick, the lone star tick is known to actively pursue a host.
Diseases Ticks Transmit to Humans and Dogs
Tick bites carry the risk of transmitting numerous pathogens that can cause severe illness in both humans and dogs. For humans, the blacklegged tick transmits Lyme disease, caused by the bacterium Borrelia burgdorferi, as well as Anaplasmosis and Babesiosis. The lone star tick is associated with Alpha-gal syndrome (AGS), which causes a severe, delayed allergy to mammalian meat. The American dog tick and the lone star tick are vectors for Rocky Mountain Spotted Fever (RMSF).
Dogs are susceptible to Lyme disease, which can cause lameness, joint pain, and kidney complications. Canine Ehrlichiosis and Canine Anaplasmosis are common bacterial infections transmitted by the brown dog tick and the blacklegged tick, often leading to fever and lethargy. Canine Babesiosis is a parasitic disease transmitted by the American dog tick and others, which invades the dog’s red blood cells and can cause severe anemia.
Protecting Humans and Pets from Ticks
A multi-faceted approach is necessary to minimize tick exposure for both household members and pets.
For humans, treating outdoor clothing and gear with permethrin is an effective strategy, as this insecticide kills ticks on contact and remains effective through several washes. Repellents containing DEET or picaridin should be applied directly to exposed skin.
For dogs, the most reliable protection comes from veterinary-approved products, available as oral medications or topical spot-on treatments. These products often kill or repel ticks before disease transmission can occur, a process that usually takes several hours.
Environmental control is also highly effective, as ticks thrive in tall grass and leaf litter. Maintaining a mowed lawn and clearing brush near the home reduces their habitat. After spending time in tick habitats, a thorough, full-body check is essential for both people and pets.
If a tick is found attached, remove it promptly and correctly by grasping it close to the skin with fine-tipped tweezers and pulling upward with steady, even pressure. The risk of disease transmission increases the longer a tick remains attached.