Overview of Ticks
Ticks are eight-legged, blood-feeding ectoparasites that are closely related to spiders, scorpions, and mites and live on mammals and birds. There are about 800 different species of ticks.
Ticks are relatively large (compared to fleas and mites), with soft rounded bodies. Most ticks attach to their host and feed for as long as 12 to 24 hours before they fall off. Young ticks (nymphs) may feed on one host, drop off, and then feed on a different host as adults. Most ticks spend about 10 percent of their lifetime attached to their hosts.
Individual tick bites can cause local reactions in pets and in humans, including skin damage, irritation, inflammation, and hypersensitivity. A large number of tick bites can cause anemia. Some ticks secrete toxic saliva that can cause paralysis. All ticks can carry and transmit disease.
Lyme disease (lyme borreliosis) is caused by the bacteria Borrelia burgdorferi and is spread by the deer tick. It is one of the most common tick-transmitted veterinary diseases in the world.
In pets, Lyme disease can affect both cats and dogs. Its most common clinical symptoms are arthritis, lameness, anorexia (loss of appetite), and depression. It can also cause cardiac, neurological, and kidney disease.
Canine ehrlichiosis (tick-borne fever) is caused by Ehrlichia canis and is spread by the brown dog tick Rhipicephalus sanguineus. It occurs throughout the United States, but is most common in the Southeast. Ehrlichiosis damages and decreases the production of blood cells and leads to anemia, lowered disease resistance, and abnormal bleeding.
Diagnosis is usually based on a blood test. Treatment involves antibiotics and supportive care. Though the prognosis is usually good, ehrlichiosis can be fatal.
Rocky mountain spotted fever is caused by the bacteria Rickettsia rickettsii and is spread by the American dog tick (Dermacentor varabilis) and the wood tick (D. anderson). In pets, symptoms include fever, lethargy, depression, anorexia, swelling, a stiff gait, abnormal bleeding, breathing problems, and eye pain. Rocky mountain spotted fever is difficult to differentiate from canine ehrlichiosis. The prognosis is good if the pet receives prompt treatment, including antibiotics and supportive care.
In July 2012, researchers in Virginia reported a rare reactiondelayed anaphylaxis to red meat following a tick bite in the Journal of General Internal Medicine. The current theory is that, in response to a tick bite, the body may produce certain antibodies to a specific carbohydrate that is present in red meat. In affected people, a severe, life-threatening allergic reaction caused by the release of histamine can occur a few hours after eating red meat. More study on this rare syndrome is needed.
If pet owners find a tick on their dog or cat, they should remove it by grasping the tick with fine-pointed tweezers and gently pulling it free. The more quickly the tick is removed, the lower the risk of disease transmission to the pet.
Preventive Tick Control
Preventative control of ticks is difficult. Acaricidal collars (e.g., Preventic) and topical acaricides (e.g., Frontline) are among the most common devices used. Acaracides are pesticides that kill ticks and mites. Treating the pet's environment usually requires a professional exterminator.