Ticks are arachnids capable of transmitting a variety of diseases to dogs and humans. Common ticks include the American dog tick, the brown dog tick, the lone star tick and the black-legged or deer tick. While these ticks are responsible for transmitting various diseases that cause rashes in humans, such as Lyme disease, only one tick-borne condition typically causes a rash in dogs -- and in humans.
More Than a Bug Bite
Rocky Mountain spotted fever, or RMSF, is a common tick-borne illness that can infect both dogs and humans. The cause of the disease is Rickettsia rickettsii, which spreads through the bites of infected American dog ticks, wood ticks and lone star ticks. In addition to depression, lethargy, anorexia, irregular heartbeat, swelling, inflammation and loss of coordination, Rocky Mountain spotted fever can cause a rashlike appearance on the skin, typically blue or purple in color. In humans, symptoms include fever, rash, headache, nausea, vomiting, muscle pain, loss of appetite and eye redness.
Not Just in the Rockies
Despite its name, Rocky Mountain spotted fever is not limited to the Rocky Mountain region. The Centers for Disease Control and Prevention reports that cases of Rocky Mountain spotted fever occur throughout most of the contiguous United States, with the majority of cases occurring in North Carolina, Oklahoma, Arkansas, Tennessee and Missouri.