Symptoms of Rocky Mountain Spotted Fever
By Jessica Vogelsang, DVM
After an unusually wet winter, this spring promises many things: amazing wildflowers, tall grasses and plenty of ticks. Ticks are more than just gross: they transmit a variety of diseases that can infect both humans and pets. Rocky Mountain Spotted Fever is one particularly nasty tick-borne disease that affects both dogs and humans.
Rocky Mountain Spotted Fever (RMSF) is caused the bacterium Rickettsia rickettsii. RMSF is transmitted through the bite of an infected tick. In North America, the types of tick usually associated with the disease are Dermacentor and Rhipicephalus species; common names include Rocky Mountain wood tick, American dog tick and the brown dog tick. These ticks are widely distributed east of the Rocky Mountains and are also seen on the Pacific Coast.
Both dogs and humans can suffer from Rocky Mountain Spotted Fever. Although both species can develop the disease, a bite by an infected tick is required for transmission of disease, so dogs cannot infect humans directly and vice versa. While cats may test positive for exposure to Rickettsia, they are not thought to develop the clinical signs of RMSF.
In dogs, there are no telltale signs that specifically point to RMSF as a cause of illness. Because the organism damages the walls of small blood vessels, clinical signs develop throughout the body. The clinical signs can be vague and mimic other disease processes, which may delay diagnosis and the start of treatment. Common symptoms include: