Rocky Mountain Spotted Fever in Dogs

Dermacentor variablis (American dog tick)
American dog ticks are the most common cause of Rocky Mountain Spotted Fever.

Smith Collection/Gado / Contributor / Getty Images

Rocky Mountain Spotted Fever (RMSF) is a serious disease that can affect dogs of all ages, sizes, and breeds. Spread through tick bites, this infection causes a variety of symptoms in dogs and is seen all over the country. Dog owners should be aware of how to not only recognize this disease but also how to prevent it.

What Is Rocky Mountain Spotted Fever in Dogs?

Rocky Mountain Spotted Fever is carried by a tick and passed onto people as well as dogs when they are bitten. The tick needs to feed on a dog for several hours before the bacteria can be transmitted but when it does the bacteria travels to the bloodstream and reproduces in the cells of the blood vessels. This causes problems with blood flow because the blood vessels become inflamed and constricted. In humans this infection may also be referred to as Spotted Fever Rickettsiosis but this name also includes infections of Rickettsia parkeri, Pacific Coast tick fever, and rickettsialpox.

Signs of Rocky Mountain Spotted Fever in Dogs

Signs of Rocky Mountain Spotted Fever in Dogs

  • Fever
  • Decreased appetite
  • Coughing
  • Vomiting
  • Muscle pain
  • Joint pain
  • Diarrhea
  • Abdominal pain
  • Swelling of the legs
  • Swelling of the face
  • Lethargy

Rocky Mountain Spotted Fever can be difficult to diagnose solely on symptoms. Signs of RMSF can vary greatly from gastrointestinal symptoms such as vomiting and diarrhea to facial swelling and joint pain. An increase in body temperature, coughing, a decrease in appetite, and even abdominal pain can all be symptoms of RMSF. Oftentimes dogs with this tick-borne illness also report muscle pain, lethargy, and swollen legs but not every dog has every symptoms. Because of this variety of symptoms, it makes it hard to differentiate signs of RMSF from several other types of infections or ailments.

Causes of Rocky Mountain Spotted Fever in Dogs

Rocky Mountain Spotted Fever is a rickettsiosis or intracellular bacterial infection caused by the bacteria Rickettsia rickettsii. It is spread through the bites of several different kinds of ticks. The American dog tick (Dermacentor variablis) is the most common cause of this infection but the Rocky Mountain wood tick (Dermacentor andersoni) and the brown dog tick (Rhipicephalus sanguineus) can also transmit this disease.

Diagnosing Rocky Mountain Spotted Fever in Dogs

A full physical examination is performed by a veterinarian after symptoms of RMSF are exhibited. If RMSF is suspected, blood work and potentially a urinalysis and X-rays will be recommended. Blood work will look at red and white blood cells, platelets, and organ function. A special two-part test called an Indirect Immunoflourescent Assay (IFA) may also be performed.

If a dog has Rocky Mountain Spotted Fever the complete blood count (CBC) may show low levels of platelets and red blood cells, abnormal white blood cell levels depending on the stage of the infection. The organ function tests may show low protein levels along with abnormal calcium, electrolyte, liver or kidney values.

Treatment of Rocky Mountain Spotted Fever in Dogs

Since Rocky Mountain Spotted Fever is caused by a bacteria, antibiotics are used to treat this disease. Typically a three-week course of antibiotics is used to fight this serious infection. Probiotics may also be recommended to help maintain the good bacteria in the gut as well as the immune system during, and for at least one week after, the antibiotics. If left untreated it can be deadly.

How to Prevent Rocky Mountain Spotted Fever in Dogs

Ticks are the carriers of this disease so in order to prevent a dog from contracting RMSF the best things a dog owner can do are keep their dog away from tick-infested areas and use a tick preventative. Wooded areas and tall grasses are likely to house ticks so they are best avoided and tick preventative pills and collars will kill ticks that can pass on RMSF to a dog.

If a tick is found on a dog, it should be removed as soon as possible to prevent transmission of the disease. The entire tick, including the head, will need to be carefully pulled out.

Is Rocky Mountain Spotted Fever Contagious to Humans?

If a dog contracts Rocky Mountain Spotted Fever from a tick it cannot pass it on to a person. But if a tick that is carrying this bacterial infection bites a person, a person can be infected with RMSF just like a dog. The Centers for Disease Control and Prevention (CDC) considers RMSF "one of the deadliest tick-borne diseases in the Americas" so it is nothing to scoff at. The treatment for people is the same as it is for dogs and if left untreated, can be fatal.