rocky mountain spotted fever in dogs

Rocky Mountain Spotted Fever In Dogs : Common Signs, Diagnosis, & Treatment

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Sean Green

Researched & Written by

Sean Green

At EasyPet, we are committed to presenting the most accurate and up-to-date information to assist you in your pet care journey. When appropriate, we consult licensed and practicing veterinarians to fact-check our professionally written articles.

Rocky Mountain Spotted Fever in Dogs (RMSF) is a bacterial illness spread via annoying tick bites. Veterinarians find it challenging to diagnose dogs since symptoms are highly variable. 

RMSF is caused by the bacterium Rickettsia rickettsii and is most frequently transmitted from the pesky Rocky Mountain wood tick (Dermacentor andersoni), the American dog tick (Dermacentor variabilis), or the brown dog tick (Rhipicephalus sanguineus).

According to the CDC, most cases of RMSF have been documented in the contiguous United States, with North Carolina, Oklahoma, Arkansas, Tennessee, and Missouri accounting for more than 60% of cases. 

How does a dog become infected with Rocky Mountain Spotted Fever?

Infected ticks must be attached to a canine for at least 10 hours to transmit RMSF. If the tick has already been fed, the disease can be passed on in 10 minutes.

The most reasonable way to prevent dogs from contracting RMSF is to keep them away from locations in which ticks are abundant. Regular checks are needed in heavily wooded areas or areas where the grass is longer. 

There is also a wide variety of tick control products available that can help to prevent ticks from sticking to dogs in the first place. Veterinarians can advise on the best tick control products to use in specific areas.

What are the symptoms of Rocky Mountain Spotted Fever in dogs?

The symptoms of Rocky Mountain Spotted Fever in dogs can vary from mild cases to more severe. The most common symptoms include:

  • Fever
  • Lethargy
  • Loss of appetite
  • Muscle pain
  • Joint pain
  • Swollen lymph nodes
  • Rash (most often seen on the underside of the body)
  • Spinal pain

In some cases, RMSF can also lead to more severe symptoms such as:

  • Pneumonia
  • Kidney failure
  • Neurological problems

How is Rocky Mountain Spotted Fever diagnosed?

Rocky Mountain Spotted Fever in dogs can be problematic to diagnose, as symptoms can be similar to other illnesses. Veterinarians will begin with a physical examination and a look at your dog’s health history.

They will then likely recommend running some routine tests, which include:

  • Complete blood count – to look for anemia or low white blood cell count
  • Biochemical profile – to evaluate organ function such as abnormal liver function
  • Urinalysis – to check for proteinuria or hematuria
  • Thoracic radiographs (chest x-rays) – to check for pneumonia
  • Tick panel – to test for the presence of R. rickettsii
  • CSF tap (spinal fluid tap) – to look for increased white blood cells or protein
  • PCR test – to test for the presence of R. rickettsii DNA

Results that indicate Rocky Mountain Spotted Fever include a low platelet count, red blood cells (anemia), and an increased white blood cell count.

How is Rocky Mountain Spotted Fever treated?

A dog diagnosed with RMSF must be hospitalized and treated with antibiotic treatment. The most common antibiotic is doxycycline, which is usually given for 2-4 weeks.

In severe cases, dogs may also require intensive supportive care such as IV fluids and oxygen therapy.

The good news is that with prompt treatment, most dogs fully recover from RMSF.

How long does it take for a diagnosed dog to recover?

Dogs diagnosed with RMSF will start to improve within 24-48 hours of starting antibiotic treatment, though some may require hospitalization for a week or more.

What is the prognosis for dogs with Rocky Mountain Spotted Fever?

The prognosis for dogs with RMSF is generally good if the disease is caught early and treated promptly. However, dogs that develop more severe symptoms such as pneumonia or kidney failure may have a more guarded prognosis.

Frequently Asked Questions:

What is the difference between Lyme disease and RMSF?

Lyme disease is caused by a different bacterium (Borrelia burgdorferi) and is transmitted by a different type of tick (Ixodes scapularis). Lyme disease is more common in the northeastern United States, while RMSF is more common in the southeastern and south-central United States.

What are some other tick borne diseases?

Some other tick-borne diseases affecting dogs include ehrlichiosis, anaplasmosis, canine babesiosis, and bartonellosis.

What species of ticks cause rocky mountain spotted fever in dogs?

The most common tick transmits RMSF to dogs is the American dog tick (Dermacentor variabilis). Other ticks transmitting RMSF include the brown dog tick (Rhipicephalus sanguineus) and the wood tick (Dermacentor andersoni).

Can dogs pass rocky mountain spotted fever to humans?

Yes, RMSF is a zoonotic disease and can be transmitted from dogs to humans. If you think you may have been exposed, it is vital to see a doctor and mention your exposure to RMSF.

Can dogs survive Rocky Mountain Spotted Fever?

With prompt treatment, the majority of dogs make a full recovery from RMSF. Dogs with more severe symptoms such as pneumonia or kidney failure may have a more guarded prognosis.


Rocky Mountain Spotted Fever in dogs is a severe tick borne disease that can be deadly if not treated promptly. However, with early diagnosis and treatment, most dogs make a full recovery. Preventing RMSF in dogs is the best way to protect your furry friend, so talk to your veterinarian about the best tick control products for your area.

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