Rocky Mountain Spotted Fever in Dogs

Rocky Mountain spotted fever is a tick-borne disease that affects both dogs and humans. It can cause serious and permanent damage to the nervous system. Here's what you should know about this disease.

Causes and Transmission of Rocky Mountain Spotted Fever

Rocky Mountain spotted fever is caused by infection with a rickettsia organism. Rickettsia organisms are classified somewhere between bacteria and viruses. The particular rickettsia organism that causes Rocky Mountain spotted fever is called Rickettsia rickettsii.

R. rickettsii spreads through the bite of the Rocky Mountain spotted fever tick, and through the bite of the American dog tick. It can't be passed from animal to animal, from animal to human, or from human to human. Transmission must occur through the bite of an infected tick. The tick must remain on the host for between 5 and 20 hours before the rickettsia organism can spread to the host. Most cases of Rocky Mountain spotted fever occur in the summer, when tick bites are most likely.

Symptoms of Rocky Mountain Spotted Fever

Rocky Mountain spotted fever is a disease that occurs in two stages. In the first, or subclinical stage, dogs don't show any symptoms of the disease. Laboratory tests may uncover the presence of the infection. Treatment is usually easier in this stage of the disease.

Symptoms appear in the second, or acute, stage of the disease. Symptoms are often vague and include:

  • Depression
  • Muscle and joint pain
  • Loss of appetite
  • Fever
  • Edema 
  • Swelling of the lymph glands
  • Arrhythmia
  • Pneumonia
  • Stupor
  • Seizures
  • Dizziness
  • Diarrhea
  • Vomiting
  • Retinal hemorrhages
  • Renal failure
  • Anemia
  • Ulcers in the mucous membranes
  • Increased production of liver enzymes

If your dog catches Rocky Mountain spotted fever, his symptoms will most likely develop 2 to 14 days after he's bitten by the infected tick.

Diagnosing and Treating Rocky Mountain Spotted Fever

Your vet will need a thorough physical exam and complete medical history in order to diagnose your dog with Rocky Mountain spotted fever. If you have recently traveled with your dog, tell your vet, since Rocky Mountain spotted fever is more prevalent in some regions than others. 

Blood tests are available to test for antibodies to R. rickettsii. Other blood tests can help your vet evaluate how the infection is affecting your dog's internal organs and nervous system.

Treatment for Rocky Mountain Spotted Fever involves administering antibiotics. Your vet may prescribe enrofloxacin, tetracycline or doxycycline. Treatment lasts for 10 to 14 days; most dogs recover quickly if they receive treatment right away. If your dog's case is serious enough to cause nervous system damage, however, he may never completely recover. 

Dogs that have recovered from the disease sometimes enjoy a long period of immunity. As of yet, no vaccine for this disease exists.

Preventing Rocky Mountain Spotted Fever

The best way to keep your dog safe from Rocky Mountain spotted fever is to make sure he doesn't get ticks. Tick collars and one-spot tick repellents are both good options. Because rodents are vital to the life cycle and development of the ticks that spread Rocky Mountain spotted fever, rodent control can help with tick control.