Rocky Mountain spotted fever (RMSF) is a life-threatening disease that is transmitted to dogs through infected ticks. It may take up to two weeks for symptoms to appear. Antibiotics such as tetracycline are used to treat the disease. Proper tick control with an insecticide such as permethrin is the best way to prevent ticks from spreading the disease to your dog, especially during tick season and in areas where ticks are most prevalent.
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Causes
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An organism called Rickettsia rickettsii, a parasite in the family Rickettsiaceae, causes Rocky Mountain spotted fever. RMSF was first recognized in dogs in the 1970s. Hard-bodied ticks such as the American dog tick (Dermacentor variabilis) in the eastern Untied States and the wood tick (Dermacentor andersoni) in the western United States are carriers of the R. rickettsii organism. Ticks acquire this organism when they feed on the blood of small mammals such as foxes and raccoons.
Transmission
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Ticks usually have to be attached to the host animal for two to five hours to transmit the disease. The tick's saliva transmits the disease during feeding. The disease is transmitted faster later in the season than earlier in the season, when the R. rickettsii organisms are slower to activate. In the subclinical stage of the infection, dogs do not show any outward symptoms. Dogs treated in the subclinical stage have a better chance of a quick recovery. When symptoms manifest, it is called the acute stage.
Symptoms
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Although carried by many other mammals, dogs and humans are the only mammals who display symptoms of the disease. Fever, loss of appetite, diarrhea, vomiting, swollen ears, joint swelling and ulcerations of the mucous membranes are common. Neurological symptoms such as stupor, dizziness and seizures are also quite common in the acute stage of the disease, and may be quite severe. Most dogs will also develop retinal hemorrhaging. Some may develop renal failure, abnormal heart rhythms and pneumonia. Sudden death is also possible.
Treatment
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If left untreated, RMSF may cause death. Prompt diagnosis and treatment are imperative for a full recovery.Tetracycline given three times daily or doxycycline twice daily is used to treat RMSF. Puppies less than six months old and pregnant dogs may be given chloramphenicol three times a day to prevent teeth being stained by tetracycline. In all but the most severe cases, dogs will respond to the medication within one or two days.
Considerations
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Most dogs diagnosed with Rocky Mountain spotted fever are under three years old. Purebred dogs are more prone to contracting the disease than mixed-breed dogs. The German Shepherd breed, because of its already lowered immunity to other rickettsiae organisms, has a particularly higher chance for contracting acute RMSF. Dogs who have successfully recovered from RMSF have demonstrated immunity to the disease.
Prevention
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Rocky Mountain spotted fever is seen most often in the plains regions, east coast and the Midwestern United States. It is usually transmitted between April and September, when ticks are most active. Controlling ticks on your dog is the main way to prevent RMSF. Tick sprays, shampoos and spot-on products containing permethrin have been proven to work well in keeping ticks at bay. Since RMSF may be transmitted to humans from ticks on their dogs, it is important not to crush ticks or remove them with your bare hands, as the disease can be transmitted to humans through contact with an infected tick's insides.
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