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Rickettsia Tick Borne Disease in Dogs

Rocky Mountain spotted fever is one of the most commonly known tick-borne diseases to affect dogs and humans. It belongs to a class of diseases known as Rickettsia; rod-shaped microorganisms that resemble bacteria, but which behave like viruses, reproducing only inside living cells. Rickettsia rickettsii -- the organism responsible for Rocky Mountain spotted fever -- lives parasitically in ticks and is transmitted by bite to vertebrate hosts.

Symptoms and Types

Certain breeds are more likely to develop a severe reaction to the R. rickettsii organism than others; these include purebred dogs and German shepherds. The signs and symptoms of Rocky Mountain spotted fever vary according to the type of disease the dog has. Most dogs will develop a fever within five days of contracting Rickettsia rickettsii. Other symptoms include:

• Depression
• Lethargy
• Anorexia
• Blood in the urine
• Irregular heart beat (arrhythmia)
• Discolored spots along the skin, often bruised or purplish in color
• Inability to walk normally, loss of coordination (ataxia)
• Swelling or edema (fluid retention) in the limbs
• Bleeding that occurs suddenly, most often from the nose, or in the stools
• Difficulty with blood clotting, which can lead to shock or death
• Swollen lymph nodes
• Pain in the eyes
• Inflammation, hemorrhage, or conjunctivitis in the mucosal membranes, most commonly in the eyes

Causes

Tick-borne rickettsial disease is caused by the R. rickettsii microorganism. The organism is carried by ticks and transmitted through bite to a host animal. Most infections occur in the months from March through October.

Diagnosis

You will need to give a thorough history of your pet's health, including a background history of symptoms, recent activities, and possible incidents that might have precipitated this condition. The history you provide may give your veterinarian clues as to which organs are being affected (e.g., heart, kidney).

Your veterinarian will make the diagnosis based on blood tests and skin biopsies from the affected areas, along with the symptoms that are presented. A heightened antibody count will show that an infection is present. Special stains can be used in a laboratory setting to confirm a diagnosis.