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Pet Owner Version

Ehrlichiosis and Related Infections in Cats


Jennifer H. McQuiston

, DVM, MS, Rickettsial Zoonoses Branch, Centers for Disease Control and Prevention

Reviewed/Revised Aug 2018 | Modified Oct 2022

Monocytic ehrlichiosis is caused by rickettsia organisms (a specialized type of bacteria that live only inside other cells). In dogs, the disease is usually caused by Ehrlichia canis, although other types of rickettsia are sometimes involved. A similar disease has been occasionally identified in cats in Africa, France, and the United States; however, the exact species causing the infection has not been determined. The disease is transmitted by ticks that become infected after feeding on infected animals.

Signs of ehrlichiosis commonly progress from short- to longterm. In short-term cases, signs can appear similar to other types of infections (such as fever, swelling of the lymph nodes, loss of appetite, depression, lethargy). In longterm cases, signs become more severe as white blood cells move into internal organs and the bone marrow produces fewer blood cells. Decreased numbers of platelets (which are critical for proper blood clotting) in the bloodstream is common in animals with all stages of ehrlichiosis. As the disease progresses, the severely low platelet level can cause an animal to bleed abnormally, resulting in bruises on the skin and gums, blood in the urine or stool, or spontaneous bleeding from the nose.

Laboratory blood tests are performed to diagnose these infections. For treatment, your veterinarian will prescribe an antibiotic. The medication is usually given for 10 to 21 days.

The most important preventive steps are those that control ticks, the most common source of the disease. If possible, keep your cat away from areas known to harbor ticks. Preventive medications that will keep your cat from being infested with ticks are also available. However, some products that prevent ticks on dogs can be dangerous for cats. Your veterinarian can recommend an appropriate product. Any ticks found on your cat should be promptly and properly removed to prevent the spread of disease. Remove any ticks by using fine-pointed tweezers to grasp the head of the tick (right where it enters the skin). Pull the tick straight off, making sure not to grasp or squeeze its body. If there are multiple ticks, it may be best to have your veterinarian remove them and examine your cat.

Some types of Ehrlichia bacteria can be transmitted to people. Despite the occurrence of disease in both animals and people, a tick is required for transmission, so cats and other infected animals do not pose a direct transmission risk in normal circumstances. Infection in animals may indicate a heightened risk of human infections related to tick exposure in a given area.

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