EHRLICHIOSIS: A THREAT TO YOUR PET!

In my practice I have seen an increase of dogs that are testingpositive for a tick disease called Ehriichiosis. I found this very informative article by Dr. Mike Paul for the pet health network and wanted to share with my Pet talk readers.

[ note: This article covers E. canis which causes only one type of ehrlichiosis. E. ewingii and E. chaffeensis are different infections and create different clinical diseases.]

Ehrlichiosis is an emerging disease caused by a rickettsia: a type of bacteria that infects dogs, people, and less commonly cats. For dogs in North America and world-wide most cases of ehrlichiosis are caused by Ehrlichia canis (canine monocytotropic ehrlichiosis).1 Transmission is always from tick bites. Although people and dogs often live in close relationship to, and may come in contact with, the same species of tick, E. canis infections in people are thought to be rare.

E canis is most often transmitted by the brown dog tick (Rhipicephalus sanguineus). Infection likely requires several hours of tick attachment to the dog, and clinical signs may not appear for 1Ñ3 weeks or longer.

Stages of ehrlichiosis in dogs

There are 3 differing stages of the disease in dogs.

Acute phase of ehrlichiosis:Ê

¥ Clinical signs appear 1-3 weeks after exposure

¥ Fever, anorexia, lethargy

¥ Enlarged lymph nodes

¥ Thrombocytopenia (low platelet count) and bleeding tendency

Most dogs that are treated adequately recover at this point. Untreated dogs and some treated dogs may progress to the subacute and chronic phases.2

Subacute phase ehrlichiosis:

¥ Few, if any clinical signs

¥ Hypergammaglobulinemia (abnormally elevated immune proteins)

¥ Thrombocytopenia and anemia (low red cell count)

¥ This phase can last months to years

Chronic phase of ehrlichiosis:

¥ Lethargy, weight loss

¥ Reduction in red and white blood cell counts

¥ Bone marrow supression and bleeding

¥ Death

Less commonly, infected dogs can also exhibit inflammatory diseases of the eye and nervous system. The severity ofÊthe illness may be influenced by the disease strain, the dogÕs immune status, and the presence of co-infections with other tick-borne or flea-transmitted pathogens.

Progression to subacute and chronic disease may be attributed to an ineffective immune response on the part of the dog.

Diagnosing Ehrlichia in dogs

¥ A presumptive diagnosis may be made when clinical signs and a history of exposure to the tick vector lead to a high level of suspicion.

¥ Monocytes, a kind of white blood cell, can occasionally help with diagnosis.

¥ Confirmation may require using an anitbody test such as an ELISA that also looks for Anaplasma, Lyme disease, and heartworm infection. Polymerase chain reaction (PCR) to look for the organismÕs DNA footprint is also commonly available.

Treatment options for ehrlichiosis in dogs:

¥ DoxycyclineÊ

¥ Minocycline

¥ Tetracycline

Treatment should be maintained for at least 4 weeks.

Prevention of ehrlichiosis

There is no available vaccine and the best ways to prevent these infectious bites are with year-round tick repellents, thorough body checks after being outside, and proper removal of ticks. The Companion Animal Parasite Council recommends that all dogs be tested yearly for tick-borne diseases and that all dogs be treated with effective tick-control agents year-round. Comprehensive screening is important to find coinfections and to determine the success of prevention strategies.

If you have questions regarding this or other tick born diseases please contact Dr. Underwood at catdoc56@gmail.com