Babesia in Dogs Causes Babesiosis, the Most Common Tick-Borne Disease

Babesia in dogs causes Babesiosis.  Babesiosis is thought to be one of the most common tick-borne disease?

It’s only February and already people are finding ticks on their dogs and I even found one on me yesterday evening.  We need to be on the lookout for these tiny hitch hikers for they carry a number of infectious diseases: Lyme disease, Erlichiosis, Rocky Mountain Spotted Fever, and a not so well known infection, Babesiosis.

Babesiosis, caused by parasites of the genus Babesia, is one of the most common infections of free living animals world-wide and some species are gaining increasing interest as emerging zoonotic infections in humans.  These parasites require both a vertebrate and a non-vertebrate host to maintain their life cycles.  All babesial parasites are transmitted by ixodid ticks, the same tick that transmits Lyme disease.  In the vertebrate host the parasites replicate in the red blood cells and are called piroplasms due to their shape when within the infected host cells.


babesia in dogs
Canine blood smear of Babesia canis showing paired large merozoites (pair tear-drop forms). ……………………………………..NAVC Clinician’s Brief / July 2012 / Consultant on Call

Babesia in dogs or Canine babesiosis is an important disease world-wide and is not believed to be zoonotic. Historically, canine Babesia species  have been divided into two categories—large and small—based on the form found within the red blood cells.  Babesia canis is considered to be the most widespread and the most pathogenic.



Small Babesia species

  •  B gibsoni: worldwide
  • B conradae: southern California only
  • B microti-like (B annae, Theileria annae): Spain; also, prevalent in North American foxes; a single case reported in a dog (Mississippi)

Large Babesia species

  •  B canis vogeli: worldwide
  •  B canis canis: Europe
  •  B canis rossi: South Africa
  •  B coco: United States (in splenectomized
  • or immunosuppressed dogs)

Infection can occur in any canine breed and at any age.  There have been studies showing that B gibsoni infections are more prevalent in American pit bull terriers while B canis vogeli infections are more prevalent in greyhounds. Transmission to dogs primarily occurs through tick infestation, blood contamination, or a bite wound.  Remember, Babesia in dogs is very common so if your dog is bitten by another dog or has ticks, you want to be aware of symptoms.



  •  Tick infestation or exposure.
  • Recent dog bite (B gibsoni).
  • Blood transfusion from infected donor.
  • Splenectomy.
  • Immunosuppression.
  • Transplacental transmission.




Clinical signs can vary significantly because of differences among Babesia spp and individual patient response to infection. Clinical disease in dogs is variable and can be sublinical, chronic, or life threatening.

Typical symptoms are:

  • Lethargy.
  • Pale mucous membranes.
  • Generalized weakness
  • Bounding pulses.
  • Jaundice.
  • Vomiting (more commonly reported with B conradae infection).
  • Waxing and waning fever
  • Lymphadenopathy.
  • Splenomegaly.




Treatment choices largely depend on the Babesia species identified.

 Most dogs show response to treatment in 24–72 hours; however, it can take up to 7

days before results are apparent.  Hospitalization may be required, but many dogs can be treated as outpatients.  Infection that is not cleared may remain subclinical for life. Also, persistently infected dogs have potential for relapse, especially following splenectomy or if immunosuppressed.




Vector control is the primary means of preventing infection with tick-borne diseases.

In the case of Babesia transmission, proper infectious disease screening of donor before blood donation can prevent transmission via transfusion.  All animals should be screened before placement in a kennel or boarding facility.

Babesia in dogs is very common, but you help prevent it from occurring.

Mari Vogel received her Zoology Bachelor’s degree from the University of Montana, her Microbiology and Master of Science in Infectious Diseases from the University of London, and her Canine Massage Therapy Certification.

If you have any questions please contact Mari at 919-452-3467.


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