Babesiosis (Piroplasmosis) in Dogs

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4 min read

Key takeaways

Babesiosis is a blood infection caused by Babesia spp. parasites. There are over 100 species globally and cases occur across North America.

  • Babesiosis is usually transmitted by ticks
  • It may also be spread during dog fights or across the placenta
  • Infected dogs display fever, loss of appetite, weakness, and lethargy
  • More severe cases may show additional symptoms with complications like liver and kidney disease or central nervous system damage
  • Babesia parasites are often identified during microscopic analysis of blood cells during routine testing, and PCR tests identify the specific species
  • Babesiosis is treated with antimalarial and antibiotic medications, along with blood transfusion and supportive therapy when required
  • Prognosis for infected dogs varies with severity
  • Babesiosis is a contagious blood-borne pathogen which may be transmissible from animals to humans
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A closer look: Babesiosis (Piroplasmosis) in Dogs

Babesiosis is the second most common type of blood parasite in dogs. There are over 100 species of Babesia spp. worldwide, although only a small percentage of species can infect canines or humans. Different species of Babesia are found across North America. Sometimes the red blood cell damage caused by babesiosis is severe enough to lead to liver disease, kidney disease, and central nervous system disease complications.

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Risk factors

Factors that increase the risk of exposure to babesiosis include:

  • Tick exposure
  • Inter-canine fighting
  • Kennel housing

Certain dog breeds show a high incidence of infection, including pit bull terriers and greyhounds. Uncommonly, humans are infected by blood transmission. Only those who are immunocompromised or have had their spleen removed have cause for concern.

Possible causes

Babesiosis is caused by infection with a blood parasite called Babesia sp.

Babesia parasitees can be transmitted through:

  • Tick bites
  • Direct blood transmission, especially during dog fights
  • Transplacentally

Main symptoms

The immune system recognizes and attacks the infected blood cells, and in many cases also attacks the healthy blood cells. This happens faster than the cells can regenerate, developing into a condition called immune mediated hemolytic anemia.

The symptoms of Babesiosis are primarily the result of anemia (a low red blood cell count) and hemolysis (red blood cell damage).

Many cases of babesiosis are asymptomatic.

Testing and diagnosis

Common diagnostics used to identify babesiosis are:

  • Blood tests
  • PCR tests
  • Fluorescent antibody test

By itself, serology is an unreliable method of diagnosis, as the results can produce false positives or negatives. Definitive diagnosis relies on identifying the parasites on a blood smear or through a PCR test which also identifies the specific species of Babesia.

With cases where babesiosis is strongly suspected, it is recommended to begin treatment while awaiting a specific diagnosis.

Steps to Recovery

Babesiosis is treated using antimalarial medication and antibiotics. Blood transfusions and fluid therapy are sometimes necessary to recover healthy blood cell levels. With treatment, dogs are expected to recover within a few weeks. Recovered dogs are still considered at risk of relapse and may still transmit infection to other dogs. The prognosis is dependent on severity and which systems are affected by the infection.


Babesiosis spreads primarily through tick bites or blood contact.

The most effective method to prevent infection is through tick control, as well as avoiding exposure to inter-dog aggression and canine racetracks.

Is Babesiosis (Piroplasmosis) in Dogs common?

Babesiosis is common in dogs.

Typical Treatment

  • Antimalarial medication
  • Antibiotics
  • Blood transfusion
  • Supportive therapy


Adam J Birkenheuer 1, Maria T Correa, Michael G Levy, Edward B Breitschwerdt - Writing for Journal of the American Veterinary Medical Association
Wendy Brooks, DVM, DABVP - Writing for Veterinary Partner
Remo Lobetti, BVSc, MMedVet (Med), DECVIM (Internal Medicine) - Writing for Veterinary Partner
Malcolm Weir, DVM, MSc, MPH; Ryan Llera, BSc, DVM; Ernest Ward, DVM - Writing for VCA Animal Hospitals
Barri J. Morrison, DVM - Writing for PetMD

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