Dogs become infected with babesiosis after being bitten by ticks carrying a blood parasite called Babesia. The severity of the illness varies depending on the species of Babesia involved as well as the immune response of the infected dog. The primary manifestation of a babesiosis infection is anemia due to the destruction of a dog's red blood cells. Untreated, babesiosis can be fatal.
What Is Babesiosis?
Babesiosis is a blood-borne infection caused by Babesia, a genus of protozoa that comprises over 100 species of infectious parasites. The many strains of Babesia infect a variety of animals, but there are only a few strains that target dogs. Babesiosis results in the destruction of a dog's red blood cells, organ damage, and potentially even death.
Symptoms of Babesiosis in Dogs
Babesiosis infections vary in severity, from mild to life-threatening. Babesia strains in the U.S. generally produce milder disease compared to those found in other countries, but serious symptoms can occur.
Fever and swollen lymph nodes indicate an immune response to help fight the infection, but the primary symptoms of babesiosis are indications of red blood cell destruction within the dog's circulatory system. Diminished red blood cells cause anemia, which presents as paleness of the skin and mucous membranes as well as dark-colored urine.
In severe cases of babesiosis, multiple organ systems are affected, including the lungs, gastrointestinal tract, kidneys, nervous system, spleen, and liver. Jaundice is an indication of impaired liver function.
The course of this disease may be cyclical, especially in the milder forms, with symptomatic and asymptomatic episodes.
Causes of Babesiosis
Babesiosis is almost exclusively a tick-borne disease. Rarer causes of babesiosis may include:
- Blood transfusions
- Bite wounds from dogs infected with Babesia gibsoni
- Maternal transmission to pups via the placenta before birth
Diagnosing Babesiosis in Dogs
It can be difficult to confirm a diagnosis of babesiosis. Blood tests may show a decrease in the number of red blood cells and platelets (thrombocytopenia), but this is not specific to Babesia. Blood smears can be examined for the presence of the Babesia organisms. If they are present, the diagnosis can be confirmed, but they may not always show up on a smear. Taking blood from a cut on the ear tip or from a toenail can improve the odds of finding the parasites.
Blood can also be tested for antibodies to Babesia, though this can sometimes produce misleading results. Specialized testing can check for genetic material from Babesia, and while this is the most sensitive test, it is not widely available.
The diagnosis is further complicated by the fact that dogs infected with babesiosis may also be infected with other diseases carried by ticks, such as ehrlichiosis, Lyme disease, or Rocky Mountain spotted fever.
Generally, a combination of lab tests along with clinical signs and history are used to make a diagnosis.
A variety of drugs have been used to treat babesiosis with varied success. Imidocarb dipropionate and diminazene aceturate are options that have potentially severe side effects. A newer combination of drugs including azithromycin and atovaquone is promising, though expensive. In severe cases, blood transfusions may be necessary.
Prognosis for Dogs with Babesiosis
Treatment relieves the symptoms of babesiosis, but it does not fully clear the parasite from the body. Dogs that recover initially may remain infected at a low level and can experience symptomatic flares in times of stress or reduced immune function.
Dogs with sudden, severe infections or those that are not treated promptly when they begin showing symptoms can experience organ failure and die.
How to Prevent Babesiosis
Preventing exposure to the ticks that carry Babesia is the best means of preventing babesiosis. Check your dog daily for ticks and remove them as soon as possible (ticks must feed for at least 24 to 48 hours to transmit Babesia). This is especially important during peak tick season (April through October). Keeping your dog out of wooded or tall grass areas will also help limit exposure to ticks.
Products that prevent ticks such as monthly parasite preventatives, tick collars, or yard/kennel treatments can be used to deter ticks, but serious side effects are possible in some dogs.
A babesiosis vaccine is available in Europe, but is only effective against particular strains of Babesia and is not 100 percent effective.
Is Babesiosis Contagious to Other Animals?
There are rare cases of babesiosis transmission between dogs from bite wounds or mother-to-pups prenatally. These incidents are not nearly as likely as transmission from ticks.
Babesiosis. Merck Veterinary Manual.
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