Tick-borne diseases in dogs: Babesiosis

Author: Luana Battaglia, Ilona Judhianto and Stefanie Stobbe | Read time: 9 min

Babesiosis is a disease transmitted mainly by the bite of ticks infected with the protozoal parasites Babesia spp. Within the bloodstream, babesia damages red blood cells, causing progressive anemia.

Babesiosis occurs in various domestic animals (dogs, cats, horses, pigs, cattle, sheep and goats) and wildlife, and can also affect humans. In pets, babesiosis is much more common in dogs, with cats reported mainly in southern Africa. However, there are several different species of both Babesia and ticks, which makes the disease significant worldwide. Babesiosis’ geographical distribution has shifted over the years due to climate and ecosystem changes, altering the concept that contamination is limited to certain areas and tropical countries.

Signs and symptoms

Clinical signs of babesiosis in dogs can be seen within 24 hours of the tick bite, but usually take 2-3 weeks to appear. The most common are listed below:

• Lethargie, Appetitlosigkeit
• Pale gums (indicating anemia)
• Fever (may not be present initially)
• Jaundice, and dark-colored urine (dark yellow or reddish)

Babesiosis can still progress silently and slowly for months (chronic form), with periods of improvement and worsening, without the symptoms being noticed.
Unfortunately, the disease can get worse at any time and put your pet’s life at risk. It is therefore important that you take your pet to the vet if you notice that something is wrong.

Diagnosis

The diagnosis can be challenging and is made based on a detailed history, physical examination and blood tests. For example, it is important to tell the veterinarian if your dog stems from another country or if you have traveled with it, its vaccination status and whether you used products to prevent ticks.

During the physical examination, the vet may be able to notice abnormalities such as enlarged lymph nodes and spleen. General blood tests such as a complete blood count and biochemical panel may detect anemia and low platelet counts, as well as elevated bilirubin and low total protein levels. Urine tests may be helpful in confirming the suspected diagnosis. There are three specific blood tests to try to diagnose the parasites:

Microscopy

A blood smear is prepared and analyzed under a microscope so that babesia can be observed within the red blood cells. If they are found, the diagnosis is definite. However, microscopy is considered a low sensitivity method as the parasites use to hide in specific organs during the course of the disease and thus cannot always be seen in the blood. The identification itself can also be tricky, so an experienced pathologist is key to reliable results!

Serology

A blood sample is used to identify antibodies against babesia in the individual’s body. There are two serology tests currently available: indirect fluorescent antibody (IFA) and enzyme-linked immunosorbent assay (ELISA).

Unfortunately, some infected animals may not have detectable antibodies or show them late in the infection, leading to a false negative test result. Other animals may still have antibodies for years after they have recovered from the disease, giving a false positive result.

Nucleic acid detection

This method allows the DNA of the babesia to be extracted and amplified from the infected red blood cells of the dog. A positive result confirms the infection and also identifies the babesia species, which is important for treatment and prognosis. However, a false negative result can occur if the parasites are not present in the blood when the sample is taken.

As you can see, no test is perfect for diagnosing Babesiosis. All methods have limitations and can give either false positive or false negative results. It is therefore necessary to combine different tests and compare them with the results of the clinical examination and the individual’s symptoms. Only well-trained and up-to-date professionals, such as ourselves at Tierarztpraxis Bärenwiese, can correctly assess all the information provided and determine the best treatment for
your pet.

Treatment

Treatment is based on the use of an antiprotozoal medication given orally or by injection sometimes in combination with oral antibiotics. In some very specific cases, the use of immunosuppressive drugs may be indicated.

The timing and regime of treatment depend on many factors including the possibility to identify the Babesia species, the drugs available, the animal’s immunity and the individual’s response to the medication.

Most dogs show a marked improvement of symptoms within 24 to 72 hours of starting treatment. It is worth noting that if your dog is very weak, hospitalization for supportive care or even a blood transfusion may be necessary.

Prognosis

The prognosis for the disappearance of symptoms is usually good, depending on the babesia species, the general health of the animal at the time of diagnosis and its response to treatment. However, dogs infected with small babesia species that recover from the disease are often not cured. They remain infected and may suffer relapses throughout their lives. In this way, they can therefore also act as a source of infection for previously uninfected ticks or for other dogs that come into direct contact with their blood.

Control and Prevention

The most effective way to prevent babesiosis is to keep your dog tick-free. There are a number of ways to do this such as pills, spot-on products or anti-tick collars. However, the products alone may not be enough to prevent babesiosis if the environment is heavily infested with ticks, which may happen for example in woodlands. It is therefore recommended that you only walk your dog in well-maintained grassy parks. When returning home, check with the help of a fine-toothed comb if there are any ticks on your pet. Fortunately the transmission of tick-borne diseases is often not immediate, so prompt removal can considerably reduce the risk of infection. In addition, proper tick removal will prevent itching and inflammation at the site of the bite.

If you are planning to bring a dog into your home from an area where babesiosis is endemic, it is highly recommended that the dog is examined by a vet, and tested and quarantined before being introduced to other dogs.
There are currently no commercially available vaccines against babesiosis available in Germany.

Zoonoses

Cases of human babesiosis have been reported but the babesia species found in dogs and cats do not seem to infect immunocompetent humans. According to Phillip D. Carter and Peter Rolls (www.msdvetmanual.com/circulatory-system/blood-parasites/babesiosis-in-animals), “the rodent parasite B microti and the cattle parasite B divergens are the most commonly implicated species in North America and Europe, respectively. However, B duncani, B venatorum, and some less well-defined species have also been implicated. The reservoir hosts and vectors of some of these species are not necessarily known. Babesiosis infections in humans are 
infected ticks or via contaminated blood from an infected transfusion donor”.

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