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Confidently identify parasites on blood smears
Blood film evaluation skills a little rusty when it comes to hemoparasites? Have no fear. Read on for tips to help you prepare a readable blood smear and identify what you see.


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Babesia species

Facts

• Nine species have been identified in dogs, but Babesia gibsoni and Babesia canis are currently the most common in the United States.

Babesia gibsoni and B. canis can both be transmitted through ticks and, rarely, blood transfusions; however, B. gibsoni can also be transmitted dog-to-dog via bites.

Babesia gibsoni is prevalent in pit bull populations, whereas B. canis is commonly identified in greyhounds.

Identification

• Piroplasms of Babesia species can be found within erythrocytes.

• Because of the increased weight of parasitized erythrocytes, they are often pushed to the feathered edge of the smear.

Babesia gibsoni inclusions appear as small, pleomorphic ring-shaped organisms (Figure 3).

Babesia canis inclusions are much larger than those of B. gibsoni. They are teardrop-shaped and often found in pairs (Figures 4A & 4B).


3. Babesia gibsoni on a blood smear. It can look similar to Cytauxzoon species (Figures 5A-5C), but B. gibsoni is exclusively seen in dogs, whereas Cytauxzoon species is exclusively seen in cats (Wright’s stain; 50x).

4A & 4B. Babesia canis on a blood smear. It is common to find multiple piroplasms within one red blood cell (Wright’s stain; 100x).














Clinical and laboratory signs

• Moderate to severe hemolytic anemia

• Thrombocytopenia

• Cyclic fever

• Hyperglobulinemia (seen as an elevated total protein concentration on a refractometer)

• Splenomegaly

Treatment

• Therapy is aimed at treating specific Babesia species, so correct identification is imperative.

Babesia gibsoni infection is treated with atovaquone (13.5 mg/kg orally three times a day) given with a fatty meal, plus azithromycin (10 mg/kg orally once a day) for 10 days.

Babesia canis infection is treated with imidocarb (6.6 mg/kg given subcutaneously or intramuscularly, repeated in two weeks). Premedicating with glycopyrrolate is suggested.

• Do not give prednisone until treatment of the parasitic infection is concluded.


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Source: FIRSTLINE,
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