These infections occur by transmission of the protozoal parasites called Babesia. They attack red blood cells and so a common symptom of Babesia is anemia. Infection however isn't limited to the blood and can attack other parts of the body and the severity of symptoms/illness will vary from species to species of Babesia.
There are many species of babesia, and each infect its own separate host species, but there are a few that can infect dogs. Though the most common mode of transmission is through ticks (making this infection more common in warmer climate) there are certain Babesia species that can be transmitted through blood transfussions, bite wounds, and mother to pup.
Any dog can contract the protozoan but young dogs tend to get especially sick. Greyhounds, Pitbull Terriers, and American Staffordshire Terriers seem to be breeds that are most susceptible to the illness.
Symptoms:As said before, the severity of this will depend on the species of Babesia and also on the immunity of the dog. Some cases may not even show clinical signs and the more severe cases may end up in fatalities.
Symptoms include:
•fever
•weakness
•lethargy
•pale gums and tongue
•red or orange urine
•yellow tinge to skin, gums, whites of eyes, etc
•enlarged lymph nodes
•enlarged spleen
DiagnosisDiagnosing this disease can prove to be difficult even though there are multiple ways to do so, not one is fool proof.
-WBC/ Platelet count: Taking a count of white blood cells and platelets is an indication of Babesiosis but isn't really specific to it.
-Blood Smears: If the parasite is present in the blood smears then the vet can diagnose it as such, but the parasite may not always show up in these tests.
-Checking for antibodies: A vet can check to see if the dog has antibodies for Babesia but these results may give misleading results
-Checking for DNA: Tests can be given to see if any genetic material from Babesia can be found. While this may be the most sensitive test, its not widely available.
Complicating diagnosis of Babesiosis is that the dog may be carrying other illnesses that are generally transmitted by ticks.
Prevention:Since tick transmission is the most common way to contract the disease the best way to prevent it is to make sure your dog doesn't have ticks on it. If you are in warmer climates and if your dog spends lots of time in tall grasses its always a good idea to check for ticks. The tick would have to feed for a period of 1-2 days before it spreads Babesia.
(Summary from
http://vetmedicine.about.com/od/diseasesandconditions/a/CW-Babesia.htm?nl=1 )