What is the time frame of infection?
The usual incubation period is 21 to 28 days.  During the first 21 days the red blood cells are being infected and the bodies filter system picks out the infected red blood cells and destroys the cells.  The cow is able to make red blood cells as fast as they are being destroyed early in the disease process.  At about the 21 day the infection goes into a logarithmic stage and red blood cells become infected in mass numbers.  These infected red blood cells will be removed from circulation and destroyed

When will I know the cow is infected?
Bovine show no clinical signs of anemia until 50% of their Red Blood Cells (RBC) have been destroyed.  In Acute Anaplasmosis by the time clinical signs of anemia occur, 40% to 60% of their remaining RBC’s are infected and going to be destroyed.

Below is an example of daily RBC loss in an acute case.  Each vial represents a 24 period.

Why is the vaccine so expensive?

Because it works!  You could vaccinate a herd of 100 for about the same cost of losing one cow, depending on stockyard prices.

Is there a withdrawl period with the vaccine?

Yes, 60 days.