The severity of anaemia typically refers to how low the HCT/PCV has dropped below the reference range but there is no set “grading”r. The challenge is that proportionate drops in HCT/PCV do not relate to clinical conditions. While a severely anaemic animal is more likely to have clinical signs than one with mild anaemia, speed of onset and concurrent disease processes (infection, inflammation, organ damage) will also play a large part in the signs that we see. As a result, there is not a linear relationship between the severity of HCT/PCV reduction and clinical condition.