Blood Test Values

the results of my puppy blood test showed a little low red and white blood cells. It weighs only 2.5 pounds and the vet said that these values could be his "normal." She said it's not accurate to compare its results with results of a 50 lb. dog.

Is this true? I thought "normal" numbers in results of blood tests have been this way, regardless of the size of the animal or breed.

They will check her again in a few weeks to be sure. She did not act sick at all, but it does not eat much, even if the effect of red blood cells?

Should I be worried?
What is the worst bit low red and white blood cells could indicate? Cancer? Parvo (she is vaccinated)? Anything else?

normal for an animal is not normal for the next blood work moves from a normal range. that for the range of normal dogs for red cells is 5.6 to 8.7
http://www.peteducation.com/article.cfm? ...
for now there is not much to worry about.