A. Anemia is not a common sequela to diabetes. There is something else unrelated going on here. Anemia is either caused by immune mediated hemolytic anemia (IMHA), losing blood internally (will have low TotalProtein (TP) also on bloodwork if this was the case), or more rarely a bone marrow problem where not enough red blood cells are being made.
Your veterinarian should be able to pinpoint which is more likely based on bloodwork results and he/she should be able to make recommendations for either more testing to confirm or a treatment to correct the anemia.
I will say that your pet is older and a Rottweiler, in which case bone cancer is a probability here and would be harder to diagnose with just bloodwork, more extensive testing such as radiographs and potentially a bone marrow biopsy would be needed.
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