Myelodysplastic syndrome
anemia of chronic inflammation
Leukoerythroblastic anemia is caused by space-occupying lesions in the bone marrow that prevent normal production of blood cells. Increased destruction
Anemias of increased red blood cell destruction are generally classified as hemolytic anemias. These types generally feature jaundice, and elevated levels of lactate dehydrogenase. Intrinsic (intracorpuscular) abnormalities cause premature destruction. All of these, except paroxysmal nocturnal hemoglobinuria, are hereditary genetic disorders.Hereditary spherocytosis is a hereditary defect that results in defects in the RBC cell membrane, causing the erythrocytes to be sequestered and destroyed by the spleen. Hereditary elliptocytosis is another defect in membrane skeleton proteins. Abetalipoproteinemia, causing defects in membrane lipids
Enzyme deficiencies
Pyruvate kinase and hexokinase deficiencies, causing defect glycolysis
Glucose-6-phosphate dehydrogenase deficiency and glutathione synthetase deficiency, causing increased oxidative stress
Hemoglobinopathies
Sickle cell anemia
Hemoglobinopathies causing unstable hemoglobins
Paroxysmal nocturnal hemoglobinuria
Extrinsic (extracorpuscular) abnormalities
Antibody-mediated
Warm autoimmune hemolytic anemia is caused by autoimmune attack against red blood cells, primarily by IgG. It is the most common of the autoimmune hemolytic diseases. It can be idiopathic, that is, without any known cause, drug-associated or secondary to another disease such as systemic lupus erythematosus, or a malignancy, such as chronic lymphocytic leukemia. Cold agglutinin hemolytic anemia is primarily mediated by IgM. It can be idiopathic or result from an underlying condition.
Evidence for multiple causes appears with an elevated RBC distribution width (RDW), indicating a wider-than-normal range of red cell sizes, also seen in common nutritional anemia. Heinz body anemia
Heinz bodies form in the cytoplasm of RBCs and appear as small dark dots under the microscope. In animals, Heinz body anemia has many causes. It may be drug-induced, for example in cats and dogs by acetaminophen (paracetamol), or may be caused by eating various plants or other substances:

In cats and dogs after eating either raw or cooked plants from the genus Allium, for example, onions or garlic. In dogs after ingestion of zinc, for example, after eating U.S. pennies minted after 1982. In horses which eat dry or wilted red maple leaves. Hyperanemia
Hyperanemia is a severe form of anemia, in which the hematocrit is below 10%. Refractory anemia
Refractory anemia, an anemia which does not respond to treatment, is often seen secondary to myelodysplastic syndromes. Iron deficiency anemia may also be refractory as a manifestation of gastrointestinal problems which disrupt iron absorption or cause occult bleeding. Transfusion dependent
Transfusion dependent anemia is a form of anemia where ongoing blood transfusion are required. Most people with myelodysplastic syndrome develop this state at some point in time. Beta thalassemia may also result in transfusion dependence. Concerns from repeated blood transfusions include iron overload. This iron overload may require chelation therapy. Treatment
Treatment for anemia depends on cause and severity. Vitamin supplements given orally (folic acid or vitamin B12) or intramuscularly (vitamin B12) will replace specific deficiencies.