Anemia
- Anemia is defined as an absolute decrease in the red cell mass as measured by RBC count, hemoglobin concentr opation, and/or PCV.
- Clinically manifested by pale mucous membrane, tachycardia and loss of muscular strength and vigour.
- It can develop from
2.Destruction of Erythrocytes (Haemolysis)
3.Lack of production of Erythrocytes
Classification of Anemia
1. Regenerative Anemia
Regenerative anemias include bood loss anemia (hemorrhagic) and hemolytic anemia.
1.1 Hemorrhagic anemia
- Acute blood loss can lead to shock and even death if >30%–40% of blood is lost and the hypovolemia that develops is not treated aggressively with IV fluids or compatible blood or both.
- Causes of acute loss can be known (eg, trauma, surgery) or occult (eg, GI blood loss).
- Coagulopathies, bleeding tumors, gastric ulceration, and external or internal parasites should be excluded as causes.
- GI parasites, such as Haemonchus in ruminants and hookworms in dogs, can lead to severe blood loss, especially in young animals.
- Low-grade, chronic blood loss eventually results in iron-deficiency anemia, although some degree of reticulocytosis may persist even after iron stores become depleted.
- The hallmark of an iron-deficiency anemia is microcytic, hypochromic anemia.
- This chronic blood loss can be due to some type of parasitism in young animals (eg, fleas, lice, intestinal parasitism), but in older animals, bleeding from GI ulcers or tumors is more common.
- Hemolytic anemias are typically regenerative and result from lysis of RBCs in either the intra- or extravascular space.
- Intravascular hemolysis results in hemoglobinemia and hemoglobinuria, whereas extravascular hemolysis does not.
- Both types of hemolysis can result in icterus.
- In dogs, the most common cause of hemolytic anemia is immune mediated (60%–75%), although toxins, RBC trauma, infections, neoplasia, and RBC membrane defects can also cause hemolysis.