Anemia according to etiology and pathophysiologic condition:

1. Haemorrhagic anemia:

• There is loss of RBCs in this type of anemia. Blood loss exceeds production.
• It occurs when 25-40% of blood is lost. This condition leads to hypochromic, microcytic anemia
• It may be acute or chronic in nature
• Acute haemorrhagic anemia occurs due to:
  • Any wound
  • Epistaxis
  • Hemoptysis
  • Surgical bleeding
  • Splenomegaly in dog
  • Brackern fern poisoning
  • Sweet clover poisoning
  • Rapid X-ray exposure
  • Gastrointestinal hemorrhage
  • Genito-urinary hemorrhage
• Chronic hemorrhagic anemia occurs due to:
  • Heavy ectoparasitic infestation
  • Endoparasitic infection
  • Deficiency of vit. K, vit.C and prothrombin
  • Coccidiosis in young animals
  • Enzootic bovine Hematuria

2. Hemolytic anemia:

• This type of anemia occurs due to accelerated erythrocyte destruction.
• It is characterized by macrocytic hypochromic anemia.
• It may be of 2 types; congenital hemolytic anemia and acquired hemolytic anemia
• Congenital anemia occurs due to defect in formation of stroma of protein or hemoglobin. It is heritable disease due to simple Mendelian recessive gene.
• Acquired hemolytic anemia occurs due to:
  • Viral infection: Equine infectious anemia, infectious mononucleosis
  • Bacterial infection: Leptospirosis, Clostridium haemolyticum, Clostridium perfringens type A, streptococcal and staphylococcal infection
  • Protozoal infection: Babesiosis in all species, Anaplasmosis in ruminants, theileriosis, haemobartonellosis in dog and cat
  • Phosphorus deficiency
  • Copper poisoning
  • Phenothiazine toxicity
  • Ingestion of arsenic, bismuth, lead
  • Excessive use of sulphonamides and other aspirin drug
  • Snake venom

3. Immunological haemolytic anemia:

• It is of 2 types; Autoimmune haemolytic anaemia and iso-immune haemolytic anemia
• Auto-immune hemolytic anemia:
  • It is recorded in dog and cat
  • Under special circumstances, there may be mutation of genes and protein of own body becomes antigen and body produced antibody against own erythrocytes.
  • Due to result of Ag-Ab reaction, hemolysis occurs
  • Disease is characterized by sudden onset of anemia and spherocytosis
• Iso-immune haemolytic anemia:
  • This anemia occurs due to transfer of maternal iso-antibodies from dam to new-born through colostrum.

4. Dyshaemopoetic anemia:

• This anemia results due to depression of erythropoiesis
• Certain chronic suppurative process may depress bone marrow activity leading to less production of erythrocytes.
• It may be observed in case of nephritis, chronic interstitial nephritis, neoplastic disease, rapid exposure to X-ray or other radioactive substances, drug toxicity, viral infection causing marrow suppression.