It is defined as decrease in the amount of haemoglobin (Hb) per unit of blood. This may or may not be accompanied by a reduction in the red blood cells (RBCs). A decrease in the quantity of Hb limits the oxygen supply to various tissues. Anaemia itself is not a disease but a sign of disturbance in the haemopoietic system.
Etiology: It may be classified as haemorrhagic anaemia, haemolytic anaemia, and nutritional anaemia. Haemorrhagic anaemia is caused by abomasal ulcer, bovine enzootic haematuria, pyelonephritis, castration, dehorning, traumatic pericarditis, liverfluke infestation, nasal bleeding, rupture of spleen or liver, heavy infestation of blood sucking worms, lice or ticks, and traumatic injury to a blood vessel. Haemolytic anaemia is caused by babesiosis, anaplasmosis, theileriosis, trypanosomiasis, bacillary haemoglobinuria, leptospirosis, post-parturient haemoglobinuria, drinking of cold water by calves, transfusion reaction, copper poisoning, haemoglobinuria in snake bite and phenothiazine poisoning. Nutritional anaemia occurs owing to deficiency of copper, cobalt, iron, niacin, riboflavin, pantothenic acid, pyridoxine and choline.
Anaemia can also be classified on the basis of morphology as microcytic normochromic, microcytic hypochromic, normocytic normochromic, normocytic hypochromic, macrocytic normochromic and macrocytic hypochromic.
Clinical signs: Most important clinical sign is pallor mucous membranes. There is muscular weakness, depression, inappetance, weak pulse, dyspnoea and increase in heart rate and intensity of heart sounds, edema, jaundice or haemoglobinuria.
Diagnosis: Faecal examination may be done to exclude gastrointestinal parasites. Blood smear is prepared to look for parasites. Morphology of red blood cells is important. PCV, Hb, RBC, MCH, MCHC and MCV may be estimated to know the nature of anaemia. Reduced total plasma protein gives a clue for haemorrhagic anaemia.
Treatment: T he primary cause of anemia should be treated for effective management. Blood transfusion is recommended in acute haemorrhage. Haematinic therapy such as iron dextran injections or iron, copper and cobalt mixture orally, should be given for blood cell formation.