Iron deficiency

Iron plays an essential role in oxygen transport in the body as a constituent of haemoglobin where nearly 60% of the body iron is found. Apart from oxygen transport from the lungs to tissue, iron is vital for oxidative mechanism of the cell, and participates in electron transport chain being a part of cytochrome oxidatase enzyme. Deficiency of iron is not very common in farm animals, except in young animals. It is characterized by anaemia and associated signs.

Aetiology: In animals, iron deficiency is usually primary.  Generally, newborn animals are given sole milk diet, which is a poor source of iron. As the hepatic iron store in newborn is not enough to maintain normal haemopoiesis for more than 2-3  weeks, the newborns, particularly piglets suffer more frequently to iron deficiency.Lack of access to soil to growing piglets and housed lambs is also suggested as contributory factor causing iron deficiency. Subclinical anaemia and iron deficiency may be associated with continued blood loss due to haemorrhages. Cattle heavily infested with ectoparasites may even develop fatal anaemia. Sub-normal iron- responsive haemoglobin level has been reported in horses harbouring heavy infestation of strongylid worms. Conditioned iron deficiency may develop due to addition of calcium carbonate in the diet of weaned and finishing pigs.

Clinical findings: Progressive development of hypochromic-microcytic anaemia is the characteristic finding in iron deficiency. Piglets at about 3 weeks of age have the highest incidence of iron deficiency anaemia. The growth rate and feed intake of the affected pigs are significantly reduced. Signs of dyspnoea, lethargy, pale skin and mucosa, oedema of the head and fore quarters and diarrhoea are seen.Affected animals may die suddenly or may survive in a thin, unthrifty condition. High incidence of infectious diseases such as E. coli and streptococcal pericarditis is associated with anaemia. Iron deficiency also increases severity of Trichuris suis and Ascaris suum infections in pigs. Iron deficiency in calves, lambs and kids is also associated with signs of anaemia. Calves also show atrophy of lingual papillae.

Diagnosis: Response to iron therapy indicates iron deficiency. Determination of haemoglobin, packed cell volume and red blood cell count is used to identify anaemia. Normal haemoglobin values in pigs, cattle, sheep and goats are 100-160 g/l, 80-150 g/ l, 90-150 g/l and 80-120 g/l. Erythrocyte count also decreases in iron deficiency and may be a better indicator of iron status than haemoglobin values. The haemoglobin level of 40 g/l and erythrocyte count of 3-4 x 1012/l indicate iron deficiency anaemia in piglets. Serum ferritin concentration is used for monitoring pre-latent iron deficiency in calves.

Treatment and prevention: Treatment includes parenteral administration of organic iron preparations such as iron dextran, iron sorbitol citric acid complex or iron gluconate. Weekly intramuscular administration of iron preparation (100-200 mg for piglets, 300 mg iron dextran for lambs and 0.5-1 g elemental iron for horses) can be used. Vitamin B12 is also used along with iron preparations.Iron deficiency anaemia can be prevented by oral or intramuscular administration of a commercial grade iron to piglets @ 15 mg daily until wearing. A diet supplemented with 2 g iron per kg DM to sow is effective in preventing anaemia is piglets.  Calves should be provided iron supplementation in milk replacer @ 1 g – 2 g per kg DM. Intramuscular injection of 300 mg iron dextran at 24 hour age is an effective measure to prevent iron deficiency in housed lambs.