Malnutrition occurs when the diet fails to provide adequate energy and protein to meet needs for growth and maintenance of body weight. It predisposes to other conditions such as plant poisonings in drought and pregnancy toxaemia.
In some cases the diet may be adequate and other conditions may reduce appetite (see inanition) or interfere with normal digestion and absorption (parasitism) or increase metabolic rate and feed requirements (inflammation). Diets may also be deficient or unbalanced in particular elements such as energy, protein, minerals and vitamins.
Growth or weight gain may be diminished, especially in young animals. Inappetence, weight loss, pale mucous membranes indicating anaemia and swelled head due to fluid accumulation under the skin may be observed.
Diagnosis is generally by clinical examination and necropsy of affected animals to determine if underlying disease is present. Generally, fat depots will be reduced and wet or absent (serous atrophy), tissues will be pale (anaemia) and free fluid will be present in abdomen (ascites), chest and heart sac (pericardium).
Differential diagnoses include parasitism, infectious diseases such as pneumonia and Johne's disease, chronic conditions causing organ dysfunction such as pyrrolizidine alkaloidosis and arthritis, and deficiencies of copper, selenium or cobalt. A full range of fresh and formalin fixed tissues plus faeces, serum and plasma may be needed for laboratory differentiation.
Review the composition of diet and make any necessary corrections. Treatment of chronic conditions is unlikely to be economically justified.
Prevention of malnutrition requires provision of adequate dietary energy and protein and resolving any underlying health problems.