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Introduction:
When the tissue concentration of a nutrient falls to
a critical level, evidence of deranged cellular metabolism occurs, and
abnormal metabolites appear ion blood, urine and faeces. As the deficiency
progresses, microscopic tissue changes develop in rapidly metabolising
tissues such as skeletal muscle, myocardium and brain.
Immature animals are the most susceptible to nutritional
disease, and the rapidly growing tissues such as bone are also markedly
affected.
The time taken for nutritional disease to develop will
influences the course and character of the tissue changes. Lesions of
acute deficiency and chronic deficiency are often different. Pigs with
acute thiamine deficiency may die suddenly of cardiac failure with few
lesions in cardiac muscle, whereas those with chronic deficiency have
severe lesions in the heart.
Multiple deficiency is the usual case in animals: that
is, a diet of poor quality is most likely lacking in several poor quality
nutrients. When a deficiency of several essential factors occurs, syndromes
develop that are different from the combined effects of the individual
deficiencies.
Nutritional imbalance is more common than a simple deficiency
of one particular dietary factor. Some of the delicate interrelationships
in nutrition are those of calcium & phosphorous, fat & calcium,
and iron & phosphorous. Excess of one dietary component may enhance
the deficit of another.
 
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Veterinary Pathology - Nutritional Pathology