Assessment of biotin deficiency in animals.

Biotin deficiency can be induced readily in monogastric animals and is accompanied by characteristic abnormalities. These include dermal lesions involving hyper- and parakeratosis and, in fur-bearing animals, alopecia and achromatricia. Biochemical changes include depressions in the activities of biotin-dependent enzymes and the metabolic pathways in which they are involved. However, it has been shown in chickens that the relative changes in the activities of these enzymes and the resultant manifestations of the deficiency can be markedly influenced by the dietary content of other nutrients such as protein or fat. Biochemical criteria are required for the diagnosis of subclinical deficiency and these are best-established for poultry. Blood pyruvate carboxylase activity is a good criterion in young birds. Biotin-responsive disorders have been identified in several species. The etiology of fatty liver and kidney syndrome in chickens is now largely understood and is an interesting example of how a combination of nutritional and environmental factors can result in sudden death in, until then, apparently healthy animals.