Vitamins are essential for metabolism, development of the immune system and amongst various other functions also for the heatlhy growth of hair and fur. Prolonged malnutrition may negatively influence all of these processes.
First and foremost, it is noticed that the coat of the animal seems to be dull and mat. The skin may also be affected and scales off increasingly.
In rare cases it may be found that an animal does not ingest enough vitamins with the food. In addition to such a mere under-supply, particularly animals are affected that just survived a disease with longer persisting vomiting or diarrhea.
At first it can be tried to reach an improvement by daily administration of a tablespoon of olive oil. It should, however, be examined whether possibly another disease or deficiency symptom might be responsible for the change of coat.