There is still some controversy regarding exactly what substance causes the allergy in a certain individual. Early studies suggested that the allergies were mainly caused by dander and debris from the skin and far of an animal, but more recent studies seem to indicate that exposure to animal urine, saliva and fecal matter may be equally or more important. Exposure to animal urine can occur either through direct urine contact with skin, or more commonly, by inhalation of dust from the bottom of a cage which has been contaminated with urine or fecal material. People who have a prior family or personal history of asthma, hay fever, or eczema will be more likely to develop asthma after contact with animals, but these people do not seem any more likely to develop rhinitis or conjunctivitis than do people without such history. Because of this, it is necessary that everyone exercise certain precautions to attempt to prevent animal allergy.
Symptoms can develop anywhere from months to years after a person begins working with animals.
A majority of the individuals who are going to develop symptoms will do so within the first year. It is extremely unusual to develop symptoms after more than two years of animal contact. Certain procedures should be routinely followed in order to prevent the development of animal allergy. Animals should be worked with only in extremely well ventilated areas to prevent buildup of various particles in the air. Workers should always wear gloves and laboratory coats to prevent direct exposure to the animals.