How common are animal allergies?

In the United States, an estimated 40 to 50 million people currently suffer from allergies. Hypersensitivity to household pets is a common problem in the population as a whole, and in the research setting, allergies to laboratory animals (ALA) can become a serious concern. Among those whose education or occupation requires significant exposure to lab animals, ALA affects approximately one in five people.

What laboratory animal species can cause allergy problems?

Rats and rabbits are the most frequently implicated species, but mouse allergies are becoming more apparent, especially as the numbers of mice utilized increases and the research projects using them require more direct handling.

Cat and dog allergies may also be occupational if a research project includes those species, and it is possible to develop allergic reactions to most other species, including hamsters and ferrets, after chronic exposure.

I spend most of my time in the laboratory, and I only work with animals a few times a week. Can I still develop allergies?

Although it is true that people with very limited contact develop fewer problems, studies have shown that the problem of ALA can be just as severe in those handling animals for scientific purposes (research staff) as it is in those responsible for their primary care (caretaking staff).

I have problems with hay fever at certain times of the year. Does that mean that I’ll become allergic to animals?

A history of previous allergies (i.e. atopy) is not a guarantee that animal-related problems will develop, but some studies have found a correlation between pre-existing atopy and ALA.

How do I know if I have ALA?

The symptoms are generally evident six to 24 months after exposure but sometimes may take years to develop, and often worsen over time. Mild symptoms of ALA involve the eyes and nose (e.g. sneezing, runny nose, watery eyes) and/or the skin (itchy welts or rashes). Non-ALA allergies such as hay fever or an associated occupational allergy like latex hypersensitivity may cause ALA symptoms to worsen.

I don’t mind a few sniffles now and then when I’m around animals. Do I have anything to worry about?

These minor problems typically will not go away if the exposure to animal allergens does not change, and can ultimately progress to the most serious manifestation of ALA, which is animal-related asthma. Asthma is a serious, potentially debilitating problem, and it will predictably affect a percentage of workers who ignore the earlier symptoms of rhinitis or conjunctivitis (runny eyes and nose). Asthma is estimated to affect two percent of all people using animals during their first year of exposure, and an additional two percent per year thereafter.

What happens to people who develop serious problems?

ALA can have serious consequences for affected personnel, not just in terms of personal health, but in determining future career options as well. Studies have shown that about 50% of those with symptoms will eventually stop working with animals because of the discomfort involved with ALA. Many of those people can change career tracks or be reassigned to non-animal duties within the same institution, but as many as 15% of affected workers will eventually quit their jobs because of ALA. Manifestations of asthma may not completely subside until six or more months after ending contact with animals.

What causes these allergies?

It was previously thought that dog and cat allergies were provoked by dander or fur, but it is now known that the actual allergens are proteins in the saliva, which are present on the animals’ skin and hair. In the case of ALA involving rodents, the major allergens are low-molecular weight proteins excreted in the urine, which adhere to skin and hair. They can also be found in soiled bedding, and may be distributed as airborne contamination in rooms where animals are housed or manipulated.

What are the options for treating ALA?

There are three general approaches to allergy treatment:

• avoiding the allergen (through environmental control)
• medication to relieve symptoms
• immunologic desensitization (allergy shots)

Medications can provide relief, but the following should be kept in mind:

• Although there are over-the-counter drugs which can give temporary symptomatic relief, it is best to seek the advice of a physician before self-prescribing. Drugs can mask the warning signs of developing asthma and may also cause drowsiness.
• If you use an antihistamine, take the drug prior to exposure for best results.
• Other types of anti-allergy drugs that do not induce drowsiness are now available by prescription, if necessary. Standard allergy shots (immuno-therapy) to reduce allergic sensitivity to cats and dogs have improved in recent years, and may be a good choice for some people.

I have ALA and I want to continue working with animals. What can I do?

Allergen avoidance is the only complete solution to ALA. If avoidance is impossible, it’s critical that exposure is minimized as much as possible.

Many people with ALA are able to continue working with animals by taking some simple precautions, such as the following:

• Wear personal protective equipment, including a tight-fitting mask, gloves, and a long-sleeved lab coat (or other dedicated uniform) at all times when working with animals. In some cases, a respirator or a filtered air-supplied face mask may be warranted.
• Take advantage of filter-topped caging (if available in the facility) to contain allergens when animals are transported or held. An understanding of the proper use of ventilated workstations will help minimize aerosol exposure when cages are opened.
• Avoid unnecessary exposure to irritants such as dust, tobacco smoke, and air pollution, since irritant chemicals can worsen airborne allergy symptoms.
• If you are experiencing symptoms of ALA, specialized medical professionals are available to help evaluate and treat your problems.

I don’t have allergies now. Is there anything I can do to prevent them?

Procedures to minimize allergen contact (such as those listed above) should be followed by all exposed persons, even if ALA symptoms are not present, because this may prevent the development of clinical signs. At the very least, following these procedures may greatly slow the progression of ALA.

Why is my supervisor interested in my allergy status? Isn’t that my business?

Current federal guidelines require that all personnel beginning to work with animals be given information regarding ALA and the precautions that should be taken. ALA should be treated like any other occupational health hazard and personnel should notify their supervisors of known or potential work-related allergies. Clear procedures should be established in each facility for reporting all allergic reactions in the same way that accidents, bites, and scratches are reported.

Questions?

Any concerns or questions you have about working with vertebrate animals and allergies can be discussed with:

• SU Occupational Health Center at (650) 725-5308
• Stanford Environmental Health & Safety, at (650) 723-0448