What is animal allergy?
All fur-bearing animals, and hence most domestic pets, can trigger allergic reactions. Individuals may react, not only to the hairs in the coat, but also to allergens (proteins) from the animals sebaceous and salivary glands. These are small airborne particles which mix with other airborne dust. When this air is breathed in it can give rise to allergic reactions. Dust from horses, dogs and cats contains 10-20 different allergy-provoking substances.
Who can get animal allergies?
Hereditary factors play a role in determining to what extent an individual is predisposed to animal allergies. In the presence of a family history of allergy, there will be an increase in the risk of developing allergy to any household pets obtained. If the individual’s father or mother has a cat allergy for example, the risk of the child developing an allergy to fur-bearing animals is increased. Where both parents are allergic, and have the same type of allergy, the risk of the child developing allergy will be closer to 80%.
The risk of developing animal allergies is greatest among small children. Animal allergy is most common among asthmatics, and in such individuals occurs along with mite allergy. If the child has not displayed any sign of allergy by the age of 12-14 years, the likelihood of him or her developing animal allergy is probably slight. Adults too can develop animal allergy.
It is difficult to predict to which animals individuals will react. In order to develop allergy one must first have been in contact with the specific allergen, and it may be some time before development of symptoms occurs. Until recently it was believed that allergy was most commonly related to allergens, into which individuals come into frequent and close contact, and normally those found in the home. Of course, the greater the quantity of animal allergens, the greater the risk of developing allergy. Recent research, however, has demonstrated that exposure to allergens at a young age may provide a degree of protection against subsequent allergy development. Currently this is an area requiring more research.
Sensitivity versus allergic illness
We differentiate between so-called sensitisation and manifest allergic illness. Sensitisation means that one has developed sensitivity to an allergen. With allergy testing this is shown as a positive reaction to the allergen. This sensitivity may however be so minimal that no symptoms develop on contact with the allergen. In other words, there is no obvious allergic illness. For example, we estimate that between 10 % and 15 % of the Norwegian population are sensitised to cats. There are, however, not that many individuals who develop allergic symptoms on contact with cats.
Which animals can trigger allergy?
Most domestic animals, including miniature pigs, hairless mice, chinchillas and short-haired Chinese poodles will, as stated, have potential to trigger allergy. Small animals such as mites, mosquito larvae and cockroaches can also trigger allergy.
Horses and cats possess the allergens which provoke the strongest reaction in individuals with animal allergies. The horse is a large animal and produces larger quantities of allergens than small animals. Cats have a large radius of movement and will spread the allergens wherever they travel. Dogs live in closest contact with people and therefore cause the most common form of animal allergy. There is a difference between how much and which type of allergens the various breeds of dog give of, but all breeds of dog - small or large, short- or thick-coated – produce allergens.
The only domestic animals which do not provoke allergy are aquarium fish and reptiles, e.g. turtles. In Norway the import of reptiles is banned, however the Norwegian Food Safety Authority permits the importation and keeping of some types of turtle, where allergy is given as the reason for keeping a turtle. The ban on sale of reptiles in Norwegian pet shops still applies. Other types of animals have been introduced as allergy-friendly pets, e.g. tropical millipedes. It is hard to recommend such animals as pets because the animals can cause discomfort of the skin and eyes, and harbour undesirable parasites.
Diagnosis
A blood test or skin-prick test must be performed in order to establish whether an individual has an allergy towards an animal. If allergies towards other animal species already exist, then such a test will have a positive outcome. It is not possible to test in advance whether a child will be tolerant to a specific animal. A negative skin-prick test cannot predict the possibility of future reactions.
Symptoms and treatment
Common reactions are blocked, runny nose, itching and runny eyes and asthma. Some individuals may also suffer eczema and nettle-rash. Exposure to cat allergens has been shown to be a particular risk factor for acute asthma.
Removal of the allergy-provoking animal from the allergic individual’s environment is the most effective treatment. Prevention of animal allergy with medications such as cortisone nasal spray and/or antihistamines, either in tablet form, nasal spray or eye drops, is not an ideal solution, but may be necessary where exposure to the animal allergen is unavoidable.
Immunotherapy or so-called allergy vaccination, where dog or cat allergens are injected under the skin, may have a favourable short-term effect. (See Useful facts on allergy vaccination.)
Prevention/protection
In the case of proven allergy to a fur-bearing animal, the first preventive advice should be to avoid getting a pet. Where an individual belongs to a risk group, i.e. where there is a family history of proven allergy, one should be cautious about obtaining a dog or cat. In such cases it is also important to be meticulous about domestic hygiene in order to eradicate the majority of the animal allergens which enter the house via clothing and hair.
If, for example, one has a cat which produces the “stickiest” and most volatile allergens and this is removed from the household, some effects will be noticeable immediately because the cat itself continually gives of relatively large quantities of allergens. However, even with normal domestic cleaning it will be 12-16 weeks before the level of allergens falls below the level which can give rise to illness. More extensive cleaning measures, e.g. removal of carpeting and furniture and washing of floors and walls, may, however, remove the allergens more rapidly.
Pet allergens are difficult to avoid completely because animal hair sticks to clothing and thereby finds its way to schools, kindergartens and public transport.
If the children have animal allergies, the kindergarten staff and teachers should ask other parents to dress their children in clothing which has not been in contact with animals. It is also important that outer clothing be hung in the corridor and not be taken into the classroom. There should be a general ban on cats and dogs in kindergartens and schools.
Cat bath?
Various cleansing agents which can be applied to the animal (PetalCleanse), in particular in respect of cats, have been launched as agents against animal allergy. By dampening the animal’s coat with a liquid the allergens are encapsulated and the quantity of allergens on the animal is reduced. The quantity of allergens in the coat of a cat is also reduced by normal washing and bathing, but this is not recommended as a treatment for animal allergy. In a best case scenario the washing agent will help temporarily and will be relevant for the milder forms of animal allergy. Even though the cat has been washed, cat allergens will still be present in the house dust. Another issue is that frequent washing of the animal may be perceived as animal cruelty.
Can animals protect against asthma and allergies?
Results from more recent studies suggest that keeping pets at an early stage in life, and before the age of 18 months, may protect against the development of asthma and allergy. The results are explained as being due partly to the fact that tolerance may be developed to the animal allergen and partly to the animal bringing with it various types of bacteria which can strengthen the immune system. The results thus far, however, have been inconclusive. More research is required in this area before it will be possible to recommend that someone obtain a pet in order to prevent asthma and allergy.
If one has initially developed an allergy towards dogs or cats, the most important preventive advice is to avoid all further contact with the species. If a pet has been brought into the household prior to the birth of the child, but where there is concern that the child will develop asthma because of a family history of allergy, the issue of whether or not the animal should be kept is a decision for the individual. Remember that it can be hard to lose a pet once a bond has been formed with it. Hence, parents should also consider whether they are willing to take such a risk – if the child should develop an animal allergy. The Animal Relocation Organisation (FOD) can be contacted where necessary.