Generally, it is in the form of a skin irritation that may take some time to subside, at times even prove fatal. Pure breeds are known to be more prone to allergies as against cross breeds that are hardier. Allergens are not region specific and are in fact ubiquitous in terms of their existence. They are transmitted by a source that is called the carrier. Some common causes for an allergic reaction are contaminated or spoilt food, pollen, moulds, dust and feathers.
Insects are another source.
Insect stings as well the saliva of fleas and ticks are known to cause serious ailments. Mange is also an allergic reaction. Skin contact with chemicals like detergents, flea collars, insecticides and petroleum products also cause allergies. The most common allergic reaction is a rash. At times insecticides, which have high levels of DDT can cause a serious skin ailments especially around the tail.