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[[Image:Cat flea.jpg|thumb|right|150px|Cat Flea - August La Roux 2007,  Wikimedia Commons]]

[[Image:Cat flea.jpg|thumb|right|150px|Cat Flea - August La Roux 2007,  Wikimedia Commons]]

Flea allergic dermatitis is the most common skin disease of dogs and cats worldwide. Cases are caused by flea infestation, mainly by ''[[Ctenocephalides felis]]'', the cat flea, but ''[[Ctenocephalides canis]]'', ''[[Archaeopsylla erinacei]]'', ''[[Spylopsyllus cuniculi]]'' and ''[[Pulex irritans]]'' can also be found on cats and dogs. [[:Category:Fleas|Fleas]] are blood sucking, wingless insects that live and breed in the hair coat of an animal and often cause pruritus and annoyance. The term flea allergic dermatitis refers to the condition that arises due to hypersensitivity to flea saliva when a flea bites. This is initiated by a low molecular weight hapten and two high molecular weight allergens. Flea saliva also contains histamine-like compound that irritate the skin to cause flea bite hypersensitivity.

Flea allergic dermatitis is the most common skin disease of dogs and cats worldwide. Cases are caused by flea infestation, mainly by ''[[Ctenocephalides felis]]'', the cat flea, but ''[[Ctenocephalides canis]]'', ''[[Archaeopsylla erinacei]]'', ''[[Spilopsyllus cuniculi]]'' and ''[[Pulex irritans]]'' can also be found on cats and dogs. [[:Category:Fleas|Fleas]] are blood sucking, wingless insects that live and breed in the hair coat of an animal and often cause pruritus and annoyance. The term flea allergic dermatitis refers to the condition that arises due to hypersensitivity to flea saliva when a flea bites. This is initiated by a low molecular weight hapten and two high molecular weight allergens. Flea saliva also contains histamine-like compound that irritate the skin to cause flea bite hypersensitivity.

Intermittent exposure to fleas and saliva is far more likely to result in flea allergic dermatitis than continued exposure. Both IgG and IgE antibodies have been implicated in the reaction, and both immediate and delayed hypersensitivity reactions are seen. Cutaneous basophil hypersensitivity also becomes established: [[basophils]] infiltrate the dermis under the influence of IgG or IgE and degranulate upon subsequent exposures to give further immediate and delayed hypersensitivity.

Intermittent exposure to fleas and saliva is far more likely to result in flea allergic dermatitis than continued exposure. Both IgG and IgE antibodies have been implicated in the reaction, and both immediate and delayed hypersensitivity reactions are seen. Cutaneous basophil hypersensitivity also becomes established: [[basophils]] infiltrate the dermis under the influence of IgG or IgE and degranulate upon subsequent exposures to give further immediate and delayed hypersensitivity.