Flea Allergic Dermatitis and Flea Control
Flea allergy continues to represent the most common hypersensitivity in dogs in the UK. This time of the year almost 50% of skin conditions are due to fleas in some form or other. Regional variations occur but the common factors are warm temperatures and high humidity.
Flea allergy does occur on its own, but tends to exaggerate a coexisting skin condition with intensive itchiness as being the common factor.
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Fleas commonly infesting dogs are the cat flea or Ctenocephalides felis. This flea is well adapted and often exist quiet compatibly with the host without producing skin irritations unless an allergic reaction is induced. If an allergic reaction developes, then itchiness is the main or primary symptom. This reaction is due to 2 factors. One which is the allergic reaction triggered by the fleas saliva ( being a protein it induces an antibody : antigen reaction) and histamine/anyzyme-like compaounds which have an irritant effect. The allergic reaction devolopes an immunoglobulin responsewith the production of both IgG and IgE
The chief complaint in all flea related reactions is an intense itch with compulsive biting, chewing and licking particularly in the pelvic area. If this is noted a rigorous investigation for fleas should be started, examining both the dog and the environment. Cats who can live quiet happily heavily infested with fleas, should be the first home pets to be examined and treated.
A lack of commitment by the pet owner to sustained parasite treatment is often the major factor of ongoing or recurrent clinical disease. There are 3 explanations that account for the majority of failure to control flea allergies. First the program of flea control is inadequate. Second, pet owners may not believe the clinical problem is related to the flea . Thirdly, the owners may assume they are doing a good job of flea control even thought they are not. It is important to to determine the cause of failure and treating those before any further investigation.
A good physical examination may not find many fleas. This is true with any allergic reaction, in that once a sensitivity to an allergen has developed , it only take a tiny bit of the allergen at re-exposure to result in a massive itch reaction!!
The diagnosis of flea allergic dermatitis is based on historical information in combination with the classic dermatological pattern affecting the pelvic region and lower back.
Flea identification may be difficult if treatment has just been applied, but a good flea comb will facilitate demonstrating the flea.
Treatments for fleas involve many different application. From pour-ons/spot/ons to aerosol sprays. Insecticidal powder to shampoos and flea collars to oral treatments which work though the blood stream. Oral treatments can both kill fleas or inhibit there development but preventing metamorphosis to the final active adult phase.
Flea control does not just rest with the treatment of the host only.
Guy Liebenberg BSc BVSc MRCVS Cert Vet Acu
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