Flea allergy

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Hair loss in a cat with a flea allergy: The top hair has fallen out completely, except for the back.

The flea allergy  - even flea bite allergy , flea saliva allergy , flea allergic dermatitis or allergic flea dermatitis  - is through the saliva of fleas caused allergic skin disease, especially in domestic dogs and cats occurs. The main symptom is intense itching , which can lead to self-inflicted severe skin changes and secondary infections . The treatment is carried out by flea control and prophylaxis; glucocorticoids can be used against the itching for a short time .

Occurrence and pathogenesis

Cat flea

Flea allergies are a fairly common phenomenon in dogs and cats and are mainly caused by cat fleas (Ctenocephalides felis) , also in dogs . Animals of all races and ages are affected. Although the disease occurs more frequently in summer, it occurs all year round. An increased disease inclination have dogs at another allergy, the atopic dermatitis , suffer: About 80% of atopic dogs develop at flea exposure a flea allergy. Flea allergy also occurs in martens and occasionally in sheep and goats , with cat fleas also being the most common trigger.

Chronic flea allergy with secondary malassezia dermatitis in a dog: hair loss, skin thickening, and hyperpigmentation.

As allergens ( allergens ) are proteins and haptens from the saliva of the fleas with a molar mass of 6-58  kDa considered. The first identified allergenic flea saliva protein was composed of 158 amino acids existing Cte f 1 ( Cte f stands for Ctenocephalides felis ) having a molar mass of 18 kDa. A total of at least 15 different flea allergen genes are possible causes, the most frequently reacting genes have a molar mass between 25 and 58 kDa.

Flea allergy is largely an immunoglobulin E (IgE) -mediated type I reaction with degranulation of mast cells and an increase in eosinophilic granulocytes ( eosinophilia ). In an experimental study on laboratory mice, there was a close relationship between the amount of immunoglobulin E and the degree of clinical disease, with CD4-positive T lymphocytes and interleukin-4 playing a key role in the development of the disease. In individual cases, a type IV reaction can also occur. In addition, other immunological mechanisms are also discussed, such as a delayed cellular immune response to IgE and hypersensitivity of the skin with immigration of basophilic granulocytes and degranulation of these cells after IgE or IgG binding.

Clinical picture

The main symptom of flea allergy in dogs is intense itching , especially in the lumbar, groin and tail areas, to which the animals react with gnawing and licking. The first skin change ( primary fluorescence ) is a small papule . Occasionally there is a swelling of the popliteal lymph nodes . As a result of the gnawing and licking, further skin changes such as erosions and crusts, a so-called hot spot , a circumscribed, superficial purulent skin inflammation ( pyoderma ) develop . An overgrowth of the skin with Malassezia pachydermatis , a yeast of the natural skin flora , is observed more frequently, so that a secondary malassezia dermatitis occurs. With chronic flea allergy, hair loss , hyperpigmentation and skin thickening occur.

Miliary dermatitis in a flea allergy cat

In cats the clinical picture is more variable. The roots of the tail and loin, abdomen and groin as well as the neck are particularly affected. In addition to itching, the main symptom is inflammation of the skin with papules the size of millet grains and crusts ( miliary dermatitis ). Hypersensitivity ( hyperesthesia ) of the back can also indicate a flea allergy. With prolonged existence, patchy or bilateral symmetrical hair loss can occur. Intensive licking can cause extensive, raised reddening of the skin ( eosinophilic plaque ). A non-painful lip ulcer with immigration of neutrophils and secondary bacterial infection can also be an expression of a flea allergy. Flea allergy can also be associated with swelling of the lymph nodes in cats and cannot always be clinically differentiated from non-allergic dermatitis after exposure to fleas.

In sheep, a flea allergy manifests itself mainly in the limbs, in martens the clinical picture is similar to that of dogs.

Diagnosis

In addition to the clinical picture and a lack of flea prophylaxis, which must be inquired about, a flea comb can be used to detect fleas or flea droppings in the fur. Since fleas are not permanently on the host, a negative result is not yet diagnostically meaningful. In addition, cats in particular are able to quickly eliminate fleas thanks to their intensive grooming. However, since a single flea bite can trigger an allergy, this can be the sole indicator of flea exposure. Another indication is the evidence of the eggs of the cucumber seed tapeworm in the feces, as these need fleas as intermediate hosts.

Positive intracutaneous test

An intracutaneous test with highly purified flea saliva protein is most suitable for confirming the diagnosis. The sensitivity and specificity here is over 90%. Whole-body extracts from fleas have too little allergen content and with a sensitivity of 67% only a limited value. In the intracutaneous test, 0.05 ml of a test solution is injected into the skin. A wheal appears after 10 to 20 minutes if the result is positive , and in some animals only after 24 or 48 hours, so that the reaction should be checked three times. As a positive control , histamine is applied at another point . Previous treatment with glucocorticoids can lead to false negative results. In such a case, the test must be repeated after two weeks, or after six weeks for depot preparations. The disadvantage of this test is that an area of ​​skin has to be sheared for him and corresponding test solutions with a limited shelf life have to be kept in stock.

The diagnostic reliability of serological examinations of blood samples using ELISA is not without controversy. The sensitivity of 87% is quite high, but the specificity of 53% is insufficient. However, since they are more practical for the veterinarian, these tests are carried out more frequently than the intracutaneous test.

The provocation test, in which 10 newly hatched, sober and microbiologically harmless fleas are applied to the animal, is considered the “ gold standard ”, but this proof is not very practical.

therapy

The best therapy is consistent flea control. This can be achieved through regular use of long-acting insecticides (e.g. Afoxolaner , Fipronil , Fluralaner , Imidacloprid , Metaflumizon , Nitenpyran , Selamectin or Spinosad ), which are also used therapeutically in the event of an infestation. It is essential for treatment that the speed of kill is high and that the effect is sustained. Nitenpyran has a kill rate of 3 hours, but the effect already wears off after 2 days. Imidacloprid is effective after 8 hours and shows a persistently high level of killing over 14 days. Metaflumizone, selamectin and fipronil have a long effect, but the rate of destruction is relatively slow. Permethrin-containing preparations work after about 6 hours and show an effect for a month, but must not be used in cats. The newer oral antiparasitic drugs such as Spinosad, Afoxolaner and Fluralaner have very high kill rates and good sustained effects.

If infestation is proven, the animal's surroundings should also be treated, especially the resting place and preferred location, as fleas are not permanently on the animal and the effectiveness of the active substances applied to the animal is limited to this part of the flea population. The environment is treated by regularly vacuuming and washing blankets and carpets, supported by chemical flea control with chlorpyrifos , permethrin (not for cats), propoxur , fenoxycarb , methoprene or combinations of these active ingredients (e.g. Bolfo-Plus , Kadox , VetKem ).

Short-term anti-inflammatory glucocorticoids such as prednisolone can be used against acute symptoms twice at intervals of 48 hours ("2-day therapy"). For cats, Rosje and Willemse recommend a five-day dose of prednisolone. Antihistamines are mostly ineffective in dogs and cats because the itching is hardly mediated by histamine .

The previous studies on desensitization have shown unsatisfactory results, possibly because they were only carried out with whole-body flea extracts.

literature

  • B. Bigler: Flea Allergic Dermatitis . In: PF Suter and B. Kohn (eds.): Internship at the dog clinic . Parey, 10th ed. 2006, p. 373. ISBN 3-8304-4141-X
  • Ch. Noli and F. Scarampella: Flea bite allergy . In: Practical Dermatology in Dogs and Cats. Schlütersche Verlagsanstalt, 2nd edition 2005, pp. 264–267. ISBN 3-87706-713-1
  • PJ Rosje and T. Willemse: Flea saliva allergy . In: MC Horzinek (Ed.): Diseases of the cat. Enke, 3rd ed. 2003, pp. 296-297. ISBN 3-8304-1003-4
  • CA Sousa: Fleas, flea allergy, and flea control: a review. Dermatology Online Journal 1997 Dec; 3 (2): 7. ( Full text )
  • George T. Wilkinson and Richard G. Harvey: Color Atlas of Skin Diseases in Small Pets. Schlütersche, 2nd edition 1999. ISBN 3-87706-554-6

Individual evidence

  1. ↑ SE Lee et al .: Salivary antigens of the cat flea, Ctenocephalides felis felis. Parasite Immunol. 1997 Jan; 19 (1): 13-19. PMID 9121836
  2. ^ CA Sousa & RE Halliwell: The ACVD task force on canine atopic dermatitis (XI): the relationship between arthropod hypersensitivity and atopic dermatitis in the dog. Vet Immunol Immunopathol. 2001 Sep 20; 81 (3-4): 233-237. PMID 11553385
  3. ↑ W. Beck, N. Pantchev: Parasitoses of the Mustelids. In: Practical Parasitology in Pets. Schlütersche Verlagsgesellschaft, Hannover 2006, pp. 125–145, ISBN 3-89993-017-7
  4. ↑ a b I. Yeruham et al .: Seasonal allergic dermatitis in sheep associated with Ctenocephalides and Culicoides bites. Vet. Dermacol. 2004 Dec; 15 (6): 377-380. PMID 15585013
  5. ↑ I. Yeruham: An apparent flea-allergy dermatitis in kids and lambs. Zentralbl Veterinarmed A. 1997 Sep; 44 (7): 391-397. PMID 9360467
  6. ↑ SE Lee: Putative salivary allergens of the cat flea, Ctenocephalides felis felis. Vet Immunol Immunopathol. 1999 Aug 2; 69 (2-4): 229-237. PMID 10507308
  7. ↑ MJ McDermott et al .: Identification, cloning, and characterization of a major cat flea salivary allergen (Cte f 1). Mole immunol. 2000 May; 37 (7): 361-375. PMID 11074254
  8. ↑ a b c Stefanie Peters: Flea allergy (flea allergic dermatitis, FAD) - clinical picture, diagnosis and principles of therapy. In: Fachpraxis 34 (2010), pp. 4–5.
  9. ↑ MJ Wilkerson et al .: The immunopathogenesis of flea allergy dermatitis in dogs, an experimental study. Vet Immunol Immunopathol. 2004 Jun; 99 (3-4): 179-192. PMID 15135984
  10. ↑ K. Wuersch et al .: Immune dysregulation in flea allergy dermatitis - a model for the immunopathogenesis of allergic dermatitis. Vet Immunol Immunopathol. 2006 Apr 15; 110 (3-4): 311-323. PMID 16325922
  11. ↑ L. Zhao et al .: A rodent model for allergic dermatitis induced by flea antigens. Vet Immunol Immunopathol. 2006 Dec 15; 114 (3-4): 285-296. PMID 17011637
  12. ^ RE Halliwell et al .: Aspects of the immunopathogenesis of flea allergy dermatitis in dogs. Vet Immunol Immunopathol. 1987 Dec; 17 (1-4): 483-494. PMID 3433670
  13. ^ S. Colombini et al .: Induction of feline flea allergy dermatitis and the incidence and histopathological characteristics of concurrent indolent lip ulcers. Vet. Dermacol. 2001 Jun; 12 (3): 155-161. PMID 11420931
  14. ↑ a b c C. Laffort-Dassot et al .: Diagnosis of flea allergy dermatitis: comparison of intradermal testing with flea allergens and a FcepsilonRI alpha-based IgE assay in response to flea control. Vet. Dermacol. 2004 Oct; 15 (5): 321-330.
  15. ^ MK Rust: Advances in the control of Ctenocephalides felis (cat flea) on cats and dogs. Trends Parasitol. 2005 May; 21 (5): 232-236. PMID 15837612
  16. ↑ Kerstin Wildermuth: The importance of the speed of kill (SOK) in the treatment of allergic flea salivary dermatitis. In: Small Animal Practice . tape 61 , no. 7 , 2016, p. 366-372 .
  17. ↑ LJ Fourie et al .: Control of immature stages of the flea Ctenocephalides felis (Bouche) in carpets exposed to cats treated with imidacloprid. JS Afr Vet Assoc. 2000 Dec; 71 (4): 219-221. PMID 11212931
This article was added to the list of excellent articles on May 16, 2007 in this version .