Parasitic skin disease: overview

• One of the most common causes of dermatoses in cats.
• Cause: exposure of skin to ectoparasites +/- allergenic nature of parasite +/- excretory products.
• Signs: range from mild to severe skin lesions +/- systemic involvement.
• Diagnosis: identification of parasite by naked eye, microscopy or fecal examination.
• Treatment: parasiticides.
• Prognosis: good.

• Pruritus.

• Erythema and edema.
• Alopecia Alopecia: overview.
• Miliary dermatitis Dermatitis: miliary   .
• Eosinophilic granuloma complex Eosinophilic granuloma complex.

Arthropods

• Ticks :
  • Argasid (soft) ticks.
  • Ixodid (hard) ticks  .
• Mites :
  • Dermanyssus gallinae Dermanyssus gallinae.
  • Lynxacarus radovsky Lynxacarus radovsky.
  • Trombiculaspp (trombiculiasis) Neotrombicula autumnalis infestation.
  • Otodectes cynotis Otodectes cynotis.
  • Cheyletiella blakei (cheyletiellosis) Cheyletiellosis.
  • Demodex cati (demodicosis)  Demodectic mange also short Demodex species.
  • Notoedres cati (notoedric mange)  Notoedres cati (head mange).
• Sarcoptes scabiei (sarcoptic mange)  Sarcoptic mange.
• Spiders Spider bites .
• Insects :
  • Lice (pediculosis) Pediculosis.
  • Fleas Flea bite hypersensitivity.
  • Fly dermatitis.
  • Mosquito dermatitis.
  • Myiasis Myiasis.
  • Cuterebra spp infestation.

Hymenoptera 

• Bees.
• Wasps.
• Hornets.
• Moths.
• Ants.
• Caterpillars.

Helminths

• Ancylostoma braziliense, Ancylostoma caninum, Uncinaria stenocephala (ancyostomiasis and uncinariasis, hookworm dermatitis).
• Pelodera strongyloides (pelodera dermatitis).
• Anatrichosoma cutaneum (anatrichosomiasis).
• Schistosomiasis.
• Dracunculus spp. (dracunculiasis).
• Lagochilascaris major.

Rickettsia

• Haemobartonella felis (feline haemobartonellosis) Mycoplasma haemofelis, 'Candidatus Mycoplasma haemominutum' and 'Candidatus Mycoplasma turicensis'.

Protozoa

• Toxoplasma gondii (toxoplasmosis) Toxoplasmosis.
• Leishmania spp (leishmaniasis) Leishmania donovani.
• Sarcocystis spp (feline sarcocystosis).

• Pruritus.
• Pruritic alopecia and excoriation.
• Erythema.
• Pustules and papules.
• Crusts.
• Hyperpigmentation.
• Lichenification.
• Scaling.
• Non-pruritic alopecia.
• Otitis externa Otitis externa.
• Pododermatitis.
• Lymphadenopathy.
• Local edema.
• Nodules.

• Excessive grooming.
• Scratching.
• Localized, multifocal or generalized hair loss.
• Dandruff.
• Scab formation.
• Observation of parasites (fleas, lice, ticks, Trombicula spp, flies, mosquitoes, bees, wasps, hornets, ants, caterpillars).

• Skin lesions on owner.
• Seasonal occurrence.
• Head shaking.
• Discharge from ear canal.
• Crusts.
• Hyperpigmentation.
• Malodor.
• Depression.

• Severe to mild pruritus.
• Excoriation and alopecia as a result of self-trauma.
• Inflammation and edema.
• Erythema, pustules, papules and crust formation.
• Miliary dermatitis.
• Hyperpigmentation and lichenification in chronic cases.
• Scaling.
• Observation of parasites (fleas, lice, ticks, Otodectes cynotis, Trombicula spp, flies, mosquitoes, bees, wasps, hornets, ants, caterpillars).

• Symmetrical alopecia.
• Non-pruritic alopecia.
• Eosinophilic granuloma complex.
• Otitis externa.
• Hyperesthesia.

• Pododermatitis.
• Regional or generalized lymphadenopathy.
• Nodule formation.
• Systemic signs.

Other

• Coat brushing positive for flea feces  - wet paper test .
• Microscopy:
  • Skin scrape Scraping: skin: mites.
  • Acetate strippings: mites and/or eggs.
• Otoscopic examination
  • Otodectes cyonitis.
• Parasiticide therapeutic trial:
  • Regression of clinical signs of flea infestation.

Fecal analysis

• Hookworm eggs Fecal analysis: parasites.

Pruritus, pruritic alopecia and excoriation

• Fleabite hypersensitivity Flea bite hypersensitivity.

Pustules, papules, crusts, hyperpigmentation, lichenification and scaling

• Fleabite hypersensitivity Flea bite hypersensitivity.
• Dermatophytosis Dermatophytosis.

Non-pruritic alopecia

• As for alopecia Alopecia: overview.

Otitis externa

• As for otitis externa Otitis externa  .

Lymphadenopathy

• As for lymphadenopathy.

Nodules

• Foreign body reaction.
• Neoplasia Skin: neoplasia.
• Infection Bacterial skin disease: overview.

Pruritus, pruritic alopecia and excoriation

• Feline poxvirus Cat pox disease.
• Bacteria Bacterial skin disease: overview.
• Atopy Skin: atopic dermatitis.
• Food hypersensitivity Food hypersensitivity.
• Contact irritant dermatitis/hypersenstivity Skin: allergic contact dermatitis.

Pustules, papules, crusts, hyperpigmentation, lichenification and scaling

• Feline pox virus Cat pox disease.
• Bacteria Bacterial skin disease: overview.
• FIV Feline immunodeficiency virus disease, FIP  Feline infectious peritonitis, FeLV   Feline leukemia virus disease.
• Feline acne Feline acne.
• Atopy Skin: atopic dermatitis.
• Food hypersensitivity Food hypersensitivity.
• Contact irritant dermatitis/hypersensitivity Skin: allergic contact dermatitis.
• Tail-gland seborrhea Stud tail.
• Cutaneous neoplasia Skin: neoplasia.
• Immune-mediated skin disease Skin: immunological disease - overview.
• Drug eruption Drug eruption.
• Solar dermatitis Dermatitis: solar.

Non-pruritic alopecia

• As for alopecia Alopecia: overview.

Otitits externa

• As for otitis externa Otitis externa.

Pododermatitis

• Infection Bacterial skin disease: overview.
• Trauma and foreign bodies.
• Irritant contact dermatitis Skin: allergic contact dermatitis.
• Acral lick dermatitis.
• Bacteria Bacterial skin disease: overview.
• Hypersensitivity Skin: immunological disease - overview.

Lymphadenopathy

• Lymphadenopathy.

Nodules

• Eosinophilic granuloma complex Eosinophilic granuloma complex.
• Arthropod-bite granuloma.

Pruritus, pruritic alopecia and excoriation

• Neoplasia Skin: neoplasia.
• Contact irritant dermatitis/hypersensitivity Skin: allergic contact dermatitis.
• Mosquito hypersensitivity.
• Essential fatty acid deficiency  Skin: fat responsive dermatosis.
• Hypereosinophilia Hypereosinophilia.
• Malassezia dermatitis Malassezia pachydermatis.
• Collagenolytic granuloma (linear form).

Causes of pustules, papules, crusts, hyperpigmentation, lichenification and scaling

• Contact irritant dermatitis Skin: allergic contact dermatitis.
• Lentigo.
• Impetigo.
• Drug eruption Toxic epidermal necrolysis.
• Primary keratinization disorders.
• Nutritional disorders.
• Low humidity.

Non-pruritic alopecia

• Alopecia Alopecia: overview.

Pododermatitis

• Plasma cell pododermatitis Plasma cell pododermatitis.
• Autoimmune diseases Skin: immunological disease - overview.
• Drug eruption Drug eruption.
• Hookworm dermatitis.
• Neoplasia Skin: neoplasia.
• Anatrichosomiasis.

Local edema

• Burns Burns.
• Frostbite Frostbite.

Nodules

• Xanthomatosis.
• Panniculitis Skin: panniculitis.
• Sterile nodular granuloma and pyogranuloma.
• Leishmaniasis Leishmaniasis.
• Spider bite.
• Dracunuliasis.
• Cuterebra larvae.

• Antiparasitic drugs Therapeutics: parasiticide.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Messinger L M (1995) Therapy for feline dermatoses. Vet Clin North Am Small Anim Pract 25 (4), 981-1005 PubMed.
• Noxon J O (1995) Diagnostic procedures in feline dermatology. Vet Clin North Am Small Anim Pract 25 (4), 779-799 PubMed.
• Power H T & Ihrke P J (1995) Selected feline eosinophilic skin diseases. Vet Clin North Am Small Anim Pract 25 (4), 833-850 PubMed.
• Foley R H (1991) Parasitic mites of dogs and cats. Comp Contin Educ 13 (5), 783-800 VetMedResource.

Other sources of information

• Nesbitt G H and Ackerman L J Dermatology for the Small Animal Practitioner. Veterinary Learning Systems Co, 1991. p 32. (Excellent Table of common parasitic diseases with history, clinical signs and diagnosis.)
• Scott D W, Miller W H and Griffin C E Muller and Kirk's Small Animal Dermatology. 5th edn. Philadelphia: W B Saunders Company, 1995. pp 392-468. (Detailed dermatology text book for in-depth reading.)
• Guaguere E & Prelaud P (2000) Guide Pratique de Dermatologie Feline Lyon: Merial.