Skin: parasitic disease – overview

• One of the most common causes of dermatoses in dogs.
• Cause: parasitic infection.
• Signs: mild to severe skin lesions +/- systemic involvement, pruritus.
• Diagnosis: skin scrapes, identification of parasite, response to treatment.
• Treatment: effective use of antiparasitic agent.
• Prognosis: good with effective treatment.
• Non-parasitic insects can also be implicated.

• Reaction of skin to ectoparasitism varies from trivial to lethal but usually includes inflammation.
• Pruritus common.

• Owner lesions.
• Visualization of parasites.

• Systemic involvement.

• Dermanyssus gallinae Dermanyssus gallinae.
• Lynxacarus radovski(very rare in the dog, not in UK).
• Trombiculaspp Neotrombicula autumnalis , trombiculiasis Skin: neotrombicula autumnalis infestation.
• Otodectes cynotis Ear: parasitic otitis.
• Pneumonyssoides caninum.
• Cheyletiella yasguri Cheyletiella yasguri , cheyletiellosis Skin: cheyletiellosis.
• Demodex canis Demodex canis , demodicosis Skin: demodectic mange.
• Sarcoptes scabieivar.canis Sarcoptes scabiei , sarcoptic mange, canine scabies Skin: sarcoptic mange.

• Lice Pulex irritans , pediculosis Skin: pediculosis.
• Fleas Skin: flea bite hypersensitivity.
• Fly dermatitis.
• Mosquito dermatitis.
• Myiasis Myiasis.
• Cuterebraspp infestation.

• Ancylostoma braziliense, Ancylostoma caninum(not seen in UK),Uncinaria stencephala, ancyostomiasis and uncinariasis, hookworm dermatitis.
• Pelodera strongyloides, pelodera dermatitis (not in UK).
• Strongyloides stercoralis, strongyloides stercoralis-like infection (one report, not in UK).
• Anatrichosoma cutaneum, anatrichosomiasis (only in Africa).
• Schistosomiasis (not in UK).
• Dracunculusspp, dracunculiasis (not in UK).
• Dirofilaria immitus, dirofilariasis Canine cardiopulmonary dirofilariasis (rare in UK - not endemic).
• Taenia crassiceps(one report, USA).
• Habronemiaspp (one report, USA).
• Gnathostoma spinigerum(one report, Australia).
• Lagochiascaris major(one report, Brazil).

• Argasid (soft) ticks Skin: parasitic disease - overview.
• Ixodid (hard) ticks Ixodes canisuga.

• Rickettsia rickettsii, Rocky mountain spotted fever (USA only).

• Leishmania canis Leishmania infantum , leishmaniasis Canine leishmaniosis (in imported dogs from Mediterranean countries).
• Caryosporaspp, canine caryosporosis (USA).
• Neospora caninum Neospora caninum , canine neosporosis Neosporosis (USA).
• Sarcocystisspp , canine sarcocystosis (USA).
• Babesiaspp, canine babesiosis Babesia canis.

• Environmental mites, egDermatophagoides pteronyssinus,Dermatophagoides farinae.
• Spiders.
• Bees.
• Wasps , see canine facial eosinophilic folliculitis and furunculosis Skin: eosinophilic folliculitis and furunculosis.
• Hornets.
• Moths.
• Ants.
• Caterpillars.

• Pruritus.
• Skin lesions.
• Deep pyoderma/cellulitis.

• Severe to mild pruritus.
• Localized, multifocal or generalized hair loss.

• Skin lesions on owner.
• Seasonal occurrence.
• Skin lesions on in contact animals.

• Dandruff.
• Observation of parasites, fleas, lice, ticks,Trombiculaspp, flies, mosquitoes or non-parasitic insects, eg bees, wasps, hornets, ants, caterpillars.
• Environmental conditions may be suggestive.
• Head-shaking/aural pruritus.
• Discharge from ear canal.

• Malodor.
• Depression.
• Housing of patient.

• Skin inflamed and edematous.
• Excoriation and alopecia as a result of pruritus.
• Erythema, pustules, papules and crust formation.
• Hyperpigmentation and lichenification in chronic cases.
• Scaling.
• Observation of parasites or other insects.
• Pinnal scratch reflex.

• Non-pruritic alopecia.
• Otitis externa.
• Pododermatitis.
• Regional or generalized lymphadenopathy.
• Nodule formation.
• Systemic signs.

• Skin scrape Scraping: skin : mites,Pelodora strongyloides.
• Skin squeezings for demodex.

• Otoscopic examinationforOtodectes cynotis Otodectes cynotis.
• Wet paper testfor fleas.
• Parasiticide therapeutic trial- regression of clinical signs, eg of flea or sarcoptes infestation, once flea control programme instituted.
• Knott's testfor microfilaria ofDirofilaria spp.

• Hookworm eggs.

• Atopy Skin: atopy.
• Pyoderma Skin: bacterial skin disease - overview.
• Seborrheic dermatitis.
• Dermatophytosis Skin: dermatophytosis.
• Malasseziadermatitis Skin: malassezia disease.
• Endocrine skin disease Skin: hyposomatotropism.
• Melanoma.
• Lentigo.
• Autoimmune diseases Skin: immunological disease - overview.
• Trauma and foreign bodies.
• Bullous impetigo.
• Sterile pyogranulomas.
• Acral lick dermatitis Skin: acral lick granuloma.
• Superficial necrolytic dermatitis.
• Hookworm dermatitis Ancylostoma caninum.
• Zinc responsive dermatosis Zinc deficiency.
• Leishmaniasis Canine leishmaniosis.
• Anatrichosomiasis.
• Nodular dermatofibrosis syndrome.

• Neoplasia Skin: neoplasia.
• Contact irritant dermatitis Skin: allergic contact dermatitis.
• Food hypersensitivity Skin: food hypersensitivity.
• Drug eruption.

• Generally good with adequate therapy.

• Resolution of pruritus within days.
• Skin lesions reducing over weeks.

• Incorrect diagnosis.
• Inadequate treatment by owner.
• Concurrent disease untreated, eg pyoderma and parasitic infection or parasitic infection secondary to atopy.

Refereed papers

• Recent references from PubMed and VetMedResource.

Other sources of information

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