Contributors: Karen Campbell, David Scarff
Species: Canine | Classification: Diseases
Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading
Introduction
- 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.
Presenting Signs
- Reaction of skin to ectoparasitism varies from trivial to lethal but usually includes inflammation.
- Pruritus common.
- Owner lesions.
- Visualization of parasites.
- Systemic involvement.
Pathogenesis
Etiology
Mites
- 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.
Diagnosis
Presenting Problems
- Pruritus.
- Skin lesions.
- Deep pyoderma/cellulitis.
Client History
- 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.
Clinical Signs
- 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.
Diagnostic Investigation
Microscopy
- 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.
Differential Diagnosis
- 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.
Treatment
Outcomes
Prognosis
- Generally good with adequate therapy.
Expected Response to Treatment
- Resolution of pruritus within days.
- Skin lesions reducing over weeks.
Reasons for Treatment Failure
- Incorrect diagnosis.
- Inadequate treatment by owner.
- Concurrent disease untreated, eg pyoderma and parasitic infection or parasitic infection secondary to atopy.
Further Reading
Publications
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).