Skin Diseases Pruritic Notes

3. Skin Diseases - Pruritic

Definition :

The sensation that provokes the desire to scratch, rub, chew, or lick. Pruritus is an indicator of inflammed skin.

Clinical Signs

• History e.g. common complaint

• Scratching, licking, biting or chewing

• Evidence of self trauma and cutaneous inflammation may be necessary to make the diagnosis

• In cats, which can be secretive lickers, alopecia without inflammation, may be the only sign.

• Visible excoriations, erythema, alopecia, lichenification (chronic)

Causes :

Parasitic

• Fleas, scabies, demodex, otodectes, notoedres, cheyletiella, trombicula, lice, pelodera, endoparasite migration.

Allergic

• Parasite allergy, atopy, food allergy, contact allergy, drug allergy, "bacterial hypersensitivity".

Bacterial/fungal

• Staph. Pyoderma, Malassezia pachydermatis, Dermatophytosis.

Miscellaneous

• Primary and seconday seborrhea, calcinosis cutis, cutaneous neoplasia, immune mediated dermatosis and endocrine dermatosis can be variably pruritic.

Endocrinopathies generally cause non-pruritic dermatoses, while secondary seborrhea or pyoderma can elicit pruritus.

Diagnosis

• History and Physical exam

• Age

  • Young Flea allergy, scabies. Demodex, Ear Mites, Internal parasite hypersensitivity

  • Adults Atopy, Food Allergy, Pyoderma, Seborrhea

• Breed Predisposition

  • Golden Retrievers and Terriers Atopy

  • Sharpeis Demodex, pyoderma, atopy, food allergy

• Diet

  • Food allergies

  • Lipid def. may result in pruritis or exacerbate other conditions

• Environment other animals, parasites, dust mites

• Onset

  • Rapid Flea allergy, scabies, cheyltiells, chiggers, drug sensitivity

  • Slow Atopy, food allergy, pyoderma, seborrhea

• Intensity Flea allergy and scabies are highly pruritic

• Seasonality Atopy and flea allergy in summer

• Response to therapy ATB, diet change

• Patterns of skin lesions

  • Flea allergy dorsum, lumbosacral and caudal thighs

  • Scabies Ear margins and elbows

  • Food allergy Head and neck

Tests

• Skin scrapings, smears, tape preparations Mites and Yeasts

• Fungal culture dermatophytes

• Skin Biopsy

• Elimination diet food allergy

• Intradermal testing atopy

• Fecal Flotation intestinal parasites

• Trial therapy with ATB or CCS

Location of Lesions

Flea bite Flea Allergy

Pediculosis (lice)

Scabies

Demodex

Cheiletiella (Mite)

Trombiculosis (Mite)

Otodectes cynotis

Notoedres cati

Malassezia

Atopic Dermatitis & Food Allergy

Treatment

Note: Treatment depends on the cause

• ATB Synulox 10-14 days, Chlorhexidine

• Ketoconazole

• Antihistamines Cetirizine 7.10days

• Essential Fatty Acids, Hypoallergenic diet

• Glucocorticoids Can cause PUPD and polyphagia

• Scabies Lime sulphur dip, ivermectin

Medication :

Drugs and fluids :

Topical therapy - topical therapy is helpful in mildly itchy pets.

• For localized areas, sprays, lotions and creams are most appropriate.

• If the itching involves many areas, shampoos are the preferred means of application.

• Topical anesthetics may offer only a very short duration of effect.

Antibacterial shampoos...

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