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The pruritic dog (Proceedings)

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Apr 01, 2010

Pruritus

1. Unpleasant sensation that provokes desire to scratch.
2. Most common symptom in dermatology
3. Epicritic (sharp, specific) vs Protopathic (generalized) itch
4. Frustrations often makes this a multiple veterinarian disease!

Pruritic Dermatoses

Allergic dermatitis
Parasites
Infectious
Neoplasia
Hormonal diseases?
Drug eruption
Immune mediated
Must make accurate diagnosis for effective treatment
History and owner assessment is very important

Allergic Dermatitis

1. Flea Allergy - Used to be most common, is it still?
2. Atopy – Second most common?
3. Adverse Reaction to Foods
4. Contact Allergy – rare, does it occur in cats?

Food Allergy?

Adverse reaction to food maybe a better name
Not all food reactors are immunologic
Not all immunologic food reactors are IgE mediated
Clinical signs similar to atopics
Test diet length from 4-10 weeks
Eukanuba KO
Eukanuba FP
Hills Z/D, D/D novel protein, Purina H/A
Royal Canin diets
Home-cooked diets
20% of food reactors may only exhibit otitis externa
80% of food reactors have otitis externa
Serologic tests are worthless
IDAT
Gastroscopic Testing

EARS AND REARS?

Parasitic Dermatoses

Scabies
Demodicosis
Cheylitiella
Otodectes
Pediculosis
Helminths

Scabies

Intense pruritus in the dog
Lateral elbows, hocks, ventral thorax and ear margins are most common affected areas
Usually! poor response to GCC therapy, may actually cause mites to increase
Contagious to other pets and humans (especially if dog sleeps in bed with owner)
Physical examination
Skin scrapings of nonexcoriated papules usually best areas to find mites (ear margins and ventral thorax)
Always treat if suspect
Ivermectin, Selamectin (Revolution), Moxidectin (Advantage Multi),
Lime Sulfur dips

Infectious Dermatoses

Staphylococcus - Staph allergy/hypersensitivity is rare, often thought must show vasculitis on dermatopathology
Malassezia – Allergy to antigens or fermatation products. Desensitization Candidia
Dermatophytosis – Rare, usually T. mentagrophytes

Neoplasia

CTCL – Variable from none to extreme
Mast Cell Tumor

Hormonal Dermatoses

Hypothyroidism?
Cushing's Disease?
Calcinosis cutis – can often be very pruritic. Especially a problem if Iatrogenic.
Sertoli Cell Tumor – Rare, but some cases of hyperestrogenism are pruritic

Drug Eruption (variable pruritus)

TMS
Cephalosporins
Erythema multiforme
TEN – Most severe form, often fatal