Pruritis Flashcards
how do we figure out if an animal is pruritic?
- presence of secondary lesions:
-excoriations (self induced erosions or ulcers)
-self induced alopecia
-lichenification, hyperpigmentation - presence of broken hair tips on trichograms
- presence of hair embedded between teeth
- presence of hair in feces
- behaviors:
-scratching
-biting
-licking
-chewing
-nibbling
-head shaking
-rubbing
what are the main causes of canine pruritis?
- parasitic dermatoses
-scabies (sarcoptic acariasis, sarcoptic mange)
-other ectoparasites - infectious dermatoses:
-bacterial pyodermas
-malassezia dermatitis - allergic dermtoses
-flea allergy dermatitis
-atopic dermatitis (with or without food allergies
describe distribution of pruritis and skin lesions in canine scabies/diagnosis
lesion distribution:
1. head and ears (ears!!!!)
2. ventral (chest /armpits>abdomen)
3. lateral sides limbs (hocks, elbows)
lesions: papules, alopecia, excoriations, lichenification, erosions, crusting
-mites live in superficial epidermis
-is ZOONOTIC: so is suspect scabies, ask if owner or anyone else in house is itching too!
-dx via skin scrape!
–if scrape and don’t find mites, rely on history and clinical presentation; if consistent with scabies, proceed with treatment
describe treatment for scabies
- topical acaricides:
-selamectin spot on
-topical/oral isoxazolines
-lime sulfur dio
-amitraz dips - systemic acaricides
-isoxazoline
-ivermectin
-milbemycin
recall side effects of these!
describe canine cheyletiellosis
- walking dandruff, predominantly on dorsum
- distribution of pruritis and skin lesions:
-dorsum!!
-chin
-perianal - treatment: anything that works for scabies will work
describe flea allergy dermatitis
- lesions distribution in dogs:
-caudal! tail head and dorsum
-some caudal ventral inguinal area - lesions: papules, alopecia, excoriations, lichenification, hot spots/pyotraumatic dermatitis
- must treat environment as well as the dog!!
-remember to clip the lesions before treatment so topicals can actually help!!
describe canine atopic dermatitis and diagnosis
the most common allergic, inflammatory, and itchy skin disease in dogs
-may be hereditary
diagnosis:
1. made clinically
- presence of suggestive history and compatible signalment
-age at onset, seasonality, recurrent skin/ear infections, previous response to glucocorticoids - utilize Favrot’s clinical criteria
-consider limitations as these criteria were developed for clinical trials/standardization - presence of characteristic clinical signs and lesion distribution pattern
- rule out resembling pruritic and inflammatory diseases
-ectoparasites, lymphoma
describe Favrot’s clinical criteria for diagnosis of canine atopic dermatitis
- onset of signs under 3 years old
-but sudden environment change could cause onset older! - dogs living mostly indoors
- glucocorticoid-responsive pruritis
- alesional pruritis at onset
- affected front feet
- affected ear pinnae
- nonaffected ear margins
- nonaffected dorso-lumbar area
5 criteria = 85% Se, 79% Sp for AD but NOT 100%
describe common signalment of cAD
- breed disposition
-variable in time and location
-breed to breed variation: not all breeds will have ALL locations affected
-GSD: most commonly inguinal and interdigital
-frenchies: armpits and interdigital - age of onset
-commonly 6 months to 3 years
-adult onset rare but possible - no gender predisposition
describe lesion distribution of cAD
- eyes/periocular
- chin/ventral neck
- inner ear: recurrent ear infections are a common problem
- armpits
- inguinal region
- ankles/elbows
- digits and pawpads
- UNDER the tail
dorsum is the least affected unless develop a secondary pruritic disease as well
describe itch and primary lesions in cAD
- majority of dogs have moderate to severe itch
-seem to have increased density of intraepidermal nerve fibers
-some itch without primary lesions! - primary lesions:
-erythematous macules and patches (eczema)
-micro-papules - secondary lesions:
-excoriations
-lichenification
-hyperpigmentation
-self-induced alopecia - different disease severities between every case!
-clinical heterogeneity - atypical signs:
-unilateral ear infections without AD signs
-recurrent pyoderma without AD signs
-adult-onset AD
describe the use of allergy tests in cAD diagnosis
types:
1. intradermal allergy test: immediate reactions 15 and 30 min post injection
- serum IgE allergy testing for environmental/food allergens
-more common in private practice
the tests often yield different results!
use:
1. not used to diagnose AD (false positives in healthy dogs possible)
2. atopic-like dermatitis: negative intradermal test and normal serum IgE
3. used only for allergen immunotherapy selection and avoidance measures
what are the 2 main factors that cause cAD?
- etiological factors:
-mites, pollens, molds
-foods
-cannot clinically distinguish between factors - flare factors:
-mites, pollens, molds
-foods
-fleas
-bacteria, yeast
what do:
1. for non-seasonal AD signs: perform a diet trial to differentiate food-induced AD
2. for environmental-induced AD: perform allergy testing for allergen immunotherapy formulation
3. for every AD patient, consider all flare factors and address accordingly!
describe the treatment approach for cAD
- ID and address all flare factors
-fleas: - symptomatic treatment of itch and/or inflammation
-topical and systemic medications
-use drugs with highest evidence for clinical efficacy for reversal of AD pathogenesis and symptomatic control of AD based on published data
-other symptomatic therapy works in mild cases but as standalone treatment usually fails
-but drugs that are considered to be equal do not perform the same clinically! - prevention of the disease flares/causative treatment
-food avoidance for immunotherapy
describe clinical phenotypes of food allergy in dogs
- skin:
-rash
-erythema
-urticaria/angioedema
-pruritis - GI:
-nausea
-mild abdominal pain
-V/D - upper airway:
-sneezing/itching
-sniffing
-rubbing nose/eyes - lower airway: increased breathing
- general: anaphylactic shock
-food is a very likely trigger in very few anaphylactic patients, insect bites are a much more common trigger!
currently, we cannot clinically differentiate between food and environmental induced AD so EVERY atopic dog with nonseasonal signs should undergo at least one restriction-provocation diet trial!
-however food is rarely the sole cause of AD, more likely a flare factor
describe the ideal elimination diet trial for food-induced AD
phase 1:
-initiate elimination diet with UNFLAVORED medications
-use any medications to resolve all secondary complications
phase 2:
-once resolve clinical signs, taper of medications and stop
-then no meds for at least 2 weeks
phase 3:
-provocation: re-challenges with old diet for maximum of 2 weeks
phase 4: return to elimination diet
phase 5:
-blinded provocation re-challenges for a maximum of 2 weeks (we don’t tell owner what they are feeding)
-most commonly used ultamino (ultra-hydrolyzed) and elemental (oligopeptide) diets
describe allergen immunotherapy
- only causal therapy for environmental induced AD
- subcutaneous (every 1-2 weeks) or sublingual (twice daily)
