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Canine Atopic Dermatitis, Screen Shot 2020-05-21 at 10.14.21 - Coggle…

- - - - acute onset pruritus
      - erythematous papules with a greyish yellow crust
      - predilection sites
        
        pinnal tips and margins
        
        elbows
        
        hocks
        
        ventral chest and abdomen
        
        focal/multi focal -> generalised
      - Self-trauma
        
        excoriation
        
        lichenification
        
        patchy alopecia
      - Chronic cases
        
        malaise
        
        weight loss
        
        lymphadenopathy
        
        crusting
    - - Positive pinnae scratch reflex highly suggestive
      - skin scrape
        
        identify
        
        faecal pellets
        
        eggs
        
        mites
        
        POORLY SENSITIVE
      - Several ELISA tests for sarcoptes specific IgG
        
        False negatives in early infestations (can take up to 4 weeks to develop an adequate titre)
        
        false positive in atopic dogs sensitised to Dermatophagoides spp.
    - - Miticidal treatment should include the affected animal, in-contact dogs, and environment
      - Licensed treatment
        
        spot on formulations given once monthly on 2-3 occasions
        
        selamectin
        
        imidacloprid/moxidectin
        
        safe for collies + other breeds sensitive to macrocyclic lactones at recommended dose
        
        may be treatment failures so may be more efficient following off license therapy every 2 weeks for 3 applications
      - off licence treatments
        
        Milbemycin oxime
        
        2mg/kg PO weekly for 305 weeks
        
        1mg/kg PO every other day for 2-3 weeks
        
        Ivermectin
        
        0.2-0.4mg/kg either weekly PO or every 14 days SC for 4-6w
        
        Moxidectin
        
        250 microgram/kg SC every 3 weeks or 400 microgram/kg PO twice weekly for 3-6w
        
        avoid in avermectin-sensitive breeds
      - Topical treatment
        
        more time consuming
        
        requires clipping/bathing to remove hair and crusts
        
        may not be safer
        
        Amitraz dip
        
        0.25% Fipronil solution
        
        useful in young/pregnant/nursing dogs where more potent treatments contraindicated
        
        2.5% lime sulfur
  - - - mites commonly found in interdigital regions, ventral abdomen, or folds at base of pinnae or tip of tail.
- - - - lack of specificity, most dogs with skin disease will react to substances
  - - - coat brush
      - hair pluck
      - skin scrapes
        
        necessary to rule out parasites
    - - cytology/culture
      - trial antimicrobial therapy
    - - CANNOT RECOMMENDED
        
        serological or intradermal tests to determine hypersensitivity to food allergens reliably
      - Food allergens can cause flares of AD in dogs
      - DIET TRIAL
        
        6-10 weeks
        
        perform in all perennial cases of AD
        
        Hydrolysed diet
- - - - Clinical diagnosis of atopic dermatitis
      - an injectable dog (conventional v sublingual)
      - perennial disease
      - motivated client (approx 2-9 months)
      - informed consent/relation to likely efficacy
    - - if client declines
      - medical therapy preferred by owner
    - - injection site reactions and anaphylactic shock rare
        
        may want to give first 5-6 doses in hospital and observe for 30 mins post injection.
      - increased pruritis after an injection indicates the dose is too high
      - mild reactions generally prevented by pretreating with antihistamines 2hr before injection
  - - - medium efficacy for combination of chloramphreniramine and hydroxyzine
      - adverse effects uncommon
        
        sedation
        
        GIT disturbances
        
        second generation drugs may induce potentially fatal cardiac arrhythmias
    - - synergistic effect with antihistamines
  - - - preferred control of erythema and pruritic
    - - more likely to cause PU/PD, polyphagia.
    - - secondary infection
        
        S.intermedius
        
        m.pachydermatitis
        
        flea
        
        sarcastic mange
      - flea exposure
      - hotter/more humid environment
      - exposure to higher antigen dose
      - development of calcinosis cutis
  - - - immunosuppressive
      - inhibit mast and eosinophil cell function
      - inhibit T lymphocyte function
    - - significant improvement within 3 weeks, continuing slowly until 6w.
    - - emesis
      - gingival hyperplasia
      - diarrhoea
      - papilloma-type lesions of epidermis
      - hirsutism
- - - - staphylococcal toxins may also contribute