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Canine alopecia - Coggle Diagram

- - - - hypersensitivities
        
        atopic dermatitis
        
        adverse food reaction
        
        flea bite allergy
      - ectoparasites
        
        sarcoptes
        
        cheyletiella
        
        lice
    - - staphylococcus spp
      - demodex
      - dermatophytes
      - malasezzia
      - leishmania
    - - post injection alopecia
      - dermatomyositis
      - alopecia areata
      - sebaceous adenitis
    - - hypothyroidism
        
        common
        
        dry, dull and brittle hair coat
        
        scaling
        
        lack of hair regrowth
        
        after clipping
        
        alopecia on bridge of nose, tail and friction areas
        
        hyperpigmentation
        
        weight gain/obesity (without polyphagia)
        
        lethargy
        
        mental dullness
        
        uncommon
        
        pyoderma
        
        facial myxoedma
        
        weakness
        
        exercise intolerance
        
        cold intolerance
        
        evaluation of HypoT
        
        patient with clinical signs compatible with hypoT and over 2 years old
        
        several factors (drugs and non-thyroidal illness) can alter the test results
        
        postpone thyroid evaluation until resolution of illness or withdrawal of drug
        
        send samples to lab that has validated assays
        
        lifelong treatment with lexothyroxin required
        
        thyrotoxicosis (associated with PU/PD, wt loss, panting, nervousness and tachycardia) is rare in dogs due to rapid metabolism and renal/hepatic excretion of thyroid hormones
      - hyperadrenocorticism
        
        atrophic skin, calcinosis cutis, comedones, prominent cutaneous blood vessels
        
        PU/PD, polyphasic, panting, pot belly, muscle atrophy, lethargy, testicular atrophy, abnorma; oestrus
        
        increased cholesterol, increased ALP, increased ALT, stress leukogram, dilated urine
        
        abnormal cortisol response to ACTH stimulation, LDDST and HDDST, increased UCCR, USS
        
        surgical adrenalectomy, or medical mitotane, trilostane
        
        low dose dexamethasone suppression test and ACTH stem sensitivity approx 90%
        
        test results affected by steroid therapy and this can also cause iatrogenic hyperA and atrophy of adrenal gland cortex this can be evaluated by lack of response to ACTH stem test
        
        urinary cortisol to creatinine ration useful in ruling out hyperadrenocorticism
        
        USS used to differentiate pituitary dependent hyperA from a functional adrenal gland tumour
        
        the origin of hyperA can be found in about 75% of dogs using HDDST
        
        if cortical levels are suppressed by HDDST in dog with confirmed hyperA, the diagnosis is pituitary dependent hyperA
        
        if cortisol levels are not suppressed by HDDST in dog with confirmed hyperA then dog can have either form - in this case --> abdominal USS or measure endogenous ACTH level
        
        ACTH stim test LDDST, UCCR
        
        normal response to ACTH, normal cortisol suppression with LDDST, normal UCCR
        
        dx of hyperadrenocorticism v unlikely
        
        exaggerated response to ACTH, no cortisol suppression with LDDST, several compatible lab changes and clinical signs
        
        probable hyperA
        
        HDDST, abdominal USS, endogenous ACTH conc
        
        no cortisol suppression with HDDST, low endogenous ACTH concentration, one enlarged adrenal gland
        
        1 more item...
        
        cortisol suppression w HDDST, elevated endogenous ACTH conc, 2 adrenal glands normal or increased in size
        
        1 more item...
      - hyperoestrogenism
        
        functional gonadal neoplasia or ovarian cyst topical or oral absorption from oestrogen cream applied to human skin
        
        hyperpigmentation, enlarged vulva, linear preputial dermatitis, gynaecomastia
        
        bone marrow suppression
        
        USS, radiography, histopathology (gonads)
        
        tx surgical neutering
        
        males w functional testicular tumour or bitches with cystic ovaries
        
        testicular tumours common esp in cryptorchid dogs
        
        sertoli cell tumours are most common to cause hyperoestrogenism leading to endocrine alopecia (1/3 of cases)
        
        metastases in fewer than 10% of cases
      - pituitary dwarfism
    - - coat colour linked
        
        colour dilution alopecia
        
        black hair follicular dysplasia
        
        red or black dobermann follicular dysplasia
        
        Rottweiler follicular lipidosis
      - non coat colour linked
        
        canine recurrent flank alopecia
        
        alopecia x
        
        breed associated follicular dysplasias
        
        Chesapeake bay retriever, irish water spaniel, pont audemer spaniel and Portuguese water dog
    - - telogen defluxion
      - anagen defluxion
      - pattern alopecia
      - neoplastic alopecia
- - - - flea medication or post injection reactions
      - if hair epilates easily in area of alopecia and nowhere else on body, this suggests folliculitis or inflammation of hair follicles
        
        ddx for folliculitis = bacterial skin infection, fungal skin infection, demodecosis
      - vaccination reaction may occur up to 6 m
      - drug induced alopecia may occur within a short time (weeks) of drug administration
- - - - biopsy to confirm diagnosis
        
        medication, treat infection/vasculitis
    - - skin scrapings
        
        negative for mites
        
        positive for mites
        
        treat demoted address cause in older dogs
      - fungal cultures
        
        positive
        
        treat for dermatophytosis
        
        negative
      - skin cytology
        
        yeast
        
        treat with anti yeast medication
        
        bacteria
        
        c+s treat
        
        bacteria and yeast
        
        treat both, may need bacterial culture
- - - - age of onset?
        
        over 2 years old
        
        blood work and biopsy
        
        under or equal to 2
        
        biopsy
    - - allergy work up
    - - elizabethan collar for 1 month
        
        hair regrowth
        
        yes
        
        allergy work up
        
        no
        
        blood work and biopsy