Alopetic Notes

2. Skin Diseases - Alopetic Alopecia = the absence of hari from areas that normally has hair. * Can be focal, multifocal, diffuse or regional Causes Follicular Disease Primary Genetics * Hairless Breeds e.g Chinese crested * Congenital Hypotrichosis * Colour Dilution Alopecia Neoplasia Inflammatory * Auto immune skin dis. e.g. Pemphigus * Dermatophytosis Bacterial folliculitis Secondary to other Condition Endocrine Disorders * Hypothyroidism * Hyperadrenocorticism * Hyposomatotropism * Sex Hormone Imbalances o Hyperoestrogenism o Sertoli cell tumors Stress Nutritional * Malnutrition * Vit A def. * F.A. def. Systemic Disease Demodecosis 1. Alopecic Breeds * Generalized truncal alopecia at birth is typical. * Mild secondary pyoderma or seborrhea may develop in dogs. * Comedones are common. Treatment * Antiseborrheic follicular flushing (comedolytic) antibacterial shampoo for 20 seborrhea and pyoderma. 2. Hypoadrenocorticism (Cushing's) Etiology * Spontaneous - with excessive production of endogenous steroid hormones (glucocorticoids) o Cause = hyperfunctioning adrenal tumor (15-20%) or pituitary tumor(80-85%). * Pituitary dependent hyperadrenocorticism-(PDH) is caused by excessive production of ACTH from pituitary microadenoma or macroadenoma. * Iatrogenic - 20 to excessive administration of glucocorticoids e.g. in chronically pruritic dogs and dogs with immune-mediated disorders that are controlled with longterm glucocorticoids. Clinical Signs * Coat - Dry and lusterless. * Slow progressing, bilaterally symmetrical alopecia is common - may become generalized, but it usually spares the head and limbs. * Remaining hairs are easily epilated and alopetic skin is often thin, hypotonic and hyperpigmented. * Chronic 20 pyoderma , dermatophytosis or demodicosis common and may be the primary complaint. * Other: PU/PD, polyphagia, muscle weakness, hepatomegaly, increased susceptibility to infection (conjunctival , skin, urinary tract, lung), excessive panting an variable behavioral or neurologic signs are often present. Diagnosis: * Ne|, Ly|, Eo|, * Serum biochemistry panel: ALP|, ALT|, Chol|, Tg|, Glu|, * Urinalysis: the specific gravity is usually low and maybe bacteriuria, proteinuria or glycosuria. * Adrenal function test: ACTH stimulation test (cortisol)/ exaggerated poststimulation cortisol level is highly suggestive of endogenous HAC. * Low-dose (0,01mg/kg) and high-dose (0,1mg/kg) dexamethasone suppression test. A lack of cortisol suppression is suggestive of adrenal neoplasia. Treatment * Mitotane * Trilostane 3. Hypothyroidism * Is associated with primary thyroid dysfunction caused by ALT or idiopathic atrophy * Giant-breed dogs are occasionally affected Skin symptoms: * Hair coat may be dry, dull and brittle * Bilaterally symmetrical alopecia that spares the extremities, with easily epilated hairs * Alopetic skin may be hyperpigmented, thickened or cool to the touch * Alopecia on the bridge of the nose * Chronic seborrhea sicca or recurent otitis externa can by seen * Seborrheic skin and ears may be secondarily infected with yeast or bacteria * Noncutaneous symptoms-lethargy, mental dullness, exercise intolerance, obesity, cold intolerance, bradycardia Diagnosis * Hemogram and serum biochemistry panel : Low TT4, lowfT4, and high TSH are highly suggestive * Although TT4 = good screening test it shouldnt be used alone to make diagnosis because its serum level can be arteficially increased or decresed by severel factors, such as nonthyroidal illness, autoantibodies and drug therapy. 

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