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Flashcards in multifocal alopecia Deck (20):

Pathophys/description of:
Bacterial folliculitis

Superficial pyoderma, usually secondary to another dz (atopic dermatitis, keratinization disorders, endocrinopathy, etc.).


Common anatomical sites affected by bacterial folliculitis?

Perineum, perioral skin, nasal passage


Most common etiologic agent causing bacterial folliculitis?

Staphylococcus psuedintermedius (opportunistic)


Clinical signs of bacterial folliculitis?

multifocal alopecia.

FOLLICULAR papules/pustules.

epidermal collarettes that evolve into crusts, scales, hyperpigmented macules.

moth-eaten appearance in short-haired dogs;

scales, dull hair, hair loss (increased shedding) in long haired dogs.


diagnosis of bacterial folliculitis

History, clinical signs, cytology of lesions.
Response to emperic antibiotics.
Biopsy and culture - may need if non-responsive.


treatment of bacterial folliculitis

Topical: chlorhexidine, ethyl lactate, benzoyl peroxide. Use daily if sole therapy; 1-3x week if adjunct.

superficial - 4-6 weeks
deep - 8-12 weeks
keep treating until 1 week beyond clinical resolution.


First line antibiotics for emperic Tx of bacterial folliculitis

Cephalexin - 25-30 mg/kg BID;
Cefpodoxime - 7-10 SID

Clindamycin - 11 mg/kg BID

Amoxicillin-clavulonic acid - 20-25 mg/kg BID


Need a culture and sensitivity before prescribing which drugs?

TMZ/SMZ; rifampin, amikacin, doxycycline, chloramphenicol, fluoroquinolones


Bacterial culture is appropriate for which situations of bacterial folliculitis?

There is a long Hx of antibiotic use (recurrence)

Lesions remain after full course of abx

deep pyoderma is present


Mechanism of resistance of MRSA

Staphylococcus aureus organisms acquire mecA gene, which codes for PBP2a (=penicillin binding protein). Organism gains resistance to all beta-lactam drugs.


Pathophys/description of Demodicosis

Cause by Demodex mites. Normal commesal organism in the hair follicles of most animals.
With normal function of innate immunity, does not cause a problem. If immunosuppression or stressful event occurs, may develop clinical disease.


2 species of Demodex mites that have been ID'd in dogs

D. canis and D. injai


name and describe the different clinical 'syndromes' of Demodicosis, and list the clinical signs that may be seen with any type

- transient
- focal overgrowth of mites (= 1-4 areas of focal alopecia <2.5 cm diameter +/- erythema)
- young puppies often
- no systemic dz
- benign neglect, self-limiting

- any age
- multifocal or generalized overgrowth
- minimal pruritis unless 2' bacterial infection
- +/- systemic signs + peripheral lymphadenopathy

juvenile onset
- 1-2 years of age
- suspected to be genetic defect -> immune dysfunction -> overgrowth of mites
- American Staffordshire

adult onset
- >2 years of age
- immune dysfunction or immunosuppressed
- seen with Hyperadrenocorticism or other endocrinopathies, neoplasia, immunosuppressive therapy

Clinical signs of all:
- alopecia with variable erythema
- comedones
- may have concurrent bacterial infection (pruritis, erythema, pyoderma, papules, pustules, epidermal collarettes, crusting, draining tracts)


diagnosis of demodicosis

- Hx, PE
- deep skin scraping: should be easy to see mites on 4x or 10x
- Bx, histopathology
- fancy people: Trichoscopy/trichogram (but less sensitive than deep skin scraping so really you're just costing people $$$)


Key features of Demodex injai

- longer opisthosoma than D. canis
- see D. injai more than D. canis in terrier breeds
- found in sebacious glands -> marked hyperplasia
- greasy dorsal stripe
- mild to severe pruritis


treatment for demodicosis

- benign neglect, monitor, +/- topical abx/shampoo

Amitraz and ivermectin no longer TOC...
- ivermectin toxicity in MDR mutants

Moxidectin (Advantage Multi) weekly


Abx if 2' infections present

continue Tx until 2 (-) deep skin scrapes 2 weeks apart

* Adult-onset: must determine and Tx the underlying cause


Common etiologic agents of dermatophytosis

Microsporum canis
M. gypseum
Trichophyton mentagrophytes


Which causative agent of Dermatophytoses is zoonotic?

Microsporum canis


Dermatophytosis is an uncommon cause of focal to multifocal alopecia; when it does occur, it most common in dogs with ___?

immature immune system

Also Yorkies


describe the 2 presentations of dermatophytosis

Squamous form
- multifocal alopecia,
- erythema,
- scaling,
- hyperpigmentation if chronic
+/- pruritis

Fungal kerion
- solitary or multiple alopecic, circular, erythematous, exudative plaques
+/- pruritis