multifocal alopecia

Question 1

Pathophys/description of:

Bacterial folliculitis

Answer 1

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

Question 2

Common anatomical sites affected by bacterial folliculitis?

Answer 2

Perineum, perioral skin, nasal passage

Question 3

Most common etiologic agent causing bacterial folliculitis?

Answer 3

Staphylococcus psuedintermedius (opportunistic)

Question 4

Clinical signs of bacterial folliculitis?

Answer 4

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.

Question 5

diagnosis of bacterial folliculitis

Answer 5

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

Question 6

treatment of bacterial folliculitis

Answer 6

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

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

Question 7

First line antibiotics for emperic Tx of bacterial folliculitis

Answer 7

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

Clindamycin - 11 mg/kg BID

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

Question 8

Need a culture and sensitivity before prescribing which drugs?

Answer 8

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

Question 9

Bacterial culture is appropriate for which situations of bacterial folliculitis?

Answer 9

There is a long Hx of antibiotic use (recurrence)

Lesions remain after full course of abx

deep pyoderma is present

Question 10

Mechanism of resistance of MRSA

Answer 10

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

Question 11

Pathophys/description of Demodicosis

Answer 11

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.

Question 12

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

Answer 12

D. canis and D. injai

Question 13

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

Answer 13

localized

• transient
• focal overgrowth of mites (= 1-4 areas of focal alopecia <2.5 cm diameter +/- erythema)
• young puppies often
• NOT PRURITIC
• no systemic dz
• benign neglect, self-limiting

generalized

• 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)

Question 14

diagnosis of demodicosis

Answer 14

• 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 $$$)

Question 15

Key features of Demodex injai

Answer 15

• 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

Question 16

treatment for demodicosis

Answer 16

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

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

Moxidectin (Advantage Multi) weekly

Isoxazolines

Abx if 2’ infections present

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

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

Question 17

Common etiologic agents of dermatophytosis

Answer 17

Microsporum canis
M. gypseum
Trichophyton mentagrophytes

Question 18

Which causative agent of Dermatophytoses is zoonotic?

Answer 18

Microsporum canis

Question 19

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

Answer 19

immature immune system

Also Yorkies

Question 20

describe the 2 presentations of dermatophytosis

Answer 20

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

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