L108: focal to multifocal alopecia

what are the inflammatory causes of alopecia?

1. self-induced

2. sequalae of folliculitis

3. immune-mediated disease

what are the non-inflammatory causes of alopecia?

1. disturbances of hair growth

2. hair cycle abnormalities

3. follicular dysplasia

4. post scarring

5. genetics

how does inflammatory alopecia distribute on the body?

appears focal to multifocal

how does non-inflammatory alopecia distribute on the body?

geographic to generalized

what are the differential diagnoses for inflammatory alopecia?

1. pyoderma

2. dermatophytosis

3. demodicosis

what is pyoderma in dogs?

bacterial infection of the skin secondary to underlying primary cause

what is pyoderma classified by?

depth of the infection in the skin

what is the most common primary cause that can lead to pyoderma in dogs?

allergies

what are the types of pyoderma based on depth of infection?

1. surface

2. superficial

3. deep

what is the depth of surface pyodermas?

upper layers of epidermis

what is the depth of superficial pyodermas?

epidermis and hair follicle

what is the depth of deep pyodermas?

dermis ± subcutaneous tissue

what are the clinical presentations of surface pyoderma?

1. pyotraumatic dermatitis

2. intertrigo

3. bacterial overgrowth syndrome

where do we typically see pyotraumatic dermatitis in the dog?

1. cheek

2. neck

3. thighs

4. rump

what are some clinical signs we may see in a dog with surface pyoderma?

1. erythema

2. exudate

3. matted hair

4. exudate

5. pruritis

what is the timing for a dog getting pyotraumatic dermatitis?

rapid onset

what are the clinical signs with intertrigo?

1. erythema

2. exudate

3. malodor in skin folds

what areas is it common to see intertrigo in dogs?

1. face

2. lip

3. vulva

4. tail folds

what breeds is it common to see intertrigo?

breeds with prominent skin folds

what clinical signs are seen with bacterial overgrowth syndrome?

1. erythema

2. exudate

3. lichenification

4. hyperpigmentation

where is it common to see bacterial overgrowth syndrome?

1. ventral abdomen

2. interdigital

3. pinnae

what is unique about the cytology for bacterial overgrowth syndrome?

bacteria without inflammation

what is the diagnostic approach for surface pyodermas?

1. clinical assessment

2. cytology

what will you see on cytology for a dog with pytotraumatic dermatitis and intertrigo?

cocci often with neutrophils

what will you see on cytology for a dog with bacterial overgrowth?

large number of bacteria with few or no neutrophils

why is a bacterial culture not needed necessarily for surface pyodermas?

topical treatment is always the treatment of choice

what is the preferred treatment for surface pyodermas?

chlorhexidine 2-4%

A 2 year old MN bulldog comes to the clinic for surface pyoderma. You prescribed topical antiseptic, but the patient is still pruritic. What is an additional treatment you can prescribe to the patient for its pruritis?

1. topical glucocorticoids

2. short course of systemic gluccocorticoids at anti-inflammatory dose for 5-7 days

what is the long term management for surface pyoderma?

1. address underlying cause

2. maintenance therapy of antiseptic topical therapy

what is important to understand about superficial pyoderma?

almost always secondary to a primary cause

what is the most common opportunistic pathogen for superficial pyoderma?

staphylococcus pseudintermdius

what are the clinical presentations of superficial pyoderma?

1. superficial bacterial folliculitis

2. exfoliative superficial pyoderma

3. impetigo

4. mucocutaneous pyoderma

what is the most common form of superficial bacterial folliculitis?

superficial bacterial folliculitis

what are the clinical signs of superficial bacterial folliculitis?

1. follicular papules

2. pustules

3. epidermal collarettes

4. “moth eaten” focal alopecia

what are the predilection sites for superficial bacterial follicultis?

1. ventral abdomen

2. medial thighs

what condition is shown in the image?

superficial bacterial folliculitis

what condition is shown in the image?

superficial bacterial folliculitis

what are the clinical signs of exfoliative superficial pyoderma?

1. large expansive epidermal collarettes with erythmea rim

2. target lesion appearance

what skin condition is shown in the image?

exfoliative superficial pyoderma

what skin condition is shown in the image?

exfoliative superficial pyoderma

what are the clinical signs of impetigo in puppies?

non-follicular pustules at the inguinal or axillary areas

what are the clinical sign of impetigo in immunocompromised adult dogs?

bullous impetigo

A 6 month old puppy comes to the clinic after an owner notices some skin issues. You do a physical exam and see the following lesion in the photo? What is your differential diagnosis?

impetigo; lesion is a non-follicular pustule

what is shown in the image?

bullous impetigo before a rupture

A 5 year old GSD comes to the clinic after the owner notices some skin issue along the mouth. You do a physical exam and see the following image. What is your differential diagnosis?

mucocutaneous pyoderma

what are the clinical signs of mucocutaneous pyoderma?

erythema, erosions, crusts at mucocutaneous junctions

what is the diagnostic approach for superficial pyoderma?

1. clinical assessment

2. cytology

3. bacterial culture and susceptibility (if doing systemic antibiotics)

4. rule out other follicular diseases

what other follicular diseases do you need to rule out for superficial pyoderma?

1. demodicosis

2. dermatophytosis

3. pemphigus foliaceus

what diagnostic tests do you use for demodicosis?

1. deep skin scarping

2. trichogram

what diagnostic test do you use for dermatophytosis?

1. wood’s lamp

2. fungal culture/PCR

what diagnostic test do you use for pemphigus foliaceus?

look for acantholytic keratinocytes

what is the treatment options for superficial pyoderma?

1. topical antimicrobial therapy

2. anti-inflammatory therapy

3. systemic antimicrobial therapy

what is the treatment of choice for superficial pyoderma?

topical antimicrobial therapy for 2-3 weeks until resolution

what is the only time we use systemic antimicrobial therapy for superficial pyoderma?

if topical therapy fails or is not feasible

what are the first-choice drugs for systemic antimicrobial therapy for superficial pyoderma?

1. cephalexin

2. clindamycin

3. amoxicillin-clavulanate (clavamox)

how long do you use systemic antimicrobial therapy for superficial pyoderma?

two week course with recheck before stopping therapy → can be stopped once primary lesions resolved

what are the clinical presentations for generalized deep bacterial pyoderma?

1. deep bacterial folliculitis/furunculosis

2. post grooming furunculosis

what are the clinical presentations for localized deep bacterial pyoderma?

1. acral lick dermatitis

2. interdigital furunculosis

3. pressure point/callus pyoderma

4. chin pyoderma

what clinical signs can be seen with generalized deep bacterial pyoderma?

1. hemorrhagic bullae

2. thick crusts

3. draining tracts

4. nodules

5. ulcers

6. scarring

7. varying degrees of pruritis

what regions can be affected with generalized deep bacterial pyoderma?

1. glabrous regions

2. interdigital spaces

3. chins

4. pressure points

what dog breed is predisposed to generalized deep bacterial folliculitis?

german sheperds

why may short-coated dogs get generalized deep bacterial folliculitis?

high friction areas create potential for skin injury and infection

what other clinical signs may be seen with general deep bacterial pyoderma?

1. fever

2. lethargy

3. lymphadenopathy

4. often painful

5. RISK OF SEPSIS

what is the most common agent for generalized deep bacterial pyoderma?

staphylococcus spp.

what other bacteria can cause deep infection for generalized deep bacterial pyoderma?

pseudomonas spp

what skin condition is shown in the image?

deep bacterial pyoderma

what breed is it more common to see post grooming furunculosis?

short-haired breed with stiff bristle hair

what happens with post grooming furunculosis?

mechanical rupture of hair follicles after brushing or bathing

when do lesions start to appear with post grooming furunculosis?

24-48 hours after bathing or grooming but can go unnoticed for several days

how do dogs with post grooming furunculosis often present clinically?

present to the ER for fever, anorexia, lethargy, and back pain

what common organisms can cause infection with post groom furunculosis?

1. pseudomonas

2. staphylococcus

3. proteus

4. serratia

where can we se acral lick dermatitis/furunculosis?

left carpal most common place

where can pressure point/callus pyoderma for local deep bacterial pyoderma present?

1. elbows

2. lateral hind leg/tarsus

3. shoulder

4. temporal

what patients do we see chin pyoderma in?

1. young dogs

2. short haired breeds

what skin condition is shown in the image?

acral lick dermatitis

what skin condition is shown in the image?

interdigital furunculosis

what skin condition is shown in the image?

chin pyoderma

what is the diagnostic approach for deep pyoderma?

1. clinical assessment

2. cytology

3. bacterial culture

4. rule out other follicular diseases

what are the treatment options for deep bacterial pyoderma?

1. systemic antimicrobial therapy

2. adjunctive topical and anti-inflammatory therapy

3. pain management

4. identification and management of underlying causes

what is systemic antimicrobial therapy based on?

• culture and susceptibility results

• always indicated with widespread lesions

what is the timeline for systemic antibiotics for deep bacterial pyoderma?

1. initial 3 week course with re-examination

2. continue until infection resolves (about 6 weeks)

what adjunctive topical and anti-inflammatory therapy will be prescribed for deep bacterial pyoderma?

1. antiseptics and PBM

2. glucocorticoids at anti-inflammatory dosing

what pain management can you give when indicated in cases of deep bacterial pyoderma?

1. gabapentin

2. topical anesthetics (lidocaine spray, EMLA cream)

what underlying causes can lead to deep bacterial pyoderma?

1. demodicosis

2. allergies

3. endocrinopathies

4. foreign bodies

You perform the following cytology from the pustule on the abdomen of a dog. You see numerous cocci in clusters, many with neutrophils. What is your interpretation?

superficial bacterial furunculosis

You perform the following cytology from an interdigital lesion on a dog. You see a moderate number of rod-shaped bacteria and a few cocci, with neutrophils showing nuclear streaming. What is your interpretation?

You perform the following cytology from erythematous skin on the ventral abdomen of a dog. You see a large number of cocci with minimal inflammatory cells. What condition might this represent?

surface pyoderma

where can cats develop bacterial overgrowth?

areas of skin that are traumatized (ulcerated or excoriated) → overgrooming or scratching

what is important to remember about cats and topical therapy?

often less tolerant of topical therapy

what is methicillin-resistant staphylococcus pseudintermedius (MRSP)?

Staphylococcus pseudintermedius organism that has developed resistance to ALL beta-lactam antibiotics

what is MRSP the consequence of?

Consequence of acquiring the mecA gene that produces PBP2a (penicillin-binding protein)

what are MRSP resistant to on susceptibility testing?

1. Oxacillin

2. Methicillin

3. all beta lactams → penicillins, cephalosporins, and carbapenems

what are the reserved antibiotics for treatment of MRSP?

1. rifampin

2. chloramphenicol

3. amikacin

4. gentamin

what must we do if we prescribe any of the reserved antibiotics for the treatment of MRSP?

blood work due to high risk of side effects

MRSP is NOT the same as…

MRSA

what is impractical and impossible with MRSP? what do we do instead?

• decolonization

• normal hygiene practices recommended instead

Is MRSP more virulent that MSSP?

NO! just more challenging to treat due to limited antibiotic options

what is the most common species of dermatophyte in dogs and cats?

microsporum canis

Bailey is a 4-year-old SF golden retriever presenting to the clinic with papules, pustules, and epidermal collarettes on her ventral abdomen and medial thighs. The owner mentions that she has moderate pruritis and a history of seasonal allergies. You decide to perform a cytology and see numerous cocci, many with neutrophils. You also decide to perform a bacterial culture and the results show heavy growth of staphylococcus pseudintermedius. What is the diagnosis and what will your treatment of choice be?

• diagnosis: superficial bacterial folliculitis

• treatment: chlorhexidine and cytopoint

what is dermatophytosis?

superficial fungal infection of keratinized structures (hair shafts and stratum corneum)