SAM II Final Exam - Dermatology Flashcards
T/F: Enrofloxacin (Baytril®) is a good first choice systemic antibiotic for treatment of deep pyoderma
False
Enrofloxacin is a good pyoderma drug, but really should only be used if no other antibiotic is a feasible option. Use of fluoroquinolones and 3rd generation cephalosporins increase risk for emergence of MRSA
What is the best way to diagnose eosinophilic granuloma complex?
cytology
confirm the lesion as part of eosinophilic complex
A dog presents with these lesions on its elbows and ears. What is your top differential?
sarcoptic mange
What is the most common perpetuating factor associated with lick granulomas?
deep pyoderma
most common and important; treat empirically with anti-staph antibiotic (first tier) or base selection on C&S results
T/F: Culture and sensitivity (C&S) test is indicated in all cases of bacterial pyodermas
False
-
Indications
- Cytology shows cocci and rods or just rods
- Cocci but no response to right AB administered at right time at right dose
- Deep pyoderma
- Chronic AB/GC therapy
- GSD pyoderma
What systemic antibiotics are considered 1st tier for empiric therapy?
- 1st generation cephalosporins (Cephalexin)
- Amoxicillin/clavuanic acid (Clavamox)
- Clindamycin
What secondary infections are commonly seen associated with allergic dermatitis (atopy)?
Staph pyoderma, Malassezia, Otitis externa, lick granulomas
What is the most important diagnostic test to perform if you suspect acute otitis externa?
CYTOLOGY
What is the drug of choice for systemic treatment of dermatophytosis?
Itraconazole
- Treatment of choice 5‐10 mg/kg sid, or pulsed therapy: 1 month solid; then 1 week on/off.
- Systemic treatment should continue until 2 neg cultures 1 month apart
- Onychomycosis may require 6 – 9 months treatment
Flea allergy dermatitis (FAD) has a fairly characteristic clinical presentation, but what is a more definitive diagnostic test that can be performed?
flea antigen test
- Elevated serum flea allergen-specific IgE. A negative does not rule out FAD!
-
Intradermal flea allergy test - 3 injections:
- Negative control (saline)
- Positive control (histamine)
- Flea antigen
Which of the following are primary skin lesions?
- Macule, papule and ulcer
- Papule, wheal and plaque
- Nodule, abscess and erosion
- Plaque, erosion and wheal
- Crust, erosion and ulcer
papule, wheal and plaque
What are the two most commonly used topical antibiotic shampoos?
benzoyl peroxide and chlorhexidine
How does sebaceous adenitis typically present in short-coated dogs?
moth-eaten appearance
annular areas of scaling/alopecia (moth-eaten appearance) that sometimes coalesce; intermittent edematous swelling of muzzle, lips, eyelids
Psychogenic alopecia in cats most commonly affects these areas:
medial thighs, ventral abdomen, medial forelimbs
T/F: The vertical canal is the ideal site for cytology samples for diagnosing otitis externa
False
The horizontal canal is the ideal site
A 3 year old dog presents with pruritus. Which of the following tests is least indicated?
- Adrenal testing
- Skin scraping
- Cytology
- Flea comb
adrenal test
Do we use a superficial or deep skin scraping to diagnose sarcoptic mange?
superficial skin scrape
A DSH cat from a multi-animal household is presented to your practice with facial pruritus. On examination of superficial skin scraping, you see the following organism. What is your diagnosis?
Demodex gatoi
Why do we use benzoyl peroxide to treat secondary pyoderma associated with localized demodex?
Benzoyl peroxide FLUSHES the follicles
T/F: There is strong evidence of efficacy regarding use of corticosteroids for treatment of allergic dermatitis (AD), and dexamethasone is recommended over prednisolone because of dexamethasone’s long duration of action
False
- There is strong evidence of efficacy regarding use of corticosteroids for treatment of allergic dermatitis (AD), but dexamethasone is not recommended over prednisolone, specifically because of dexamethasone’s long duration of action*
- With prednisolone, you’re able to have more control over the dosing due to the shorter duration of action*
Most cases of generalized demodicosis that occur at 2‐4 years of age are likely undiagnosed ___________
juvenile‐onset demodicosis
T/F: Before performing a skin biopsy, it is important to prep and scrub the area to ensure you get a viable sample
FALSE
You will not prep or scrubs for skin biopsies! You don’t want to disturb the superficial layers of the skin
What is that?
Indolent ulcer (rodent ulcer)
What skin condition occurs secondary to hyperadrenocorticism and can be more quickly resolved with the use of topical DMSO?
Calcinosis cutis
T/F: Chin acne (chin pyoderma) in dogs is typically a deep pyoderma
True
Usually Staphylococcus
- Signalment: young dogs (<1 year)
- Clinical signs: alopecia, non-painful, non-pruritic comedone, papules, discharge
-
Treatment:
- Mild cases: topical benzoyl peroxide
- Severe cases: topical benzoyl peroxide & systemic antibiotics
__________ is the most common underlying disease in adult onset generalized demodicosis
Cushing’s (hyperadrenocorticism)
What is the underlying cause of Alopecia X?
Unknown (hence why it’s called Alopecia X)
Recurrent flank alopecia, also known as __________ results in marked uni- or bilateral hyperpigmentation and is primarily seen in Boxers, English Bulldogs, and Airdales
Seasonal Follicular Alopecia
T/F: Culture may be indicated for surface pyoderma
False
Culture is never really indicated for surface pyoderma
What are the three major screening tests for diagnosing dermatologic conditions?
skin scrape, cytology, culture
For what type of pyoderma do we always recommend a culture?
deep pyoderma
Dermatophytosis can be treated both topically and systemically. You should ideally continue therapy until:
1 or more NEGATIVE FUNGAL CULTURES
What is the best way to diagnose sterile nasal eosinophilic folliculitis/furunculosis?
biopsy
What is the typical age of onset and lesion distribution associated with allergic dermatitis (atopy)?
- Age of onset: 1-3 years (same as FAD)
- Lesion distribution: face, ears, ventrum, feet, antebrachium, perineum
What dermatologic screening test would be indicated if you suspect yeast?
cytology
What is the most common bacteria associated with superficial pyoderma?
Staphylococcus
If you’re performing an intradermal allergy test in your patient, there are a few things to keep in mind:
- Avoid antihistamines and essential fatty acids for _______ before
- Avoid oral and topical steroids for at least _______ before
- No bath for at least _______ before
- Avoid antihistamines and essential fatty acids for 2 weeks before
- Avoid oral and topical steroids for at least 1 month before
- No bath for at least 5 days before
What are the two forms of canine demodicosis?
-
1. Localized
- 1 body location
- 5 or less lesions at that location
- < 50% of area affected at that location
-
2. Generalized
- > 1 body location
- > 5 lesions if only 1 location
- > 50% of area affected if only 1 location
T/F: With proper adulticide treatment and shampooing, dogs can be cured of FAD
False
A dog with FAD will always have FAD. It’s a hypersensitivity to flea bites, so it can be managed, but you can’t get rid of it.
If you suspect a food allergy in your patient and you want to perform a food trial, what should the minimum duration of the trial be?
4 weeks
- 4 weeks minimum to start
- No other food source
-
Expect: 50% reduction in pruritus
- < 50%: unlikely CAFR but continue for another 4 weeks
- Any improvement: continue for 4‐8 more weeks
- Trial of 3‐6 months if complex case
What is the most likely primary cause of lick granuloma?
atopy, food allergy
-
For treatment:
- Symptomatic treatment for atopy/food allergy = glucocorticoids
- Topical steroid may help with inflammation
T/F: Mupirocin is used topically and is effective against Gram-positive bacteria, including MRSA
True
Mupirocin is a mixture of several pseudomonic acids. It is bacteriostatic at low concentrations and bactericidal at high concentrations
Name three possible treatments for allergic dermatitis (atopy):
- Allergen-specific immunotherapy (ASIT)
- Symptomatic relief
- Allergen avoidance
________ is the most common cause of primary otitis
allergic dermatitis (atopy)
allergic dermatitis (atopy) is the most common cause of primary otitis
This topical medication is commonly used on burns and has activity against several bacteria including pseudomonas:
silver sulfadiazine
Pyodermas can be separated into types based on the layer of skin they affect. What type of pyoderma is shown below?
deep pyoderma
- The image shows a lick granuloma (acral lick dermatitis)*
- Folliculitis/furunculosis and lick granuloma are the two main examples of deep pyoderma*
A dog presents with alopecia on its caudal dorsum. What is your highest differential?
flea allergy
T/F: Intradermal testing is essential for diagnosis of allergic dermatitis (atopy)
FALSE
Clinical signs make the diagnosis for atopy. Intradermal testing is useful for determining what allergens the patient is allergic to
A dog presents for feet licking, chewing. What are your top two differentials?
atopy or food allergy
What are the three important factors for otitis externa (Three P’s of OE)?
primary, predisposing, and perpetuating
A 2 year old dog presents with a bilaterally symmetrical truncal alopecia and is not pruritic. Which of the following diagnoses is most likely?
- Alopecia X
- Pemphigus
- Demodex
Alopecia X
If you see this picture clinically, what two rule-outs should be on the top of your list?
DLE (discoid lupus erythematosus) and pemphigus foliaceus
You note a mild pustular rash in axillary and/or inguinal areas of a young dog. What is your top differential?
Impetigo (puppy pyoderma)
- Often associated with dirty environment, parasitism, etc.
- Usually self‐limiting
-
Mild cases usually respond to topical antibacterial shampoos
- Occasionally need systemic antibiotics
T/F: Topical antibiotics can be used for surface, superficial, and deep pyodermas
True
Bacterial culture of pyodermas are never contraindicated. When are they mandatory?
- If < 50% improvement with 2 wks treatment
- New lesions after 2 wks of treatment
- Residual lesions at 6 wks
- Intracellular rods on cytology
- History of MRSA
Injection site alopecia is associated with what vaccines?
rabies and lepto vaccines
- Hair loss at injection site or in a distant location
- Diagnosis: biopsy (characteristic histopathology)
- Treatment: oral pentoxyfylline
What part of the skin is affected by this lesion?
surface of the skin
- The image shows a pyotraumatic dermatitis (hot spot)
-
To treat this:
- Eliminate trigger (fleas, stress, etc.)
- Clip hair, clean with antibacterial shampoo
- Topical antibiotics/steroid creams/sprays
-
Short course corticosteroids to break ‘itch cycle’
- NOTE: this is not what we would typically treat pyodermas with
What is the preferred diagnostic method for the feline fur mite (Lynxacarus radovsky)?
- Diagnosis: acetate tape
- Treatment: pyrethrin spray, lime sulfur dips, Ivermectin, Selamectin
What is the treatment of choice for familial dermatomyositis?
pentoxyfylline
- Dermatomyositis is inflammation of the skin and underlying muscle tissue
-
Ischemic dermatopathy in Collie and Sheltie breeds primarily
- Pentoxyfylline improves microcirculation
When using Wood’s lamp to investigate ringworm, what color are you looking for?
apple green
- 50% of M. canis strains produce tryptophan metabolites that cause hair shaft to fluoresce apple green with ultraviolet (UV) light*
- Other ringworms don’t fluoresce*
T/F: 90% of generalized demodex cases usually resolve on their own
False
90% of localized demodex cases usually resolve on their own/don’t require treatment
How do you diagnosis demodicosis in the dog?
deep skin scrape
(Remember: in the cat, D. gatoi is a surface dweller. So in the cat, you would diagnose demodex with a superficial skin scrape)
Pyodermas can be separated into types based on the layer of skin they affect. What type of pyoderma is shown below on this puppy?
superficial pyoderma
- The image shows impetigo (puppy pyoderma).*
- Impetigo and superficial bacterial folliculitis are the two main examples of superficial pyoderma*
What do serum and intradermal allergy tests detect?
allergen-specific IgE
-
Allergy testing should be done:
- If clinical diagnosis of AD is made
- If allergen‐specific immunotherapy (ASIT) is being considered
- If allergen avoidance measures are consideration
How do you diagnose sebaceous adenitis?
skin biopsy from dorsal surfaces
What is the gold standard test for identifying environmental allergens?
intradermal testing
What are the three presentations of eosinophilic granuloma complex in the cat?
- Indolent ulcer (rodent ulcer)
- Eosinophilic plaque
- Collagenolytic granuloma
Fungal infection of the nail is termed:
onychomycosis
gross.
What is the standard medical treatment for eosinophilic granuloma complex in cats?
glucocorticoids (Pred: 2mg/kg BID)
- Note: Symptomatic therapy is NOT ideal before strict parasite control!*
- Note that this pred dose is much higher than we use in the dog. Cats are more resistant to the effects of corticosteroids.*
What is the typical presentation of endocrine alopecia?
Bilaterally symmetrical truncal alopecia
Not pruritic unless secondary pyoderma, seborrhea, Malassezia
What are the primary lesions associated with flea allergy dermatitis (FAD)?
papules
T/F: Benzoyl peroxide is indicated for pyoderma with dry seborrhea
False
Benzoyl peroxide dries out the skin. Chlorhexidine would be a better choice for pyoderma with dry seborrhea