Derm 2: Food allergies, ectoparasites, otitis, cats (E2) Flashcards
What organisms cause dermatophytosis? What becomes infected and how is it transmitted?
Microsporum canis
- M. gypseum*
- Trichophyton metagraphytes*
Fungal infection of: Ketatinized tissues, claws, hair, stratum corneum
Transmission: Direct contact
T/F: Food allergic dermatitis is a cutaneous adverse food reaction whose pathogenesis is idential to atopy.
True
What 3 drugs do poloxamer otic gels contain?
Florfenicol
Terbinafine
Betamethasone acetate
Where do you often see symmetrical alopecia in cats with atopic dermatitis? Food allergic dermatitis? Scabies?
Atopic: Medial thighs, ventrum, forelimbs, flanks
Food: face, head
Scabies: pinna, face, neck, forelimbs, progressing to whole body
What etiology does coffee ground-looking ear discharge indicate? What if it is moist and brown? Creamy yellow? Oily yellow-tan?
How can you determine the cause definitively?
Coffe grounds: mites
Moist, brown: staph or yeast
Creamy yellow: Gram - bacteria
Oily yellow-tan: glandular disorder or HS
Cytology
What dermatologic presentations are associated with pruritus in cats? What are 2 common causes?
Bilateral symmetrical hair loss with normal (non-inflamed) skin
Miliary dermatitis
Eosinophilic granuloma complex
Causes: Fleas, Ringworm
Which 2 tests can you do to diagnose sarcoptes? Which one is better?
Fecal floatation (better)
Superficial skin scrape x 6 (extremely difficult to find mite)
What is the first line topical antibiotic choice for otitis externa? Why is it a problem when there is purulent exudate?
Neomycin-Polymixin (Surolan)
Polymixin doesn’t work in pus
What are the infectious causes of Feline Leprosy?
Nocardia
Actinomyces
Mycobacterium
Dermatomycoses
What specific diets is based on the theory that if particles are really small they cannot bind to the respective IgE particle on mast cells, preventing degranulation (i.e. allergic reaction)?
Hydrolyzed protein diets
How long do you treat superficial pyoderma? Deep pyoderma?
Superficial: 3-4 weeks minimum, 1 week post-resolution
Deep: 3-12 weeks, 2 weeks post-resolution
T/F: Ear cultures are indicated for all cases of acute otitis externa.
False, not usually if acute
Culture (and sensitivity) may be indicated in chronic recurrent or unresponsive cases
What are some common antibiotics used to treat deep pyoderma? Include any important side effects.
Amoxycillin-clavulanic acid (Bactericidal aminopenicillin with beta-lactamase inhibitor (clav) that expands its spectrum)
Cephalexin
Trimethoprim-sulphurs Side effects: Liver and renal damage (C/O’d if have issues with liver or kidneys), careful in Dobermans (immune disease), can crysallize urine, irreversible keratoconjunctivitis sicca, can cause hypothyroidsm in dogs (longterm use)
Enrofloxacin Side effects: GI distress; Cats- blindness
Erythromycin/Clindamycin/Lincomycin (Macrolides) Side effects: Careful in dogs w/MDR-1
Sort the following as either against generalized severe greasy seborrhea or dry-moderately greasy sebohhea.
KetoChlor (2% ketoconazole + 2% chlorhex)
Selenium sulfide (1%)
Miconazole (1-2%)
Head and Shoulders Instensive
Selsun Blue
Chlorhexidine (1-2%)
Greasy:
Head and Shoulders Instensive
Selsun Blue
1% Selenium sulfide
Dry:
KetoChlor (2% ketoconazole + 2% chlorhex)
Miconazole (1-2%)
Chlorhexidine (1-2%)
What are the 3 most common causes of folliculitis in dogs?
Bacterial
Dermatophytes
Demodex
What bacterium is involved in the pathogenesis of superficial pyoderma? Where does the bacteria colonize? What is the most common clinical sign?
Staphylococcus pseudintermedius
Superficial hair follicle
Alopecia (patchy, focal)
Which ectoparasite causes parasitic folliciculitis in dogs?
Demodex canis
What species of Malassezia causes dermatitis in dogs? Cats?
Dogs: M. pachydermatis
Cats: M. sympodialis, M. globosa
What is the best thing to culture in pyoderma?
Pustules
What combination of starch and protein appears to be the least allergenic?
Brown rice
Tofu
For which type of pyoderma is cytology often critical?
Deep
What gram positive filamentous aerobe causes subcutaneous absesses and draining tracts as well as pyothorax?
Nocardia
What is the source of infeciton if a dog develops opportunistic mycobacteriosis? What are the clinical signs?
Soil and water (saprophytic mycobacterium)
CS: Slowly developing SQ nodules, non-healing abscesses, cellulitis, ulcers, fistulas, serosanguinous/purulent exudate, regional LN enlargement
T/F: Prophylactic use of topical pyoderma therapy, such as shampoos, is indicated for recurrent pyodermas and they have little to no side effects.
True
What are 3 active ingredients of antibacterial shampoos used to treat superficial pyoderma?
Chlorhexidine
Ethyl lactate
Benzoyl peroxide
Which 3 antibiotics are 1st tier empiric therapy for pyoderma? Which are used as a last resort?
1st Tier:
Cephalexin (1st gen cephalosporins)
Amoxi-Clav
Clindamycin
Last Resort:
Fluoroquinolones (enrofloxacin, marbofloxacin, ciprofloxacin, orbifloxacin)
3rd gen cephalosporins (cefodoxime, cefovecin (SQ inj q1-2wks))
What is the most common cause of miliary dermatitis in cats? What are some viral causes?
Flea allergic dermatitis
Herpes, FIV, FeLV
T/F: Bacteria or yeast are usually the primary cause of acute otitis externa.
False
Pancreatic neoplasia in cats can cause symmetrical alopecia. What body parts are commonly affected and how does the skin look?
Ventrum and legs
“Shiny” skin, hair epilates easily
What is the term for “skin fold pyoderma”? Where do clinical signs manifest in various breeds?
Intertrigo
Spaniels: Lip folds
Bulldogs: Facial folds, tail root folds, vulva folds
Spar Pei: Body folds
How is dermatophytosis diagnosed?
Wood’s lamp
Microscopy of hair pluck
Fungal culture (DTM w/phenols that change color at higher pH)
Biopsy (for kerion type disease)
Seeing what on cytology warrants a bacterial culture of pyoderma?
Intracellular rods
T/F: M. canis, in addition to causing dermatophytosis in dogs and cats, is also the most common fungal infection in humans.
True (it’s zoonotic)
What is the most important pathogen in deep pyoderma?
S. pseudintermedius
What is indicated by the “A”, the arrow heads and the arrows? What is your diagnosis?
A: Soft tissue density in right typanic bulla
Arrowheads: Thickened wall of right bulla
Arrows: Mineralized external ear canals
Dx: Bilateral otits externa + Right sided otitis media and bulla osteoitis
Why may systemic antibiocs be ineffective for deep pyoderma? If antibiotics are warrented, what 4 rules should be follwed (include what organism you would treat first if multiple are cultured) ?
The pathogens tend to produce B-lactamase
Poor drug bioavailibility to skin
Infection walled off by fibrotic tissue and exudate
Rules:
- Use B-lactamase resistant penicillins
- If multiple organisms are cultured - treat S. pseudintermedius first
- Dosage must be high enough, may exceed recommended dose
- Treatment is long
You perform a cytology for a skin rash and it reveals degenerative neutrophils, phagocytosed cocci, and a proteinaeous background. What type of pyoderma does this suggest?
Superficial
What are the 3 ways you can treat sarcoptes? Name one specific treatment for each category.
Topical dips: Anti-seborrheic shampoo followed by 2-3% lime sulfur, Amitraz
Topical spot-on treatment: Selamectin (Revolution), Moxidectin (Advantage multi), Fipronil
Systemic treatment: Milbemycin (Interceptor, Sentinel, Trifexis), Ivermectin
You want to examine a dog’s ears using an otoscope, however swelling makes it impossible to fully visalize anything. What do you do?
Send home anti-inflammatories q4-7 days then try again
T/F: Dermatophytosis must be treated wiht both topical and systemic therapy.
True
What are the differential diagnoses for dermatophytosis in dogs? What if the lesions are mostly/only on the face?
Bacterial folliculitis
Demodecosis
Facial: Pemphigus foliceous/erythematosus
What purpose does adjunctive therapy with Cimetidine and Levamizole have?
Immunomodulation
What is the most serious non-neoplasitc disease seen in small animal practice?
Generalised demodecosis
Where does malaseezia dermatitis commonly occur?
Ears and skin folds (lips, ventral neck, axila, interdigital, perianal)
Match the following to deep or superficial pyoderma:
Nasal folliculitits/furunculosis
Acute traumatic pyodermatitis (hot spot)
Puppy pyoderma (Impetigo)
Chin acne/pyoderma
Lick granuloma (acral lick dermatitis)
Superficial: Acute traumatic pyodermatitis (hot spot), Puppy pyoderma (Impetigo)
Deep: Chin acne/pyoderma, Lick granuloma (acral lick dermatitis)
Both/either: Nasal folliculitits/furunculosis
Which dog breeds are predisposed to malassezia dermatitis?
WHWT
Mini poodles
Bassset hounds
GSD
Cocker spaniels
English setters