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
What is Lynxacarus radovsky? Where is it prevalent? What is the classical appearance? How is it diagnosed?
Fur mites (CATS)
Found in: TX, FL, HA, Australia, Brazil
CS: Salt and pepper appearance of fur
Diagnosis: Acetate tape test
Which breeds are predisposed to deep pyoderma? Where does it usually occur in these breeds?
GSD: rump and thoracic regions (also skin blackens and becomes thin)
Bull terriers: hocks, elbows, ventral abdomen, feet
What is the most widely accepted treatment for generalised demodecosis?
Amitraz (q14 days)
Where are lesions usually localized in cats with the atypical eosinophilic granuloma form of EGC? What do the lesions look like?
Skin over bridge of nose, ear pinna: Papular erosion, crusting and depigmentation
Paws: Hyperkeratosis or ulceration
Sarcoptes have a predilication for ____ _____ areas of the body.
Sparsely haired
Malassezia is frequently a secondary invader of skin and ears. What conditions is yeast commonly associated with (4 disorders)?
Allergic dermatitis (fleas, food, inhalant allergens)
Endocrinopathies
Keratinization disorders
Immunosuppression (chronic corticosteroids, neoplasia)
How does dermatophytosis present in dogs? Cats?
Include desciption of alopecia, localization, and specific maladies. For cats include the breed susceptible to generalized infections
Both dogs and cats: Alopecia in face, ears and paws
Dogs- alopecia: peripherally expanding alopecia, crust, follicular papules and pustules
Whole body seborrhea, nodular kerion on nose and distal limbs (M. gypseum, T. mentagraphytes), onychomycosis (nail-bed infection)
Cats-alopecia: irregular or annular, +/- scale
Inflammation rare, can cause miliary dermatitis, eosinophilic plaque
Generalized infection- Persian cats
What antiseptic can be used to treat otitis externa involving resistant pseudomonas (include concentration)
1% silversulfadiazine
(Mix 1.5mL cream with 13.5 ml distilled water, apply BID)
What is the most commonly found bacterium found on a dog with superficial dermatitis?
Staphylococcus
At least how many differrent antihistamines should be tried before you can claim a failure of response? Name a few.
2
Chlorphenamine
Diphenhydramine hydrochloride
Clemastine
Hydroxizine
Terfendine
What causes walking dandruff? Is it zoonotic?
Cheyletiella mites
Yes
Where are lesions for FAD usually located in dogs? Cats?
Dogs: Muzzle, ears, distal limbs, paws (interdigital), axillae, groin region
Cats: Head, face, pinnae, neck
T/F: If a puppy is <6 months old, food allergies are more common that atopy.
True
What is the main cause of otitis externa in dogs? Cats?
Dogs: allergies
Cats: otodectes
What causes Chiggers? Where do they like to hang out? What do they look like?
Trombicula mites
Legs, head, abdomen (in cats inside ears)
Look like paprika (red mites)
What houses the typmpanic cavity?
Tympanic bulla (bony)
Clinical cure of generalized demodecosis precedes parasitological cure. How long must treatment be continued?
Until you a negative skin scrape result for 3 consecutive weeks
How is actinomyces best diagnosed? What are the treatment options (include drugs)?
Dx: Anaerobic culture
Tx:
Best= Surgical debulking
Long-term antibiotics- Clindamycin, pen G, erythromucin, minocyline, amoxycillin
What are the 2 most common causes of eosinophilic granuloma complex in cats? What are the 3 common and 1 uncommon presentations and which are pruritic?
Hypereosinophilic syndrome, Parasites
- Indolent ulcers
- Eosinophilic plaques: intensly pruritic
- Collagenolytic granuloma
Uncommon: Atypical eosinophilic granuloma
What is the pathogenesis of feline acne and what are the clinical signs?
Idiopathic disorder of follicular keratinization
CS: Comodones on chin and lower lip, papules, pustules, furunculosis and scaring
This is a hair sample from a dog with dermatophyosis. What has the fungus caused?
Cuticle degeneration
What is the only way to diagnose food allergic dermatitis? What is the biggest limitation?
Positive response to an elimination diet
Limitation: Owner compliance
Chronic inflammation caused by chronic otitis externa leads to ________ and _________. This causes increased _________ production which prediposes to secondary infections..
Hyperplasia
Hyperkeratosis
Cerumen
What organism is responsible for sarcoptic mange?
Sarcoptes scabei var canis
What can you use to clean a dog’s ears who has a lot of cerumin clogging the ear? What if there is pus?
What can be used after cleaning to dry the area? What if the tympanic membrane is ruptured?
Ceruminolytic: Docusate sodium (emulsift wax and lipids), Propylene glycol
Pus: Warm saline or water; flush with bulb syringe or 3-way stock cock system or automatic system; use curette-loop (less traumatic than swab)
Dry: isopropyl alcohol + acetic acid or salicylic acid or benzoic acid
Alcohol + 2-5% acetic acid if ruptured
What site do you swab and how many swabs should you take to assess otitis externa? What type of sample do you take if you suspect otitis externa caused by mites? What if you’re looking at yeast, inflammatory cells or bacteria?
Site: Horizontal canal
2-3 swabs
Mites: swab to slide with mineral oil, low mag exam
Yeast, inflammatory cells, bacteria: roll sample from swab onto slide, heat fix, Wright’s stain
For keratinocytes and inflammatory cells: Scan at 100x
For bacteria and yeast: Scan at 1000x
What does the topical therapy to treat dermatophytosis entail? (include length of treatment)
Clip around the lesion
Apply topical therapy (Niz shampoo- ketoconazole, creams with sustained/residual activity, spot treatments, rinses (enilconazole)
Continue until you get 2-3 negative (consecutive) weekly cultures
A pruritic dog presents to you with black wax rancid-smelling coming from the ears as well as a red0brown discoloration of the hair around the ears. You also suspect this dog has hypothyroidism. What is probably causing the pruritus?
Malassezia
Which topical cream is effective against gram positive bacteria? Which is effective against Pseudomonas?
Mupirocin
Silver sulfadiazine
You are treating a dog with gram negative, gentamycin resistant otitis externa. What drugs can you use topically? To increase efficacy, what can you do?
Tiracillin
Amikacin
Enrofloxacin
To increase efficacy presoak with TRIS EDTA
What is the most common predisposing cause for deep pyoderma? What secondary immunodeficiencies can predipose to this type of skin infection?
Allergies
Ehrlichia, Distemper (dogs), Retrovirus (cats)
What do Horner’s sydnrome and facial paralysis in a patient with otitis externa indicate?
Concurrent otitis media
You are cleaning the ears of a dog with otitis externa, however you cannot visualize the pars tensa. What should you avoid using? What can you use instead?
Avoid ceruminolytics, cleaning solutions and drying agents
Use normal saline
Definciency of what interleukin is linked to generalized demodecosis?
IL-2
Which 2 things normally prevent food allergens from passing through the intestinal wall?
Innate immune system
IgA antibodies lining the mucous layer
TF: Feline pyoderma is rare.
True
What type of hypersensitivity reaction occurs in contact dermatitis?
type 4
T/F: Contact dermatitis and sarcopitc mange are usually poorly steroid responsive.
True
What drugs are used in the systemic treatment of dermatophytosis? How long is the treatment course?
Griseofluvin
Ketoconazole
Intraconazole
Can be as long as 6-12 months.
How is norcardia diagnosed (3 options)? What are the treatment options (include drugs)
Dx: FNA/cytology, Histopathology, Culture
Tx:
Best= Surgical debulking and drainage
Long-term antibiotics (TMS, ampicillin, erythromucin, minocyline)
A cat comes to you because the owner has noted hair loss on the medial thighs, ventral abdomen and forelimbs. The cat is on a monthy parasiticide and the owner just had a baby. What is the most likely cause of the alopecia?
Psychogenic (Anxiety, self-induced)
Otitis externa is rarely caused by one factor. What can contribute to this infection?
Predisposing factors: stenosis, hair in canals, pendulous pinnae, swimmers ear, overactive glands, polyps, neoplasms
Primary causes: parasites, microbes, atopy, food HS, drug rxns, contact HS, keratinization disorders, glandular disorders, autoimmune dz’s, solar dermatitis
Perpetuating causes: bacteria, yest, topical rxns, foreign bodies, epidermal hyperplasia, hyperkeratosis, dermal edema/fibrosis, lumen stenosis, cartilage mineralization, typanic membrane changes, middle ear disease
What is the MOA for amitraz? If you use too much, what do you do?
A-adrenergic agonist, MAO inhibitor, and prostaglandin synthesis inhibitor
Give atipamazole or yohimbine to reverse
You notice a well-circumscribed, proliferative inflammatory lesion with a dish-shaped central ulcer on the upper lip of a cat. It is not painful nor itchy. What are 2 possible causes?
EGC
Calicivirus
Does every food antigen result in an acquired immune response? Why or why not?
No
T-cells need co-stimulatory factors for activation which do not get activated unless the allergen is a “threat”
What bacterium causes Impetigo?
Staphylococcus
What are the 3 forms of the Collagenolytic granuloma presentation of EGC in cats?
Linear
Pharyngeal
Chin
What gram postivie anerobic bacterium causes infection following trauma/penetrating wounds which can create draining tracts that can take years to form? What are the clinical clinical signs?
Actinomyces
SQ abscesses, draining tracts, exudates (thick, yellow-gray, hemorrhagic, foul-smelling, +/- sulfur granules)
T/F: Cats tend to have adverse food reactions against beef, dairy, wheat, chicken eggs, lamb and soy. Dogs tend to have adverse ractions to beef, dairy and fish.
False, opposite
Dogs: Beef, dairy, wheat, chicken eggs, lamb, soy
Cats: Beef, dairy, fish
T?F: Generalized demodecosis is hereditary.
True (don’t breed)
What type of surface pyoderma commonly affects the commisures of the lips?
Mucocutaneous pyoderma
How do you diagnose hookworm dermatitis?
Fecal floatation
Match a term under A with something from B:
A:
Food allergy/Hypersensititivity
Dietary Intolerance
Food anaphylaxis
B:
Systemic involvement
No immune respose
Immune response
Food allergy/HS: immune resposne
Dietary Intolerance: no immune response
Food anaphylaxis: systemic involvement
What is “glue ear” and which breed is predisposed to it? How is it treated?
Primary secretory otitis media (PSOM)
CKCS (King Charles)
Tx: Myringotomy and middle ear flush
Which presentation of EGC in cats is associated with allergies?
Eosinophilic plaque
Malassezia can cause paronychia. What is this?
Soft tissue infection around the claw/nail (claw fold)
How is feline acne treated? What about refractory cases?
Treat secondary infection (systemically or topically)
Clip and clean area with human acne preparation (Benzoyl peroxide)
Refractory: Vit A
What is the best way to diagnose deep pyoderma?
Bacterial culture and antibiogram
(C&S)
What are the 2 parts of the tympanic membrane? Bulging of which part indicated material in the tympanic bulla?
Pars flaccida
Pars tensa (if bulging=material in bulla)
What are the 2 antigen types that most commonly cause food allergies? What is the most common specific antigen?
Proteins
Glycoproteins
Specifically: Beef protein
What ectoparasites, aside from fleas, cause pruritus in cats?
Notoedris
Demodex gatoi
Fur mites
Cheyletiella
Ectopic ear mites
The middle ear starts at the _____ _____ and consists of the _____ cavity, ____, auditory ______, and ______ tube.
Tympanic membrane
Tympanic
Bulla
Ossicles
Eustachian
The middle ear starts at the tympanic membrane, and consists of the tympanic cavity, bulla, auditory ossicles**, and **eustachian tube.
T/F: A deep skin scape is used for demodex while a superficial skin scape is used for sarcoptes.
True
T/F: If mites are detemrined to be the cause of otitis externa in a dog, all dogs and cats in the household need to be treated.
True
Cell immunity is mediated through ___ lymphocyte activation.
Humoral immunity is mediated through ___ lymphocyte activation as well as _____ and _____.
Cell: T
Humoral: B, plasma cells, immunoglobulins
What are the topical and systemic treatment options for malassezia? When would you use one over the other?
Topical:
Anti-yeast shampoo (ketoconazole, miconazole, selenium sulfide)
q2-3 weeks
Anti-yeast rise (enilconazole)
Systemic:
Keto or Intraconazole until clinical cure
Always use TOPICAL FIRST if possible, systemic if infecion is extensive and topical isn’t working.
There are side-effects that limit the use of -azole group drugs, these include anorexia, vomiting, diarrhea, and HEPATOTOXICITY.
What is the pinnal pedal reflex and which cause of pruritis does a positive reflex suggest?
Touch ear = Shake leg
Sarcoptic mange
Why is there usually an underlying disorder if a dog or cat comes down with deep pyoderma?
Healthy skin is resillient to infection
(Physical defense- compact stratum corneum, lipid emulsion and intracellular cement; Immune system, and microbial defense)
How can you diagnose malassezia (include values)?
Cytology: skin scrape, scotch tape, cotton swab, direct impression
Must have >2 per HPF (1000x)
Which topical product is used for pyoderma with dry seborrhea? Which would be used for pyoderma with oily seborrhea or comodones?
Include the strength/concentration
Chlorhexidine <0.5%
Benzoyl peroxide 1-5%
