Week 7 - Dermatology Flashcards
What is the etiology of a FOOD ALLERGY?
-Uncertain, but publications have supported both cell- and antibody-mediated mechanisms
-immunologically-based reaction to food
-In adult dogs, most offending diets fed for >2 years
-theorized that most food allergens are proteins
What is FOOD INTOLERANCE?
-adverse reaction to food that does not have
an immunologic basis, including food poisoning (caused by the direct action of a toxin)
What’s the signalment for CAFR/cutaneous adverse food reaction)?
-Age at onset: 4 months to 12.5 years
-Age of onset: 33% of dogs are 1 year of age or less
-Breeds: retrievers, terriers
CS of CAFR/cutaneous adverse food reaction? in dogs
DOGS
-Pruritus (usually directed at feet or ears)
–Generalized / pododermatitis
–Otitis externa
-Scaling, papules, erythema
-most often manifest as bacterial skin infections
-signs similar to atopic dermatitis
GENERAL
-non-seasonal pruritus which is usually generalized
-GI signs
most common primary dermatologic lesions: -papules
-erythema
-common secondary lesions are epidermal collarettes (usually indicating a pyoderma)
-pyotraumatic dermatitis (‘hot
spots’)
-hyperpigmentation
-seborrhea
-idiopathic onychodystrophy (misshapen,
splitting claws)
-Cocker Spaniels - idiopathic seborrhea
CS of CAFR/cutaneous adverse food reaction? in cats
-Pruritus, alopecia
–face/neck in 40-50%
-Papules, miliary dermatitis (papules with crust)
-Eosinophilic granuloma complex
-Self-induced alopecia
What GI signs can you see with CAFR/cutaneous adverse food reactions? dogs and cats
What other CS are there with CAFR?
-Diarrhea, vomiting: concurrent in only 10% of cases
-GI plus pruritus in cats = food allergy
-Mild colitis (dogs)
-Lymphocytic-plasmacytic colitis (cats, cheetahs)
-Neurologic
–Malaise
–epilepsy (dogs)
-Respiratory
–Asthma-like signs
Common Food Allergens in North America
Dogs
-beef, cow’s milk, chicken, chicken, eggs, corn, soy, wheat
-Most allergic to <3 allergens
Cats
-Fish, milk, milk products, beef
–
Dogs: beef, dairy, wheat, lamb, egg, chicken
Cats: beef, dairy, fish, poultry, rabbit
What are food antigens?
- Glycoproteins with a molecular weight of 10 - 70 KDaltons
- Typically attributed to “protein sources”
- Found in meat, legumes, tubers, grains, etc.
What should you consider when choosing an Elimination Diet?
-Diet History! Every patient, every visit
-Ingredients that are NOVEL to this patient
What should a diet history contain?
- Ingredient lists of all prior diets/treats
–Supplements/meds (and how given!) - Meat or meat by-products: bovine, ovine, porcine, caprine
- Poultry, meat, fish, animal
What are elimination diet options?
- Home-cooked limited ingredient combinations (ensure balanced if long term)
- Commercial hydrolyzed diets
-Average molecular weight <10-12 kDaltons - Commercial limited/uncommon antigen diets
-Rabbit, venison, duck, fish, kangaroo, alligator
-All of these are found OTC!
novel or hydrolyzed approach, homemade or commercial
What is the goal of elimination diets?
- Goal: limited number of uncommon (and ideally
known to be novel) ingredients - Many OTC diets have an extensive ingredient list (ie they are not limited diets despite the claim!)
-include more common ingredients
-More difficult to troubleshoot - OTC not ideal for elimination diets or for maintenance of patients with confirmed food allergy
-i.e. Don’t use for diagnosis or treatment
What are veterinary therapeutic diets?
*Veterinary diets are successful for diagnosis
food allergy
-prescription diets
- No one diet works for every animal!
–Monitor response
–Some evidence hydrolyzed diets more effective
What are other sources of antigens?
- Treats
- Toys
- Toothpaste
- Supplements and medications
–Gelcaps made from gelatin (pork or beef)
–Flavoring
–How meds given
How long should an elimination trial last?
*Should last at least 8 weeks
->90% dogs and cat with food allergy show complete remission
- Challenge process
-Reintroducing the original diet can help confirm food allergy (vs. seasonal atopy that happened to resolve for example)
If a diagnosis is confirmed for food allergy via an elimination trial, then:
- Continue to feed test diet, if balanced
OR
*While back on test diet, challenge animal with
most common allergens (that are also present
in individual diet history), 1-2 weeks each – to figure out what they’re actually allergic to
Why are topicals important?
■ Can be sole or adjunctive treatments for numerous skin conditions
■ Relatively cheap (usually) compared to oral medications
■ Direct delivery of a specific ingredient to the skin surface
■ Because owners will ask you “How do you feel about (insert random topical product here)? quite often
What if oral antibiotics are not an option?
■ Some skin infections don’t give you many (or any) systemic antibiotic options
■ Topicals are usually your best option for resistant skin infections
What are the types of topical products?
§ Shampoos
§ Conditioners
§ Rinses/dips
§ Wipes
§ Mousses
§ Sprays
§ Powders
§ Lotions
§ Creams
§ Ointments
§ Gels
Shampoos can be used as topical treatments
■ Medicated shampoos require minimum contact time of 10 minutes
■ Rinse off with cool water and towel dry
■ During bathing, only wash hair in direction of hair growth
■ Depending on the product and purpose, can be used daily to every other week
– More frequent for treatment of pyoderma
Conditioners can be used as topical treatments
■ Conditioners contain cationic surfactants > bind to damaged, negatively-charged hair shafts > reduce static electricity, flatten hair shaft cuticles, increase light reflectance, etc.
■ Depending on agents, replaces oils lost by bathing with medicated shampoo
Risnes/dips can be used as topical treatments
■ Concentrated solutions or powders mixed with water
■ Poured, sponged or sprayed onto animals - usually for full-body coverage
■ Deliver various agents – usually antiparasitic, antifungal, antibacterial, and/or antipruritic
■ Usually not absorbed well – mainly surface effect
■ Do NOT rinse off after use (as such, “dip” is a better term to use)
Sprays can be used as topical treatments
■ Can be aerosol or pump-based
■ Can carry a variety of different
agents
■ Easy to use – least time consuming
■ Best for focal areas, but can provide
full-body coverage
- May be alcohol-based – can sting
- Noise/sensation may frighten pets
- Not ideal for well-haired areas
- Do NOT rinse off after use
Powers can be used as topical treatments
■ No longer commonly used in veterinary medicine
– Except for a few large animal antiparasitic products
■ Antiseptic powders useful for focal, moist lesions (such as ”hot spots” or acute moist dermatitis)
■ Neo-Predef with tetracaine powder
– Neomycin, isoflupredone, and tetracaine
■ Powders create thick, messy barriers if not removed regularly
What are some ACTIVE INGREDIENTS/AGENTS
Antibacterial
Antifungal
Antiparasitic
Keratomodulating (antiseborrheic)
Antipruritic
Anti-inflammatory
Moisturizing
AND MORE
What do antibacterial agents do?
-treat pathogenic bacteria
- Chlorhexidine
- Benzoyl peroxide
- Ethyl lactate
- Mupirocin
- Silver sulfadiazine
- Combo antibiotic products
- Sodium hypochlorite (bleach)
- Povidone-iodine
- Coal tar
- Boric acid
- Acetic acid
What do anti fungal agents do?
-Treat pathogenic fungal organisms
- Imidazoles
- Nystatin
- Thiabendazole
- Terbinafine
- Selenium sulfide
■ Typically used for Malassezia dermatitis and
dermatophytosis
– Not all agents active against both
■ Some antibacterial agents also have antifungal
properties
– Chlorhexidine, povidone-iodine, silver
sulfadiazine, etc.
What do antiparasitics do?
-Treat skin parasites
■ Lime Sulfur
■ Amitraz
■ Imidacloprid
■ Selamectin
What is a Keratomodulating Agent?
-KERATOLYTIC (remove excess scale (dandruff))
* Decrease cohesion between keratinocytes, increasing desquamation
-KERATOPLASTIC (reduce scale production)
* Decrease mitotic rates of basal keratinocytes, normalizing epidermal turnover rate
-Some keratomodulating agents are “anti-seborrheic”
* Anti-seborrheic agents - “degreasing” by inhibiting/reducing sebum production and clearing glandular ducts
What is the epidermal average turnover rate?
~21 days
What do anti-inflammatory agents do?
-reduce inflammation
-usually think steroids, but other agents have anti-inflammatory properties too
- Higher the potency/concentration/volume/frequency of application of the topical steroid, higher the risk of side effects
- Side effects can be local or systemic (iatrogenic hyperadrenocorticism if excessive percutaneous absorption or ingested)
- Skin atrophy with prominent dermal vasculature
- Scaling
- Alopecia
- Comedones (blackheads)
- Milia (whiteheads)
- Pyoderma
- Demodicosis
What do moisturizing agents do?
-Increase epidermal hydration
-moisturizers decrease transepidermal water loss (TEWL) by replenishing intercellular lipids (“mortar”, “cement”) and increasing corneocyte water retention capacity
- EMOLLIENTS – usually lipid-based
-improve skin barrier function, cell membrane fluidity, and keratinocyte cell-signaling - Examples: ceramides, essential fatty acids, cholesterol, etc.
- HUMECTANTS – non-oily, hygroscopic agents
-Bind to corneocytes and attract water (from dermis and/or environment)
-Examples: glycerin, sorbitol, urea, propylene glycol, lactic acid, amino acids, etc.
What do astringent agents do?
-They’re drying agents
■ Precipitate proteins on skin surface
■ Decrease exudation by constricting superficial blood vessels
■ Useful in exudative dermatoses
■ Generally do not penetrate deeply
What does Chlorhexidine do?
Antibacterial, antifungal* (at 3% or greater)
■ Antibacterial at any concentration
■ *Antifungal (anti-yeast) at 3% concentration or greater
– Not effective for dermatophytes as sole topical agent
■ Fast-acting (efficacy within 20-30 seconds) and residual activity (~48 hours)
■ Indications: superficial pyoderma, Malassezia dermatitis
– Often used once daily for treatment, then once to twice weekly for
maintenance
■ 4% or less usually non-irritating
■ Can delay healing of granulation tissue
■ Toxic to the cornea
– Use very dilute products
What is Benzoyl Peroxide?
-Antibacterial, keratolytic, degreasing
■ Breaks down keratin – unclogs hair follicles and allows better sebum flow
■ May have some residual activity (up to 48 hours)
■ Comes in gel (human products - range from 2.5 - 10%) and shampoo (2.5%)
– Usually applied once to twice daily
What is Ethyl Lactate?
-antibacterial, astringent
-■ Breaks down to lactic acid and ethanol (both antibacterial)
■ Common veterinary product = BioSeb mousse and shampoo (10% ethyllactate)
– Usually well-tolerated – good option if not tolerating chlorhexidine-based products
– Low residual activity
■ Indications: superficial pyoderma
What is sodium hypochlorite/bleach used for?
-Antibacterial, antifungal
■ Action is thought to be due to liberation of
hypochlorous acid
■ Bactericidal, fungicidal, sporicidal, & virucidal
– Most commonly used for generalized,
resistant superficial pyoderma (MRSP)
■ Standard bleach products between 5.25% - 8.25% - dilute 1:10 to 1:20 with water
– SPOT-TEST – ensure no severe irritation
prior to soaking the pet
■ Presence of organic debris reduces
antimicrobial activity
■ Shampoos with sodium hypochlorite
What is Mupirocin?
-topical antibiotic
■ Antibiotic in its own class
– Unique MOA limits cross-resistance with other antibiotics
■ Mostly gram-positive activity
– Very minimal gram-negative activity
■ Excellent for (focal) resistant Staph pyoderma
- Available as brand-name and generic
ointment/cream (2%) - Great for focal lesions
- Usually applied twice daily
- Excellent skin penetration
What is Silver sulfadiazine (SSD)?
-Antibacterial, antifungal
-■ Sulfa-derived antibiotic with silver
– Damages cell membrane and cell walls
■ Extensive broad-spectrum activity
– Gram+ and gram- bacteria, yeast
– Very useful for Pseudomonas aeruginosa infections (0.1 – 1% concentrations)
- May enhance re-epithelialization, but can inhibit granulation and wound contracture
- Commonly used for burns and shallow wounds
- Avoid in dogs with potential sulfa-drug sensitivities
- Available in skin cream and otic medication
- Usually applied once to twice daily
What are Imidazoles used for?
-Antifungal
-■ impair fungal cell membranes
■ Examples: Miconazole, Ketoconazole, Clotrimazole, Climbazole, Posaconazole
■ Synergistic with chlorhexidine
■ Formulated in many otic products, shampoos, mousses, etc.
■ Indications: Dermatophytosis, Malassezia dermatitis
What is Lime Sulfur used for?
-Antifungal, Antiparasitic, keratolytic, keratoplastic
-DOES NOT treat demoted or fleas
■ Mixture of calcium and sulfur
■ Safe to use in basically any pet
■ Available in rinses/dips
■ Indications: dermatophytosis (most common), but can also be used for most ectoparasites
- For dermatophytosis:
- Good option in cat shelters
- Used every 5-7 days (need to bathe first)
- Do NOT rinse off after use
CAUTION/CONS:
■ Stains skin, hair, fabric, any porous surface (jewelry, countertops, etc.) YELLOW-GREEN > Wear gloves, take off jewelry, don’t let pet roam
■ Can cause skin irritation and excessive dryness
■ Can cause mucous membrane ulcers
– Avoid the eyes and mouth!
– Prevent grooming post-rinse!
■ Smells terrible – use only in well-ventilated areas
What is Tris-EDTA used for?
-Antibacterial, antifungal, anti-biofilm
■ De-stabilizes bacterial/yeast cell walls and biofilms by chelating metal ions
■ Alkalinizing (pH ~ 8) – potentiates efficacy of several antibiotics
■ Synergistic with chlorhexidine
- Inhibits ulcerative bacterial enzymes
- Considered safe for the middle ear
- Used as buffer in many ear cleaners, shampoos, sprays, etc.
What is Colloidal Oatmeal used for?
-Antipruritic, humectant, mildly anti-inflammatory
■ Contains high concentrations of starches and beta-glucan (polysaccharides) > bind to corneocytes and retain water (humectant)
■ Inhibit production of pro-inflammatory cytokines (anti-inflammatory, antioxidant, antipruritic)
■ Present in several veterinary shampoos and sprays
■ Indications: maintenance topical for allergic dermatitis; seborrhea sicca
As topicals, what do Essential Fatty Acids and Ceramides do?
-Emollients, anti-inflammatory
■ Essential fatty acids (EFAs)
-Improve skin barrier
-Examples: omega-6’s (gamma-linoleic acid, etc.) and omega-3’s (EPA, DHA, etc.)
■ Ceramides – specific form of fatty acids
– Make up 50% of the corneocyte lipid envelope – vital for healthy skin barrier
– Phytosphingosine, ophytrium - most common ceramide in topical products
As a topical, what does Salicylic acid do?
Keratolytic, keratoplastic, humectant, astringent, bacteriostatic, ceruminolytic
■ Increases ability of corneocytes to absorb water (humectant) while drying out
the skin surface (astringent)
■ Promotes desquamation (keratolytic)
■ Indications: excessive scale
– May be less drying than chlorhexidine
What flea has a host preference for a cat?
Ctenocephalides felis felis
- Commonly called Cat Flea
- The MOST common type of flea in small
animals
-92% prevalence in dogs, 97% prevalence in
cats - Found worldwide
- Can live on a wide range of mammals
What flea has host preference for a dog?
Ctenocephalides canis
- Dog Flea
- Less common in dogs than C. felis
- May see more C. canis in kenneled working dogs
- Wide geographic distribution
- Has a similar life cycle to C. felis
- Treat the same way you would C. felis
ECHIDNOPHAGA GALLINACEA is a flea with a preference for ____
POULTRY and DOGS
- Found most commonly on domestic
poultry - Can also be found on other species
- Found primarily in tropical regions
- Female fleas burrow into areas of bare
skin and attach themselves
What’s the life cycle of a flea?
Adult
Egg
First stage larva
Second stage larva
Third stage larva
Pupa
Adult
Female starts laying eggs within 24 hours of
her first blood meal.
- Can lay 40-50 eggs per day
- Eggs are not sticky
- Fall off host into environment
- Development is dependent on ambient
temperature & relative humidity - Usually hatch within 2-5 days
How many larva stages are there?
- 3 stages
- Molt in between stages
- Each stage lasts 5-11 days
- Feed on organic matter, flea feces and dried blood
- Negatively phototactic, positively geotactic
–away from light, likes gravity - Most likely to be found in carpet, cracks in floor, under baseboards, etc
75 adult fleas can ingest ____ml of blood/day
1ml
What is FAD?
flea allergic dermatitis
- Hypersensitivity to flea saliva, must have flea bite to initiate reaction
- More hypersensitive animal, fewer bites needed for reaction
- May not see fleas or flea dirt
- Important consider as part of allergy management
What is Canine FAD?
- Any age, breed can be affected
- Seasonal or nonseasonal
- Clinical signs noted on caudal half
- pruritus, erythema, papules, alopecia
- May have secondary pyoderma
What is Feline FAD?
- Any age, any breed can be affected
- Seasonal or nonseasonal
- Clinical signs may be anywhere
- Especially head & neck
- Pruritus, erythema, alopecia, plaques,
miliary dermatitis - Cannot distinguish between allergic dermatitis based on location of itch
How do you DIAGNOSE fleas?
- History
- Flea Comb
-If you find flea dirt, there are adults
-Collect on paper towel and dampen- turns
red/brown - Location of itch
-Often focused at tail head - Treatment Trial
How do you TREAT fleas?
- Control the life cycle!
- All animals must be on excellent flea
control - May have concurrent food or
environmental allergies
When treating fleas, you can use INSECT GROWTH REGULATORS
-FOCUS ON: preventing larvae or pupae from becoming adults
-2 types
–Juvenile Hormone Analog
–Chitin Synthesis Inhibitor
- Methoprene - Frontline Plus®
- Pyriproxyfen - Nylar®, Advantage II®,
Advantix II®, Vectra 3D - Lufenuron - Program®/Sentinel®, Novartis
When treating fleas, you can use ADULTICIDES
- Kills adults, prevent them from further laying eggs
–Kill female within 24-48 hours - By preventing females from laying eggs, you disrupt the life cycle
When treating fleas you can use TOPICAL PRODUCTS
- The more the animal gets wet, the less effective
any topical - Most topicals have about the same speed of kill
- Avoid pyrethroid/pyrethrin products in felids
–Toxic - can cause severe neurologic signs & death
–Ex: permethrin
–Exception: Flumethrin (ie in Seresto collars)
SELAMECTIN+SAROLANER (REVOLUTION PLUS®) – a topical for fleas
- Selamectin activates glutamate gated
chloride channels - Kills flea adults, Otodectes, Sarcoptes
Notoedres, Cheyletiella, internal parasites,
some ticks - > 8 weeks of age
- Selamectin alone
- Safe for rodents, rabbits,
FIPRONIL (FRONTLINE ®) – a topical for fleas
- Binds GABA receptors & blocks transfer of chloride ions
- Uncontrolled stimulation of CNS & death
- Kills fleas, ticks and lice
- Frontline Plus also has s-Methoprene
- > 8 weeks of age
- Do NOT use in rabbits or hedgehogs
IMIDACLOPRID WITH MOXIDECTIN (ADVANTAGE-MULTI®; BAYER) - a topical for fleas
- Binds post synaptic nicotinic receptor-
blocks impulse transmission - Kills fleas, Heartworm, intestinal parasites,
and Otodectes cynotis (in cats) - Canine and feline demodicosis
- Useful with concurrent CNS disease
- > 7 weeks of age
- Don’t use in birds – moxidectin is ok but imidacloprid is toxic in avians
FLURALANER (BRAVECTOTM MERCK) - topical for fleas
- Bravecto topical for cats
- Can also use canine oral
Bravecto in cats, but must
change dose - Also lasts 3 months as in dogs
- Well tolerated
- > 6 months of age
- Now have Bravecto Plus
When treating fleas, you can use ORAL products
- Are quicker to kill fleas
- Often easier to administer
- Many should be given with a meal
- Often flavored
Isoxazolines are used as oral products to treat fleas
- Inhibits GABA gated chloride ion channels
-Blocks pre and post synaptic transfer of ions - Results in prolonged hyperexcitation and death of insects and acarines
- CNS signs have been reported (ataxia, tremors, seizures)
-Resolve within 24 hours
AFOXOLANER (NEXGARDTM MERIAL) is an isoxazoline - used as an oral product to treat fleas
- Oral chewable
- Kills fleas and ticks
- Effective (but not yet approved) against Demodex and scabies
- > 8 weeks of age
- Soy protein
- Avoid in animals with a history of seizures
FLURALANER (BRAVECTOTM MERCK) is an isoxazoline - used as an oral product to treat fleas
- Oral chewable or topical
- Kills fleas and ticks
- Lone Star Tick up to 8 weeks
- Effective (but not yet approved) against Demodex and scabies
- > 6 months of age*
- Hydrolyzed pork
- Avoid in animals with a history of seizures
SAROLANER (SIMPARICATM,ZOETIS) is an isoxazoline - used as an oral product to treat fleas
- Oral chew for fleas and ticks
- Effective (but not yet approved) against scabies,
Demodex, and Otodectes cynotis - > 6 months
- Chicken liver flavor
- Simparica Trio is now available – added heartworm
preventative - Avoid in animals with seizures
- Revolution Plus for cats now contains sarolaner
LOTILANER (CREDELIO®) - is an isoxazoline - used as an oral product to treat fleas
- Oral chewable
- Kills fleas and ticks
- Effective (but not yet approved) against Demodex and scabies
- > 8 weeks of age
- Pork liver and soy
- Avoid in animals with a history of seizures
SPINOSAD (COMFORTISTM, ELANCO) - an oral product to treat fleas
NOT Isoxazoline
- Activates nicotinic acetylcholine receptors
- Once monthly chewable
- > 8 weeks
- Pork liver and soy
- Do not give with daily ivermectin
MILBEMYCIN/SPINOSAD (TRIFEXIS®, ELANCO) - an oral product to treat fleas
NOT Isoxazoline
- Milbemycin binds glutamate gated chloride
channels - Kills heartworm, fleas, intestinal worms
- Once monthly chewable
- > 8 weeks of age
- Pork and soy
- Avoid giving in combination with ivermectin
NITENPYRAM (CAPSTARTM) - oral product to treat fleas
- Acts on postsynaptic nicotinic acetylcholine receptor
- Paralysis, hyperexcitability and death
- kills adult fleas; 100 % within 6
hours - Can be given orally every 24-72 hours
- > 4 weeks of age
What environmental treatment would you do for fleas?
- Vacuum and throw bag away
- Avoid steam cleaning carpet or cloth
-Kills larva but raises humidity for future generations - If severe infestation, hire professional exterminators
- “Flea bombs” are of little benefit
- By treating the animal, you will help treat the
environment
