Transcript DipaDermatology - Dr. Brahmbhatt`s Class Handouts

LEARN TO ADAPT
“Change is inevitable-except from a
vending machine”
-Robert C. Gallagher
DIAGRAM – SKIN LAYERS
Differences: Epidermis, apocrine glands (seal outer surface, phermones)
compound hair
Apocrine vs. Sebaceous
• Apocrine
– ~ Sweat glands
• Specialized forms in
eyelids, external ear canal
– Hair follicle complex
– Anal sacs
– Sympathetic NS
• Sebaceous
– Hair follicles
– Secrete sebum (oily)
– Large glands
• Dog: dorsum of tail,
Mucocutaneous junction
• Cat: dorsum of tail, on lip
margins and under chin
Skin
• Protects from physical, chemical and
microbiological injury
• Sensory organ: pain, heat, cold, touch
• Storage: Electrolytes, water, proteins, fats and
carbohydrates, activates Vit D by sunlight
• Epidermis
• Dermis
• Hypodermis/ subcuticular: Stores fat for
insulation and energy
Dermatology-skin layers
Basic Anatomy & Physiology
• The skin is made up of three
layers:
– Epidermis (the most
superficial layer that contains
cells, but not blood vessels)
– Dermis (the middle layer that
is composed of blood and
lymph vessels, nerve fibers,
and the accessory organs of
skin such as glands and hair
follicles)
– Hypodermis (subcutaneous the deepest layer that is
composed of connective
tissue) - fat
Skin - Function
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Enclosing barrier: Water and electrolyte loss
Environment protection
Temperature regulation
Sensory perception: touch, temp. and pain
Motion and shape
Antimicrobial and antifungal
Blood pressure control: peripheral vascular bed
Secretion: apocrine and sebaceous glands
Adnexa: hair, nails, hooves, horny layer – epidermis
Storage: Electrolyte, H2O, Vit., fat, protein, Carbs and other..
Pigmentation: color and sun protection
Excretion: some
Sun > activate vit D > normal Ca absorption
Definitions
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Dermatology: study of diseases of the skin
Dermatosis: skin disease
Alopecia: hairloss
Seborrhea: Excessive secretion of sebum (oily secretion of
the sebaceous glands composed of fat and epithelial debris)
Scale: Flakes of stratum corneum on the skin surface or
hair coat; various colors
Erythema: increased redness
Collarette: circular arrangement of scale with central area
of hyperpigmentation
Crust: accumulation of dead cells and exudate on skin
surface
Epidermal Collarette
• Most likely bacterial
infection
• Less commonly fungal
infection, immunemediated skin disease,
insect-bite reaction, or
contact hypersensitivity
Scale of loose keratin flakes or "peeling" keratin arranged in a circle
Definitions
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Ectoparasites: external parasites
Skin Scraping: method of examining skin for parasites
Dermatophyte: fungi that grow on the skin
Dermatomycosis: fungal skin infection not involving pathogens
below
Dermatophytosis (ringworm): a skin infection with
keratinophilic fungi (e.g. Microsporum; Trichophyton,
Epidermophyton)
Pyoderma: Bacterial infection of skin
• Superficial
• Deep
Fungal culture – lab test used to grow dermatophytes for
identification
Bacterial culture and sensitivity: lab test used to grow and
identify bacteria from lesions and determine antibiotic sensitivity
Definitions
• Impetigo (not intertigo: skin fold pyoderma): Superficial
bacterial skin infection seen in young dogs “puppy pyoderma”
(staph)
• Acne: Pores clogged with oil forming “blackheads”, esp chin
• Lesion: area of altered skin
• Rash: wide spread eruption of lesions
• Hyperpigmentation: increased pigmentation (melanin) of
skin (epidermal/dermal)
• Lichenification: Thickening and hardening of skin
characterized by exaggerated superficial skin markings.
• Cyst: Fluctuant nodule; walled off, fluid filled nodule
Hyperpigmentation:
Dff: endocrine dermatoses,
secondary postinflammatory
change due to a variety of
skin diseases.
Lichenification:
Dff: All chronic and
pruritic skin diseases
Definitions
• Macule: A focal, circumscribed, nonpalpable change in
color <1 cm (when it is larger, it is termed a patch).
• Papule: small, circumscribed, solid elevated lesion of
the skin ~ 1cm
• Wheal: A sharply circumscribed, raised, edematous
lesion that appears and disappears within minutes to
hours
• Pustule: a small, elevated, circumscribed, puscontaining lesion of the skin within the epidermis.
• Abscess: localized collection of pus; larger than a
pustule
• Cellulitis: swollen, tender area of skin with bacterial
infection; can develop into an abscess
Macule: Vitiligo,
discoid lupus erythematosus,
uveodermatologic syndrome,
mucocutaneous pyoderma.
Papule: Bacterial folliculitis,
demodicosis, fungal folliculitis,
flea-bite and
mosquito-bite hypersensitivity,
scabies, contact allergy,
autoimmune skin disease,
drug eruption
Pustule: Bacterial infection,
fungal infection,
autoimmune skin disease
Urticaria, insect bites,
other hypersensitivities,
drug eruption
Definitions
• Granulation tissue: new
tissue in a healing wound;
consists of connective tissue
and capillaries
• Erosion: loss of skin
surface; shallow, moist,
crusted does not penetrate
basement membrane
• Ulcer: loss of the epidermis
resulting in exposure of
dermis
• Comedone: dilated hair
follicle blocked with sebum
and other cellular debris
Various skin diseases associated
with self trauma such as infections
or allergies
Various skin diseases associated
with trauma such as
infections and allergies, also
immune-mediated diseases.
Seborrhea
• Seborrhea is characterized
by abnormal flaking or
scaling of the epidermis and
may be accompanied by
increased oil production
(seborrhea oleasa) or not
(seborrhea sicca)
– Accelerated skin cell
turn-over with or without
excessive sebum
production.
Seborrhea
• Normal skin cell turnover – 3
weeks
• Time period is shortened in
seborrhea. Abnormal
keratinization
– Accelerated (few days) => build up
of keratin (dead cells) => flakes
• Altered sebaceous gland
secretions
– Normal secretion of oil in or near
hair follicles enriches skin
Seborrhea
Seborrhea
• Causes
– Primary: hereditary as in Amer. Cocker Spaniel, Eng.
Springer Spaniel, Westies, Basset Hounds
– Secondary: disease/injury to skin from other causes
• Allergies, parasites, nutritional disorders, immune-mediated, endocrine
disorders (hypothyroidism)
• Types
– Seborrhea sicca: dry, only scaliness
– Seborrhea oleosa: oily + scales
Seborrhea sicca
DRY and SCALY
Seborrhea oleosa
Keratolytics
• Keratolytics are an important group of
antiseborrheics
– Keratolytics remove excess keratin and promote loosening
of the outer layers of the epidermis
– Keratolytics break down the protein structure of the keratin
layer, permitting easier removal of this material
– Found in medicated shampoos to help in treatment of
seborrhea
Seborrhea – Treatment
• Medicated shampoos
– Sicca: Sulfur (keratolytic, antipruritic,
antibacterial, antifungal, antiparasitic);
Salicyclic acid (KL, AP, AB)
– Oleaso: Coal tar: degreaser, KL;
BENZOYL PEROXIDE: Also for
Moist dermatitis, pyoderma, stud tail
– Conditioners
Seborrhea – Treatment
• Clip hair so shampoo
can penetrate
• If secondary, treat
underlying cause
– Antifungal and/or
antibacterial meds
• Omega-3 fatty acid
supplements
– Anti-inflammatory, antipruritic properties
Seborrheic Fungal Dermatitis
• Malassezia species
• Some commensal on skin (normal)
• Cause infection when skin surface
altered/abnormal or immunosuppressed
• Diagnosed by cytology (stained slides)
– Skin impressions:
Samples can be obtained via tape prep or impression smear
• Tx:
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2% miconazole/2% chlorhexidine shampoo
Selenium sulphide
Other Antifungals: ketoconazole, clotrimazole, miconazole
Oral ketoconazole x 3+ weeks (not approved in dogs and cats)
Seborrheic
Fungal
Dermatitis
Pyodermas
• Definition: Bacterial infection of skin, superficial or
deep; Primary or secondary
- Occurs when:
- skin surface broken
- skin macerated by chronic exposure to moisture
- Normal bacteria altered
- Circulation impaired
- Immunocompetence impaired (aka
immunosuppressed)
• Superficial- Lesion usually involve superficial
epidermis and heal w/o scarring, short duration, rarely
ill
Pyoderma - Causes
- Dogs - Staph intermedius
- Cats – Pasteurella multocida
- Deep pyodermas – gram-negative organisms (E. coli,
proteus sp, pseudomonas sp)
- Risk factors
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Allergies
Fungal infections
Endocrine diseases
Immune incompetence
Seborrhea
Conformation – ex: skin folds
Trauma
Foreign body
Pyoderma
- Superficial – commonly the trunk
- Deep – chin, nose, pressure points, feet, generalized,
skin folds
- PE may show: papules, pustules, crusts, epidermal
collarettes, circular erythematous or hyperpigmented
spots, alopecia, scaling, lichenification, abscess,
cellulitis, etc..
Pyoderma
EPIDERMAL COLLARETTES ‘PEELING EDGE’
PYODERMA
ERYTHEMA, PUSTULES
Superfical Pyodermas
• Acute Moist Dermatitis, Superficial pyotraumatic
dermatitis (“Hot Spots”)
– Clinical Signs:
• red, moist, painful areas, oozing
• Common in thick coated dogs (Labs, Newfoundlands, Ger. Shepherds,
Chows)
• Usually in hot moist summer months
• Hair loss, very pruritic
• Develops very fast
– Dx: visual inspection of affected area
– TX
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Clip hair around lesion until skin normal
Cleanse skin with medicated shampoo
Topical Ab’s/steroid creams or sprays (ex: Betagen Spray)
Treat original disease (fleas, allergies)
Systemic steroids, Abs
Superficial Pyodermas
– Client Info
• Gentle cleansing BID
• Owner should wash hands after treatment
• E-collar may be necessary
Superficial Pyoderma: “Hot spot”
Superficial Pyoderma: “Hot
Spot”
Superficial pyoderma: “Hot
Spot”
Superficial Pyodermas
• Impetigo (aka superficial pustular dermatitis)
– Signalment: young dogs secondary to malnourishment and
poor hygiene
– Strep and Staph occasionally cultured from lesions
– Clinical Signs: non-pruritic, non-painful pustules and
papules on abdomen
– Dx: Physical signs
– Tx: Systemic Ab, Ab shampoo q 2-3 days, +/- Topical Ab
cream
– Client Info: Not contagious, usually clears by 6 months
Impetigo
Skin Fold Pyoderma
(aka Intertrigo)
• Occurs in breeds with abundant skin
– Facial folds, vulvar folds, tail folds
– Spaniels, Bulldogs, Pekingese, Pugs, Bostons, obese dogs
• Folds trap moisture, heat and bacteria
• Usually chronic
• Dx: Affected area moist, red, ulcerated
• Tx: Relieve symptoms by cleaning and drying lesion
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Sx reduction of skin fold may be only permanent solution
Weight loss in obese patients
Abs, chlorhexidine-containing pledgets
Antibacterial and/or benzoyl peroxide shampoos
• Client Info
– Require long term medical management
– Keep area dry and clean
– Keep hair/folds away from eyes
Skin Fold Pyoderma – Vaginal Folds
Skin Fold Pyoderma- Facial Folds
Skin Fold Pyoderma – Lip Folds
Acne
• Common in young short-haired dog breeds and cats - can be chronic
• Clinical Signs:
– Chin swollen and painful to touch, dark spots => black heads (comedones)
• Dx: Appearance, r/o bite wounds, abscesses
• Rx:
– clip hair on chin
– clean daily with human acne product (helps with follicular flushing) –
benzoyl peroxide
– systemic antibiotics
– Topical Mupirocin ointment or cream
• Client Info:
– May become chronic
– Daily cleaning of chin
– Use only ceramic or stainless steel bowls – NO PLASTIC
Acne
Deep Pyodermas
• More difficult to treat than Superficial
Pyodermas
• Often chronic
• Patients are often resistant to treatment or
immunosuppressed
• Frequently involves Staph intermedius,
Proteus, Pseudomonas, e. Coli
Deep Pyodermas
• Clinical Signs
– Papules and pustules,
– +/- fever
– Draining fistulas
• Dx: clinical signs
• Tx:
– Thorough cleaning
– Systemic Ab’s (clavamox, baytril, cephalexin)
• Client Info
– Causative organism often drug resistant
– Treatment may be prolonged and expensive in large breed dogs
– Some animals will never fully recovery
Deep Pyoderma
DEEP PYODERMA
Live each moment!
“It is only possible to live happily
ever after on a day to day basis.”
-Margaret Bonnano
Ectoparasites
Ear Mites
• Otodectes cynotis – live on skin surface in external ears
– Feed on epidermal debris
– Clinical Signs: Brown-black, crusty exudate
• Very pruritic, may have excoriations around ears
– Dx: Combine exudate w/mineral oil, observe under
microscope
• Sometimes otoscopic exam will reveal moving debris/mites
– Tx: Clean ears prior to topical medications
• Topical ear medications
– Otomite, Mitaclear, topical Ivermectin, revolution, tresaderm
– Client info:
• Eggs hatch every 10 days; treatment must continue for 30 days
• Highly contagious, treat all animals in house
• No human infection
EAR MITES-TX OPTIONS
Mita clear
applied
topically to
ear canal q
10-14 days
Revolution applied on the back
of the neck or shoulders as directed
q 2 weeks for at least 3 treatments
Tresaderm applied AU BID x 2-3 weeks
Ear Mites
Ear Mites: Otodectes cynotis
Ectoparasites:
Fleas
Flea Life Cycle (Ctenocephalides)
Adult life span: 6-12 months
Female produces avg. of 20-28
eggs/day (up to 50)
Egg production only after blood meal
Incubation period: 2-12 days
Larval stage (needs humidity)
feed on organic material and flea waste
2 molts, then the larva pupates (spins a
cocoon)
Lasts usually 14-21 days
-Pupal stage
-Most resistant
-Lasts days to months dependent on
environmental factors
The Flea
Fleas are very flat from side to
side. They have 3 pairs of legs.
The most caudal pair is designed
for jumping.
Flea Life Cycle
Fleas
• Ctenocephalides felis – The cat flea is the most
commonly isolated flea from dogs and cats
– Flea saliva highly antigenic=> flea bite allergic dermatitis
• Clinical Signs
– Scratching/biting skin
– Alopecia: Dog - base of tail and caudal thighs initially then
generalizes
• Cat- miliary dermatitis
– Flea dirt (flea feces) in hair coat
• Dx: Find fleas or flea dirt
Miliary Dermatitis
Common presentation of flea allergy dermatitis in cats
Flea allergy dermatitis
Common presentation of flea allergy dermatitis in the dog
Fleas
• Treatment
– Topicals: sprays, powders, dips, shampoos
• Shampoos have no residual effect
– Systemic (spot-ons, injectable, tablets)
• Advantage (imidacloprid)- once a month spot-on; causes CNS
paralysis and death of the flea
• Program: (Lufenuron -oral in dogs; injectable in cats);
– absorbed into fatty tissue and slowly distributed into bloodstream;
– Interferes with production of chitin (hard shell)
• Frontline (fipronil) - once a month spot-on; causes CNS paralysis or
death
• Sentinel (Lufenuron + milbemycin)
– Once a month oral tablet (also heartworm preventive); inhibits chitin
formation
• Revolution (Selamectin) – once a month spot-on; causes CNS
paralysis and death; effective for heartworms, sarcoptes, ear mites,
intestinal parasites in dogs and cats
• Comfortis (spinosad) - once a month ORAL tablet; causes CNS
paralysis and death
Fleas
• Client Info
– Treat environment and animal
• Fleas spend most of time off host
• Foggers + vacuum well
– Prefer animals but will feed on humans
– All animals must be treated
– Skin damage/dermatitis can occur
Ticks: Brown Dog and Deer
Brown Dog Ticks:
RMSF/Ehrlichia
(Rhipicephalus sanguineus)
A engorged female
B female
C male
Deer Ticks: Lyme
(Ixodes spp)
D larvae
E Nymphs
F male
G female
H American Dog Tick (wood
tick): RMSF
(Dermacentor variabilis)
Hard ticks
Tick life cycle
Tick life cycle
Female lays 1,000 to 10,000 eggs before dying
Ticks
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Irritation of the bite wound
Vector for diseases
Neurotoxins in saliva of 12 different species
Clinical signs vary with disease
Dx: finding tick; hx of exposure to wooded and grassy
areas
Brown Dog Tick
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The brown dog tick
(Rhipicephalus
sanguineus)
Transmits Ehrlichiosis in
dogs
Brown dog ticks are found
throughout the world.
Dogs are the primary host
for the brown dog tick for
each of its life stages.
Ticks
• Rx: Manually remove ticks
– Grasp head parts close to skin with forceps (NOT HANDS) and pull
backwards; no gasoline, cigarettes, etc.
– Topical treatments (sprays, shampoos, powder, dips)
– Collars
– Topical systemic products
• Client Info
– Routinely check pets for ticks, esp after walks in parks, etc
– Do not use bare hands to remove and kill ticks – blood may
be infectious
– Ticks will feed on humans
Tick paralysis
Dermacentor variabilis
Neurotoxin in saliva of gravid female
Dermacentor andersoni
The Mites
• Large variety of life styles among mites
(free living vs parasitic), skin parasites vs
respiratory parasites, etc.
• Life cycle involves egg, larva (6 legs),
nymph and adult (8 legs).
Burrowing Mites
• Family Sarcoptidae
– Small, round, live in
skin tunnels. Short
legs close to body.
Cause mange.
– Sarcoptes,
Notoedres,
Knemidocoptes
Trixacarus
• Family Demodicidae
– Live in hair follicles.
– Adults cigar shaped.
– Demodex
Mites (Demodectic mange)
Demodex
- Inhabits hair follicles, sebaceous glands or apocrine sweat
glands
- D. canis
- Normal inhabitant in small numbers
- Some cats are asymptomatic carriers
- Spends entire life cycle on host
- Immune system controls infestation
- Genetic predisposition
- Localized or generalized
- Transmission
- Have not seen dog-to-dog or dog-to-human transmission
Demodex
• Demodex cati (right)
• Demodex canis (left)
Demodex
- D. cati
- Similar to D. canis – lives in hair follicles
- D. gati - 2nd most common demodex mite on
cat
- Fat (broad, blunted abdomen)
- Lives more superficial in stratum corneum
- More pruritic
- Associated with immune suppression
- Similar lesions to dogs
Demodex gati
EPIDERMIS
DEMODEX
Demodex
• Clinical Signs
– Localized
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Young dog (3m-1 y);
Alopecia esp on face
Erythema; crusty lesions
Not pruritic unless secondary infections are present
– Generalized
• Often febrile
• Entire body surface involved
– Can result in protein loss through wounds
• Secondary bacterial infection - pustules
• Dx – skin scraping - deep
Demodex: Localized
Demodex: Generalized
AUG 10 2003
Demodex: Generalized
Demodex
• Tx
– Localized – Rotenone (Goodwinol) topical daily or mupiricin (Bactroban)
– Generalized
• Mitaban (amitraz) dips q 7 days x 3-6 treatments or 2 negative skin scrapings
– Side Effects – sedation for 12-24 hrs (up to 72 hrs)
• Ivermectin: 0.3 mg/kg SQ repeat q 14 days OR PO SID x 60-90 days
extralabel use – client sign a release form – Not herding breeds
• Interceptor: 1/mo x 3 mo or more
• Oral antibiotics for secondary bacterial infections
• Client Info
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Many animals outgrow demodex as they age
Not contagious to humans
Tx does not completely remove mites
If breeding dog, then do not treat and do not breed if does not clear on its
own
– Strongly recommend OHE with treatment or will relapse with heat cycles
– Generalized form can be fatal.
Demodex Rx
Approved
Not FDA approved
SQ or PO
Approved
Demodex
• Newer drugs and protocols
– Ivermectin – lower initial dose due to side effects, then gradually
increase dose over several days; 300-500 µg/kg PO SID x 90 days
• SE: ataxia, bradycardia, mydriasis, resp arrest, salivation, stupor and
tremors
– Milbemycin (Interceptor) – 2 mg/kg PO SID x 30-45 days
• Fewer SE
• Expensive for large dogs
• Continue for 4 weeks post 2nd negative skin scraping – may be cost
prohibitive
– moxidectin + Imidacloprid (Advantage Multi)
• Only APPROVED treatments
– Amitraz (Mitaban)
– Moxidectin + imidacloprid in topical formulation (Advantage Multi)
– Milbemycin oxime (Interceptor) orally
Mites (Sarcoptic mange [Scabies])
Sarcoptic Mange
- Species specific
- Adults live 4-5 weeks
- Egg-larva-nymph-adult cycle
- 17-21 days
- Entire life cycle on skin
- Infective in house environment for 24-36 hrs
- Burrows under skin – stratum corneum
(epidermis)
- Hypersensitivity reaction
SARCOPTES
Sarcoptic mange
• Clincal Signs
– Red crusty lesions on ears, elbows and trunk
– Intensely pruritic
– Progressively more severe
• DX – skin scraping; difficult to find mite
• Tx – easily killed
– Amitraz dip q 14 days
– Ivermectin SQ or PO q 14 days (extralabel use)
– Selamectin (revolution) – topically q 2 weeks x 3 treatments
• Client Info – highly contagious to other dogs and
humans
Burrowing Mites
• Sarcoptes scabei
Scabies: Clinical signs
Sarcoptes Rx
Approved
Not FDA approved
SQ or PO
Cheyletiellosis
(Nonburrowing mites)
Cheyletiella spp
Cheyletiellosis
- “walking dandruff”
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Dogs, cats, rabbits, humans
Live in keratin layer of skin
Feed on lymph
Eggs deposited on hair shafts
- Eggs smaller than louse eggs
Life cycle completed in 5-6 weeks
Highly contagious among animals
- Direct contact and fomites
Cheyletiellosis
• Clinical Signs
– Severity of pruritis varies
– Dry scales along back => entire body
– Patchy hair loss from scratching
– Dx: collect scales with clear tape, flea comb, skin
scraping and ID with microscope
– Rx: Weekly baths with flea control products
containing pyrethrins or permethrin and/or lime
sulfur dip
Warbles (Cuterebra)
• Adult fly lays eggs in soil => larvae penetrates
skin of animals=>matures=> leaves animal to
become an adult fly
• Dx: swelling of skin behind ears with opening –
can see larvae
• Tx:
– Surgery: open fistula and remove
larvae
– Flush wound (betadine, Nolvasan)
– Oral antibiotics for skin infection
• Client Info: keep animals in fly-free environment
Warbles (Cuterebra)
Warbles (Cuterebra)
Botfly, family cuterebra
EDUCATION
“Education is a progressive discovery
of our own ignorance.”
-Will Durant
Myiasis (Fly maggots)
Botfly ( Order Diptera)
Myiasis
• Many spp of flies lay eggs on wet, warm, damaged skin =>
larvae are maggots
• Dx: visually seen under matted hair with foul odor
• Rx: Clip hair
– Flush wound, clean daily
– Antibiotics
– Keep indoors to prevent re-infection
• Client info
– Disease of neglect
– More common in heavy coated animals in summer
– Do not use dips to remove maggots
Dog Lice (Linognathus setosus)
Dog Lice
• Host specific; disease of neglect
• Dx: lice cause intense itching
– Blood suckers => anemia if heavy infestation
– Presence of lice or nits or eggs diagnostic
• Rx
– Treat all animals in house with dip, shampoo or dust
• Topical insecticides used for fleas and ticks are adequate
– Wash bedding thoroughly
– Ivermectin orally (extra-label use)
• Client Info
– Humans don’t get lice from pets
DOG LICE
Dermatophytes
Microsporum canis
Dermatophytosis (Ringworm)
Dermatophytosis
• Superficial cutaneous infection
• 3 primary dermatophytes
– Microsporum canis
– Trichophyton mentagrophytes
– Microsporum gypseum
• Cat: 90% M. canis; Dog: all 3
• Transmission
– Direct contact
– Contact with infected hair and scale
– Fomites
• Spores small and easily aerosolized
• Fleas
• Infected hairs – infective for up to 18 months
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Incubation period 1-3 weeks
M. canis – cats
Trichophyton – rodents or nests
M. gypseum – geophilic (soil)
More common in moist, warm environments
Dermatophytosis
• Clinical Signs
– Hair loss, scaling and crusting
– +/- pruritus
– Cats
• Mimics other skin diseases
• Kittens – facial 1st
• Can form ulcerated dermal nodules
– Dog
• Focal or multifocal areas of hair loss
• Papules, scales and crusts
• Central area of hyperpigmentation
Dermatophytosis
• Dx:
– Wood’s Light – UV light
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Quick and easy screen
50% of M. canis fluoresce, rest do not
Differentiate from scale, dust, dirt
Lamp must warm up for 5 minutes prior to exam.
Wood’s lamp
Dermatophytosis
• Dx
– Fungal culture – definitive
• Color change to red in 1-3 weeks
• Confirm with microscopic exam
• Tx
– Usually self curing in healthy animal – may take 2-3
months, esp in kittens
– 3 elements
• Topical – reduces contamination on hair coat
• Systemic- reduces healing time
• Environmental-decreases contamination and spread
Microsporum canis
Trichophyton mentagrophytes
Microsporum gypseum
Dermatophyte Test Media - DTM
Dermatophytosis – Treatment
• Clip haircoat, particularly long hairs
• Topicals
– Spot treatment may predispose to subclinical
infections
– Whole body shampoos, dips, rinses twice weekly
• Lime-sulfur at 8oz/gal (4 oz not effective)
• Miconazole containing shampoos
Dermatophytosis-Treatment
• Systemic tx
– Griseofulvin (don’t use in pregnant animals: teratogenic effects)
• GI absorption variable
• Adverse effects
– Vomiting/diarrhea, anorexia
– Bone marrow suppression
– Neurologic signs
– Ketoconazole (Aplastic anemia in FIV + cats)
• Potential liver toxicity
– Intraconazole
• Less Side effects
– Lufenuron – inhibits chitin formation; chitin in outer wall of fungi
• Being studied
– Tx till resolution of signs and 2 negative cultures
Dermatophytosis – Treatment
• Environment
– Remove or discard all bedding, brushes, fabric
toys, etc
– Cheap vacuum to clean with, then discard
– Clean all surfaces; use bleach
– Vacuum daily
– Disinfect weekly
– Catteries – strict isolation
Dermatophytosis – Zoonosis
• At risk populations: children, immune
suppressed adults, older adults
• Vaccine – reduces severity but not occurrence
of disease
– May not be available now
• Cats can be carriers w/o clinical signs
Ringworm (human)
Atopy (Atopic dermatitis)
Def: Allergy to inhaled environmental
substances and manifested through
irritation of skin and ears, usually
starting at 1-2 yrs of age
Allergens:
Dust mites
Pollens
Feathers
Molds
Animal and human dander
Tobacco smoke
Clinical Signs:
Pruritus
Self-trauma to skin +/- secondary bacterial
infection
Staining of hair from saliva
Licking/chewing feet
Alopecia, scaling, hyperpigmentation
Atopy
• Dx
– Accurate hx critical
• R/o food allergies, flea allergy dermatitis, sarcoptic mange, contact
dermatitis BEFORE diagnosis of atopy can be made
– Intradermal skin testing – most accurate to identify offending allergen
• Tx: No cure
– ID and eliminate cause best treatmetn
– ATOPICA – contains cyclosporin A (immunosuppressor), Antiinflammatory and antipruritic
– Treat any bacterial or fungal infections before using immune
suppressive drugs
– Medication (steroids, Abs) and allergy shots (desensitization)
– Omega 3 fatty acids
– Antihistamines-more effective if given before symptoms occur
Atopy
Alopecia and erythema of
the periocular skin and
alopecia, erythema, and
hyperpigmentation of the
muzzle.
Alopecia and
hyperpigmentation of the
muzzle.
Atopy: Appearance
Skin Testing
Skin testing is performed to identify the allergens involved in allergic disease.
Under profound sedation an area of hair on the chest is shaved and small
injections of substances known to be possible allergens made. After 15-20 minutes
the reactions are recorded
Food Allergies
• 10% of all allergies
• Usually starts between 2-6 yrs
• Processed foods increase likelihood of reaction
– Fillers, artificial colors, preservatives
Food allergies in dogs
Food Allergies
• Dx and Tx
– Elimination diets: new source of protein for 3 mo.
– If improves, reintroduce original protein to see if
symptoms recur – confirmation of dx
– Use new diet.
– May develop allergies to new diet later
Treatment
Food allergies
Treatment
Foods can be obtained based on venision and potato, fish
and potato, egg and rice, duck and pea, and even
kangaroo. Generally recommends duck and potato based
foods for dogs
How do you diagnose food intolerance
(food allergy)?
• The patient is fed a hypoallergenic diet for 6090 days. This allows the body to become
desensitized to the offending allergens. When
the previous diet is fed back to the pet, an
acute hypersensitivity reaction may occur. This
helps to identify that a food was the source of
the allergic signs
Pruritits Algorithm
• Dogs
• Cats
Evaluating Feline Pruritus
• Feline Food Allergy
– Year round pruritus
– Variable response to steroids
– 10-30% with concurrent GI symptoms
• Common offending proteins
-Dairy, fish, beef, pork, chicken, rabbit, horse,
lamb, eggs, clams, "commercial diets"
Managing Feline Pruritus
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Diagnosing food allergy
10 week food trial
Home cooked meat
Potato/rice
Canned food
Innovative Veterinary Diets (IVD)
Green pea & duck/rabbit
Hills ZD???
Allergies
References
• Alleice Summers, Common Diseases of
Companion Animals
• Dr. Ralf S. Mueller, Dermatology for the Small
Animal Practitioner