SA Med 1

• Pluck hair with hemostat
• Place in mineral oil on microscope slide
• Cover with cover slip
• Examine with dry objectives

• Do not wash or prepare site!!!
• OK to gently clip hairs
• Use SQ lidocaine for anesthesia (fractious animals use sedation)
• Place biopsy in 10% neutral buffered formalin
• Specimen size to solution volume should be at least 1:10
• Nasal planum, footpads, oral ulcers need general anesthesia

magnification + lighting, e.g. otoscope with no cone

• Wood’s lamp should be turned on for 5- 10 minutes before use
• Fluorescence is apple-green in color, and follows hair shafts

• Press on lesion
• Place on slide sticky side down, (dry for cytology, mineral oil for parasites)
• Look for parasites (4x & 10x)
• OR
• Stain for bacteria & yeast (100x)

• Collected with needle +/- syringe
• Material placed on dry slideHeat fix
• Rapid stain (Diff-Qwik ®)
• Scan for areas of interest with 4x objective, then use 100x with immersion oil

• Collect material w/ cotton swab
• Roll material on dry microscope slide
• Heat fix
• Rapid stain (Diff-Qwik ®)
• Scan for areas of interest with 4x objective, then use 100x with immersion oil

Pressure applied on the skin through clear plastic or glass to determine if erythema is due to vascular dilatation or bleeding into the skin

• Clip heavily haired areas
• Place small amount of oil on spatula
• Scrape blade across skin perpendicular to the surface
• Place material in mineral oil on slide
• Cover with cover slip
• Examine with 4x or 10x objective

• Spatula or #10 blade
• Clip heavily haired areas
• Scrape dry blade across skin perpendicular to the surface
• Always superficial
• Smear material on dry slide
• Heat fix
• Rapid stain (Diff-Qwik ®)
• Scan for areas of interest with 4x objective, then use 100x with immersion oil

It's either contagious, nutritional or toxic etiology

pyoderma, demodex, dermatophytosis

• wedge (better for deep, fragile lesions; takes more tissue, more time, GA usually)
• punch (easier, speedier, fewer sutures; can get smaller sample, more traumatic, hard to orient)

topical medications, dander

• A large vesicle
• Bulla can form in the epidermis, between the epidermis and dermis, (dermal-epidermal junction), or within the dermis

• Narrow rim of loosened stratum corneum that overhangs peripheral edge of acircumscribed skin lesion
• Evolve from pustules
• Post inflammatory hyperpigmentation or non pigmented halo along w/ footprints of previous pigmentation

• Accumulated fragments of cornified epidermal cells (scale) plus dried residue of serum, blood, or pus
• Crusts imply inflammation

• A circumscribed change in skin color without elevation or depression of the surface.
• Epidermis only

• Large papule or solid, deep-seated mass in either dermal or subcutaneous tissue
• Dermal nodule: skin and nodule move over underlying tissue
• Subcutaneous nodule: skin moves over nodule and underling tissue

• A circumscribed solid elevation of the skin, implies involvement of both the epidermis and dermis
• The most common skin lesion

A large macule

• A large, usually flat-topped circumscribed elevation of the skin
• Plaques often evolve from confluent papules

• A circumscribed elevation of the epidermis containing purulent material (pus)
• A vesicle containing pus

• Accumulated fragments of dead, cornified epidermal cells (stratum corneum)
• Scale results from altered keratinization or cornification

Large nodule or neoplastic mass

• A circumscribed elevation of the epidermis containing serous fluid
• Vesicles are fragile & readily rupture

• A well-circumscribed flat-topped firm elevation of the skin with a well-demarcated, palpable margin
• Produced by dermal edema - wheals should pit

• Superficial denudation of the skin confined to the epidermis
• Erosions do not damage or breach the dermal-epidermal junction (BMZ)
• Erosions ooze serum, but do not bleed

• A defect of the skin extending through the dermal-epidermal junction (BMZ ) into the dermis or even deeper
• Ulcers bleed
• Includes pemphigus foliaceus

• A lesion produced by self-trauma (underlying pruritus)
• Excoriations can be either erosions or ulcers

• A thickening of the skin (usually with hyperpigmentation) with increased prominence of the normal surface epidermal architecture
• Indicates chronicity of skin disease ± self-trauma

sensation that elicits a desire to scratch

culture

• Spatula or #10 blade
• Mineral oil on microscope slide
• Glass cover slip

• surface: scabies (notoedres), cheyletiella, chorioptes
• follicular: demodex

• No response to staph abx
• Maybe if have been on abx in last 6-12 months

pruritis (see broken hair ends), demodicosis / liec / cheyletiella (eggs or parasites on hair), color dilution (melanin clumping on outisde of shaft), dermatophytes, follicular casting

~60% of Microsporum canis fluoresce = diagnosis of dermatophytosis

neoplasia, bacterial and systemic fungal infections

bacterial, systemic fungal, otitis externa, anal saculitis, pemphigus foliaceus

Yeast (malassezia), bacterial (staph, secondary)

tryptophan metabolite that is produced only ON the animal

• Dermatomes supplied with large sensory nerves that terminate in free nerve endings
• & more specialized receptors 

Touch, temperature, pain, pruritus

• Specialized corpuscular receptors - Pacinian and Meissner’s corpuscles Ruffini’s end organs, Merkel’s discs
• These are mechanoreceptors (pressure,
• vibration) – do they transmit pruritus?

• Sensation of itch carried centrally from free nerve endings by:
• - Non-myelinated, slow conducting C fibers most important (pruritus, pain, heat)
• - Myelinated, rapid conducting A delta fibers (noxious stimuli, cold)

lateral spinothalamic tract

• Specificity theory: different subsets of nociceptors transmit pain or pruritus
• Pattern theory: spatio-temporal pattern of
• neural activity permits distinction
• Central processing theory: central processing differences permit distinction between the two sensations

Histamine, PgE1, leukotrienes (LTB4), opioid peptides, substance P

• What happens IN the animal
• A certain pruritic load may be tolerated by an individual without provoking clinical signs, but an increase in that load may push that individual over the threshold initiating clinical signs of pruritus

• What happens TO the animal
• Additive pruritic stimuli from different chemical mediators or coexistent skin diseases may raise an animal above its individual pruritic threshold 

• Anagen stage - Mitotically active hair growth phase
• Catagen stage - Involutional, no growth
• Telogen stage - Long transitional ‘resting’ phase, no active metabolism
• Exogen stage - brief phase, telogen hair is shed 'pushed out' by new anagen hair

• Endocrine disease - Hormonal status
• Vascular sustenance - Ischemia of hair follicle
• Inflammation - Near hair bulb
• Metabolic abnormalities
• Dysplasia - Genetically pre-programmed 

• Traumatic - Common, secondary to pruritus
• Non-traumatic - Less common
• Congenital - Rare, inherited, permanent
• Acquired - Common, many causes
• Cicatricial - Follicular destruction & scarring (much more common in humans)
• Non-cicatricial - Hair regrowth possible if causative factors can be identified & corrected

• Predictable, dose dependent
• Anti-metabolites, other immunomodulators
• Alopecia, purpura, poor wound healing, infection

• Not predictable, relatively dose independent
• Abnormal production of IgE, IgA, IgG, IgM
• Immediate, cytotoxic, immune complex or delayed hypersensitivity

can mimic any skin disease

medial pinna, ventrum, oral cavity, generalized

Was on a drug previously, stopped, was put back on it in last 2 weeks, developed cutaneous symptoms

• Toxic epidermal necrolysis
• Erythema multiforme (minor & major)
• Vasculitis
• Pemphigus foliaceus
• Urticaria
• Maculopapular eruptions
• Injection site drug reactions
• Erythroderma
• Exfoliative dermatitis
• Purpura
• Fixed drug eruptions
• Vesiculobullous reactions
• Lichenoid drug eruptions
• Sterile pustular erythroderma (Superficial suppurative necrolytic dermatitis)

Neoplasia, infection, idiopathic, cutaneous adverse drug reaction

• Erythematous macules and papules, target lesions, erosions, ulcers, collarettes
• Sites - Truncal (esp. ventrum), mucocutaneous junctions, face, ears 

• Macular erythema -> confluent erythema, ulceration, pain. The whole skin will slough -> sepsis -> DIC -> death
• Sites - Face, trunk, mucocutaneous junctions, pawpads

• abx: TMS, penicillins
• NSAIDs: ace, bute (horses only)

• When treating otitis externa, applying topical flea control
• Will see lesions at site of application, except Promeris

• Withdraw suspected drug (if not known, withdraw all drugs)
• Avoid the suspect drug & all related drugs in the future
• Supportive care
• Depending on the cutaneous reaction immunosuppressive therapy may be indicated 

• Most self-limiting after drug withdrawal (within 2-14 days)
• E.M. - Potentially life-threatening
• T.E.N. - Always life-threatening

• keratin (dead), therefore skin, hair and claws
• can penetrate deeper in immune compromised animals or when trauma present

Microsporidium, Trichophyton, Epidermophyton

cats

rodents

soil

• T. equinum
• T. mentagrophytes
• T. verrucosum
• M. equinum

humans, so reverse zoonosis

young age, poor nutrition, stress, debilitating disease, immune compromised

alopecia, scaling, crust, papule, erythema, pruritus, weak keratin

M. canis

• face, ears, legs
• asymmetrical!

face, tail, feet

Tumor-like form of dermatophytosis, is exudative and can look for fungal hyphae on smear

likely T. mentagrophytes from chasing burrowing rodents

alopecia, crusts, papules, pustules

• initially urticarial
• alopecia and crusts in area of tack
• can affect only the coronary band

hair pluck (KOH or chlorphenolac clearing agents), Wood's Lamp fluorescence, biopsy with special stains, culture (definitive)

DTM (should turn red within 48 hours of growth) +/- Sabouraud's (allows for colony ID)

colony is white of pale tan, fluffy, turns agar red in first 48 hours of growth, growth occurs within 3 weeks of inoculation

terminal knob on M. canis

• self cure in 3 months (contagious and shedding during)
• systemic, topical + environmental txt needed
• systemic: imidazole, terbinafine, griseofulvin
• topical: imidazole (esp enilconazole), chlorhexidine, lime-sulfur
• environment: 100% bleach or throw away
• tx until 3 negative cultures 1-2 weeks apart

ketoconazole, fluconazole

itraconazole, fluconazole

• GI upset, hepatopathy, drug interactions
• Renal clearance in fluconazole

• give with high fat meal for absorption
• animals > 12 weeks old and not pregnant
• AE: V. leukopenia (esp FIV+), teratogen

• inhibits chitin production
• give with meal
• likely ineffective, but very safe

• NaI, griseofulvin (not if pregnant)
• fluconazole

Smells terrible, stains sterling silver, stains white hair to yellow, very effective, safe for any age

• smaller lesions
• T. verrucosum successful in cattle

seborrhea, allergy, infection

shampoo, pledgets, soaks, dips, powders, lotions, creams, ointments, gels, sprays

normalizes epidermal cell turnover

decreases keratinocyte adhesion

• antibacterial
• antisebhorreic
• antifungal
• antipruritic
• antiparasitic
• moisturizing
• sunscreen
• deterrent

Staph pseudintermedius (otitis externa and superficial pyoderma), rarely P. aeruginosa

• antibacterial
• keratolytic
• degreasing
• *works well with sulfur*
• warning: bleaches fabrics and hair, very drying

• antibacterial (lowers skin pH)
• "elegant shampoo"

• antibacterial
• antifungal (>3%)
• animal can be dirty (ok to have organic debris)

• antibacterial
• antifungal (yeast)
• antisebhorreic (keratoplastic and keratolytic)
• antipruritic

• antibacterial
• topical only, nephrotoxic on MM

• antibacterial
• use with sulfur / salicylic acid

• antibacterial
• antifungal
• promotes re-epithelialization, good for burns

antibacterial, but very irritating

• antibacterial
• antifungal
• humectant

Ketoconazole, Miconazole, Clotrimazole, Enilconazole, Chlorhexidine, Thiabendazole, Nystatin, Lime sulfur 

• antifungal
• antiparasitic (sarcoptes, cheyletiella, notoedres, lice, chiggers)

• Disturbance of epidermal cell turnover time that results in excessive scaling and crusting
• Can be oily, greasy or dry forms

• antiseborrheic
• local anesthetic
• *toxic in cats*
• smells bad

• Spot-on flea txt
• monoamine oxidase inhibitor
• antiparasitic (demodex, sarcoptes, cheyletiella, otodectes, notoedres)
• *can be toxic*

colloidal oatmeal, corticosteroids, topical lidocaine or pramoxine, antihistamines, tar (not in cats!), sulfur

• anti-inflammatory
• immunosuppressive
• antimitotic

• inhibits CMI
• decreases cytokines
• decreases lymphocytes

• pu, pd
• polyphagia
• protein catabolism
• fat redeposition
• GI ulcers
• immunesuppression
• silent uti or pyoderma
• adrenal gland atrophy
• mood changes
• hepatopathy
• develop DM
• laminitis in horses
• derm: skin atrophy, comedones, hyperpigmentation, alopecia (increased telogen follicles), bruising, poor wound healing, infections, calcinosis cutis

• increased GFR + inhibits ADH -> loss of Na and water = pu
• pu -> pd

• PgE2 is protective of gastric mucosa
• *never use with NSAIDs for this reason*

• dystrophic calcification of skin = ossification of dermal collagen
• see on ventrum and dorsal neck

hydrocortisone, cortisone

prednisone, prednisolone, methylprednisolone

triamcinolone, dexamethasone, bethamethasone

2x dog dose