derm disorders

what is the definition of alopecia?

absence of hair

what is the definition of hyperpigmentation?

excessive coloration of the skin caused by increased deposition of melanin

what is the definition of erythema?

redness of the skin related to vasodilation or free hemorrhage

what is the definition of pruritus?

itching

what is the definition of papule?

small solid elevation of the skin, <1 cm in diameter

if a papule is larger than 1cm and flat topped, what would it be called?

plaque

what is the definition of pustule?

small (<1cm) circumscribed elevation of the skin filled with pus

if a pustule is larger than 1cm, what is it called?

abscess

what is the definition of epidermal collarette?

pustule ruptures and leaves a rim of dead keratin

what is a nodule?

small, circumscribed solid elevation extending into deeper layers of the skin

what is a nodule called if it is/becomes neoplastic?

tumor

what is seborrhea/seborrheic?

conditions characterized by increased epidermal turnover and changes in the quantity or quality of sebum - may be greasy or dry

what is lichenification?

thickening of the skin characterized by exaggeration of superficial markings

what is hyperkeratinosis?

increase in thickness of the horny layer of the skin

what is the definition of colonization?

increased numbers of bacteria or yeast in the surface if the skin

what is the definition of crust?

dries exudate on the skin consisting of serum, pus, blood, scales, medications, hair

what is the definition of dermatophyte?

fungus that invadethe length of times keratinized tissues like hair, nails, hooves, etc.

what is the definition of epidermal turnover time?

the length of time for epidermal cells to move from the basal cell layer to the stratum corneum and slough off

what’s the normal epidermal turnover time?

21 days

what is the definition of ulcer?

break in the continuity of the epidermis with exposure of underlying dermis

what do you call an ulcer that hasn’t gone through the epidermis?

erosion

what is the definition of a scar?

area of fibrous tissue that has replaced damaged dermis or subcutaneous tissue

what is the definition of scale?

accumulation of loose fragments of the horny layer of the skin (dandruff)

what is the definition of keratolytic?

agents that helps remove excessive stratum corneum

what is the definition of keratoplastic?

agent that helps normalize epidermal turnover

what is the definition of excoriation?

abrasion of a portion of the skin caused by scratching

what is pyoderma and how can they be classified?

• bacterial infection of the skin

• classified as primary or secondary

which organism usually causes pyoderma?

staphylococcus pseudintermedius

where does the pyoderma infection come from?

• cutaneous insults: dirt, trauma, excess moisture, urine scald, matting, seborrhea

• dermatologic diseases: parasites, allergic dermatitis, endocrine disorders

• immune incompetence

• hypersensitivities

how can you best categorize pyoderma?

according to depth of infection

what is a surface pyoderma infection?

infection that doesn’t penetrate the stratum corneum

what is a superficial pyoderma infection?

infection of the skin involving hair follicles and the adjacent epidermis

what is a folliculitis pyoderma infection?

infection of hair follicles caused by yeast or bacteria colonizing the follicle

what is a deep pyoderma infection?

bacterial infection that breaks through hair follicles to produce furunculosis and cellulitis

what is acute moist dermatitis (hot spots)?

rapid onset of painful and erythematous lesions that can be swollen, alopecic, and exudative

what are skin fold pyodermas?

produced by friction and minor trauma as the moisture and glandular secretions provide a prime environment

what is a superficial pyoderma?

infection of the skin involving hair follicles and the adjacent epidermis

what is superficial pustular dermatitis (impetigo or puppy pyoderma)?

small, nonfollicular pustules, nonfollicular papules, and crusts, limited to inguinal and axillary skin that is nonpainful and not pruritic

what is dermatophilosis (lumpy wool)?

bacteria on skin and fleece becomes an active infection when the animal is exposed to execisse moisture

what is methicillin resistant staphylococcus (MRS)?

gram positive bacteria that have developed resistance to the antibiotic methicillin and other beta-lactam antibiotics including penicillins, cephalosporins, and carbapenems

what are 2 topical treatments that can be sued with resistant bacteria?

• diluted bleach

• hand sanitizer

what are the type of allergies that can lead to pyoderma?

• -atopic dermatitis (environmental)

• food

• contact allergy dermatitis

• flea bite allergy

what are some indicators of pruritis?

• chewing on skin

• scratching at skin

• licking areas of skin

• rubbing against furniture, walls, the ground

• shaking head

what is atopic dermititis?

genetically predisposed inflammatory and pruritic allergic skin disease with characteristic clinical features associated with IgE antibodies most commonly directed against environmental allergens involving the face, ears, feet, under the arms, and back legs

what is the gold standard for atopic dermatitis?

immunotherapy

what are some clinical signs of feline atopic skin syndrome (FASS)?

• pruritus

• respiratory signs such as sneezing and conjunctivitis

how may feline atopic skin syndrome (FASS) manifest?

• symmetrical alopecia

• eosinophilic ulcer

• miliary dermatitis

• eosinophilic plaque

what is immunotherapy?

process of gradually increasing the amount of the substance to which the individual is allergic, given by injection or sublingually

what are food allergies?

allergic reaction to an ingredient in a dog’s diet

what are most dogs sensitive to in their diet?

• proteins: beef, chicken

• dairy

• wheat

• eggs

• corn

• soy

what are the types of food allergies and how long do they take to manifest?

• type I - IgE mediated, may take minutes to hours

• type III or IV - cell mediated, may take hours or days

what are clinical signs to food allergies?

• atopic dermatitis

• year round intching

• GI signs

what common antihistamines are used with atopic animals?

• dogs: doxepin, diphenhydramine, clemastine, hydroxyzine

• cats: chlorpheniramine

what is the major side effect of using antihistamine drugs with animals?

drowsiness

what does cyclosporin (atopica ®) do and what are some side effects?

• blocks the release of inflammatory molecules

• GI signs, gingival hyperplasia

what does oclacitinib (apoquel ®) do and what are some side effects?

• janus kinase inhibitor - blocks a protein that is integral to the signaling pathway resulting in pruritus and inflammation

• GI signs + not recommended for cancer patients

what does cytopoint do?

caninized monoclonal antibody that targets the cytokine interleukin (IL)-31, blocking the itch signal to the brain

what is the difference between allergic contact dermatitis and irritant dermatitis?

• allergic contact dermatitis

  • type IV hypersensitivity

  • usually requires long term exposure

  • plant pollens and resins like ragweed + poison ivy

  • wool, carpet dyes, fresheners, nylon, wood finishes/polishes, rubber

• irritant dermatitis

  • more common

  • substance that physically damages the skin

what are clinical signs of contact dermatitis?

• affects face, feet, ventrum

• variable pruritus

• primary lesions: papules, plaques, macules; rarely vesicles/bullae

• secondary lesions: ulceration, crusting, pigmentary changes, hyperkeratosis, lichenification

• ± pyoderma, yeast, dermatitis

what is dermatophytosis?

infections of the hair, shaft and follicle - contagious and zoonotic, spread by direct contact and fomites

what are the main 3 species of fungi that cause the majority of infections in the dog and cat?

1. microsporum canis

2. trichophyton mentagrophytes

3. microsporum gypseum

which fungi causes dermatophytosis in 98% of cats?

microsporum canis

what are clinical signs of dermatophytosis?

• minimal to intense pruritus

• areas of circular, irregular, or diffuse alopecia with variable scaling

• remaining hairs may appear stubbed or broken off

• erythema, papules, crusts, seborrhea

what are some common derm parasites?

• demodicosis/demodex

• sarcoptes scabei

• feline scabies

• fleas

• cheyletiella (walking dandruff)

T/F - demodex mites can be transferred from dam to puppies

true

what are causes of demodicosis/demodex?

• in young dogs:

  • genetic make-up

  • stress

  • endoparasites

  • malnutrition

  • immunosuppressive drug therapy

  • debilitation

• in adult dogs:

  • neoplastic

  • immunosuppressive drug therapy

  • hormonal diseases

what are clinical signs of localized demodicosis/demodex?

• mild disease

• 1-5 areas of alopecia

• variable erythema, hyperpigmentation, and scaling

what are clinical signs of generalized demodicosis/demodex?

• patchy, regional, multifocal, or diffuse alopecia

• variable erythema, silvery-grayish scaling, papules and/or pruritus

• secondary pyoderma may develop

• peripheral lymphadenomegaly is common

what are the 2 sub-classifications for generalized demodicosis/demodex?

• juvenile onset = 3-18 months

• adult onset = over 18 months

what is sarcoptes scabei?

superficial burrowing skin mite that secretes allergenic substances that elicit an
intensely pruritic hypersensitivity reaction

what clinical signs do you see with sarcoptes scabei?

• intense pruritus

• lesions: papules, alopecia, erythema, crusts, + excoriations

• peripheral lymphadenomegaly

• weight loss

• debility

is sarcoptes scabei zoonotic?

yes 😨

what is notoedres cati (feline scabies)?

superficial sarcoptic mite that causes intense pruritus

what are clinical signs for notoedres cati?

• intense pruritus

• dry, crusted regions

• peripheral lymphadenomegaly

• if left untreated

  • anorexia

  • emaciation

  • death

is notoedres cati zoonotic?

yes 😱

what are fleas?

small, wingless, blood-sucking insects

what is the most common species of flea?

ctenocephalides felis (cat flea)

what is cheyletiella (walking dandruff)?

mite that lives on hair and fur, visit skin only to feed

T/F - only the adult stage of cheyletiella is parasitic

false - all stages of life are parasitic

is cheyletiella zoonotic?

yes 😢

what are clinical signs of cheyletiella?

• excessive scaling over the dorsal midline

• minimal pruritus

• papular, crusting eruptions

what are common derm autoimmune doseases?

• pemphigus foliaceus

• pemphigus erythematosus

• discoid lupus erythematosis

• lupoid onychodystrophy

what’s the most common autoimmune disease in dogs and cats?

pemphigus foliaceus

what is pemphigus foliaceus?

production of autoantibodies that target proteins binding the cells of the stratum
basale of the epidermis

what are clinical signs of pemphigus foliaceus?

• primary lesions are superficial pustules that rupture easy

• secondary lesions

  • superficial erosions

  • crusts

  • scales

  • epidermal collarettes

  • alopecia

  • nasal depigmentation

  • foot pad hyperkeratosis

  • oral lesions are rare

what are the cytologic findings of pemphigus foliaceus?

• hallmark acantholytic cells

• nondegenerate neutrophils and eosinophil

how do we know its pemphigus foliaceus and not pyoderma or dermatophytosis?

you confirm with a biopsy

what is pemphigus erythematosus?

benign form of pemphigus foliaceus or crossover between pemphigus and lupus

which species is pemphigus erythematosus seen in?

mainly dogs like:

• german shepherds

• collies

• shetland sheepdogs

what are clinical signs of pemphigus erythematosus?

• superficial erosions

• scales

• and/or crusts

• +/- pustules, nasal depigmentation and
  erythema, occasionally hyperkeratotic footpads

what is discoid lupus erythematosis?

benign variation of lupus erythematosus

what are clinical signs of discoid lupus erythematosis?

• nasal depigmentation

• erythema

• scaling

• erosions

• ulcerations

• and/or crusting

what is lupoid onychodystrophy?

lupus-like disease causing loss of the nails

what are clinical signs of lupoid onychodystrophy?

painful, misshapen, soft/brittle, discolored, and friable nails

what is a common pain control procedure for lupoid onychodystrophy?

declawing for severely painful cases