Final Exam - Skin Flashcards
Scale…
keratinized skin cells
Causes: keratinization disorder and chronic dermatitis
PP: inflamm./repair & disorder of growth
Crusts…
dried exudate, serum, blood and scale adhered to skin surface
Causes: pustular dermatitis, keratinization disorder, secondary to ulcers
PP: degeneration and necrosis and inflamm./repair
Epidermal Collarette..
circular rim of scale occurring secondary to rupture of a vesicle, papule or pustule
When you see Epidermal Collarette, THINK…
ruptured pustules!
- Dermatophytosis - “Ringworm”
- Demodex - Demodicosis
- Superficial Spreading Pyoderma
Ulcer..
loss of epidermis, basement membrane and exposure of dermis
Causes: secondary to - epidermal necrosis, inflammation, infarction, neoplasia
PP: autoimmune/viral, circulatory disorders, growth disorders, degeneration and necrosis, and inflamm./repair
Lichenification…
thickening/hardening of skin
“elephant skin”
Causes: chronic inflammation/irritation
PP: Inflamm./repair
Vesicle/Bulla…
elevation filled with clear fluid; palpable
Vesicle 1cm
Causes: autoimmune dermatoses, viral infs., chemical irritants, burns
Changes that lead to vesicle/bulla formation…
intercellular edema “spongiosis”
intracellular edema “hydropic degeneration”
disruption of intercellular junctions “acantholysis”
Sheep w/ Alopecia, Crusts, ulcers, Erythema and Edema….indicating disruption of the epidermis…what is the PP?
Degeneration/Necrosis
Inflamm/Repair
DDx: Photosensitization
Dermatophilus
Viral Infs. - bluetongue, pox (orf), vesicular disease (FMD, VS)
Pustule…
palpable elevation filled with pus
Causes: leukocyte infiltration
PP: inflamm/repair
Pathogensis of Photosensitization…
UV light absorbed by photodynamic chemicals in skin –> free radical damage –> epidermal necrosis of lightly pigmented or sparsely haired skin
Plaque…
Elevated, firm flat lesion >1 cm in diameter (coalesced papules)
Papules/Nodules…
Elevated, firm, circumscribed mass within the dermis
papule 1 cm
Causes: infiltrate of inflammatory cells, neoplastic cells, epidermal hyperplasia, or mineral deposits
PP: inflamm, growth disorder or deposits/pigments
Most Degeneration/Necrosis skin lesions have these features…
epidermal necrosis/ulceration
bacterial infection
leukocyte infiltration
Type I/Primary photosensitization (Exogenous)
ingestion of preformed photodynamic substances…
Plants: St. John’s Wort, lucerne, perennial ryegrass
Type II Photosensitization (Intrinsic)
porphyria; inherited deficiency in proporphyrinogen III cosynthase –> defect in heme synthesis –> build up or porphyrins
TypeIII/Secondary Photosensitization (Hepatogenous)
poor hepatic clearance of phylloerythrin –> biliary obstruction from toxins
Ex: Lantana, steroidal saponins, sporodesmin, pyrrolizidine alkaloids: aflatoxin and phomopsin
Solar Injury
UV mediated endothelial damage and cytokine production
Acute UV light exposure –> “sunburn” –> erythema–> blisters/vesicles–> sloughing of necrotic skin
Solar/actinic keratosis –> yrs of UV light exposure –> epidermal hyperplasia and dermal fibrosis/elastosis
Direct DNA damage and subsequent mutations –> increase risk of neoplasia
1st Degree Burns
superficial; epidermis; red/dark necrotic epidermis; complete healing
2nd Degree Burns
epidermis and dermis involved; blisters/vesicles form; adnexa preserved so some regeneration w/ scarring
3rd Degree Burns
epidermis, dermis and submits involved; sloughing; scarring; potentially life-threatening
Cardinal signs of Inflammation…
erythema, edema, pain/itch, heat, exudate
MDx for Inflammatory Skin Lesions…
“Blank Blank Dermatitis”
Gross features of Early Dermatitis…
erythema, edema, +/- pustules, crusts, vesicles
Gross features of Late Dermatitis…
alopecia, ulcers, scales, lichenification, pigmentary changes, fibrous/scarring
Impetigo…
superficial pustular dermatitis; nonfollicular pustules that develop into crusts; prepubescent puppies - healthy otherwise; in adults, look for an underlying disease
Intertrigo…
Skin Fold Pyoderma; Closely apposed skin –> Frictional trauma + Moisture –> Opportunistic bacterial infection
Erythema; MDx: neutrophilic dermatitis
Think English Bulldogs!
Pyotraumatic Dermatitis
“Hot Spots”; self trauma –> bacterial infection –> alopecic
underlying pruritis usually from FAD; moist, alopecic, slightly raised red, well-circumscribed lesions –> ulcerating/crusting
Pyoderma…
pus/inflammation of the skin; usually accompanied by bacterial inf.
Alopecia..
absence of hair from a normally haired site
Superficial Pyoderma…
includes epidermis and hair follicles Ex: Greasy Pig Disease bacterial folliculitis Impetigo Dermatophilosis
Deep Pyoderma…
deep dermis
Ex: bacterial furunculosis
abscess
“Dog with Chin acne”
Greasy Pig Disease - Staphylococcus hyicus…
Exudative epidermatitis; erythema –> pustules –> crusts
Predisposing Factors: Skanky environment, lacerations, poor nutrition/husbandry
Dermatophilus congolensis causes “Rain Rot” in Horses or “Lumpy Wool” in Sheep. What are the Predisposing Factors? Path./Lesions?
Dermatophilosis along the back (where animals get rained on); colonizes skin surfaces –> zoospores proliferate and penetrate epidermis –> stimulate neutrophil exocytosis –> pustules –> exudate –> matting of hair/wool –> alopecia
Predisposing Factors: wet/humid weather
Demodicosis…
Causative agent: Demodex spp.
folliculitis, erythematous macules, ring-shaped alopecia, scaling
Indistinguishable from Canine Superficial Spreading Pyoderma
Localized - face and forelimbs
Generalized - linked to immunosuppression, neoplasia, and endocrinopathy
Dermatophytosis…
Causative agents: Keratinophillic fungi Epidermophyton, Microsporum, and Trichophyton spp.) - colonize keratin
Folliculitis, erythematous macules, ring-shaped alopecia, scaling
Indistinguishable from Canine Superficial Spreading Pyoderma
Directly contagious - direct contact with infected scales; No Predisposing Factors needed; common in: immunocompromised or young animals in hot/humid environments
Acantholysis…
loss of cohesion between keratinocytes; viral vesicle formation
Seen w/ pemphigus diseases and superficial bacterial infections
Pemphigus foliaceus…
Auto-immune diseases involving Type II Hypersensitivity against cell adhesion proteins (desmosomes)
Most common, milder form in Horse, Dog, Cat, and Goat
CS: vesicles, pustules, crusts and ulcers
- often involves: face, ears, footpads, clawbeds
- aberrant/spontaneous, drug-induced or associated with allergic skin disease
-subcorneal vesicle formation; common in dogs with acantholytic keratinocytes w/ eosinophils and few neutrophils
Sheep with early papular to vesicular scabs/crusts and later crusty exudative lesions…
ORF - contagious exanthema
MDx: papular/vesicular dermatitis/cheilitis
ZOONOTIC
Pox Viruses…
Proliferative; epidermal hyperplasia;
Cause: cutaneous lesions; proliferative dermatitis
macule -> papule -> vesicle/bulla -> umbilicated pustule -> crust -> scar
In backyard livestock, you see anorexia, ptyalism (hyper salivation), lameness, ulcerations and look around and find vesicles. What are the PP? Lesions? MDx? DDx?
PP: Inflammatory or Degeneration and Necrosis
Lesions: Ulcers…but you look around and also see Vesicles/Bulla
MDx: Vesicular Dermatitis
DDx: Viral Vesicular Diseases, Early Herpesvirus, Early Poxvirus
What are the Vesicular Diseases and who do they infect?
Foot and Mouth (FM) - everyone but horses
Vesicular stomatitis (VS) - everyone
Vesicular Exanthema of Swine (VES) - pig, fish, marine mammals
Swine Vesicular Disease (SVD) - swine only
The only way to distinguish between the Vesicular Diseases is through…
lab testing
Herpesvirus can cause…
Cutaneous vesicles…Vesicular Dermatitis
Vesiculo-ulcerative dermatitis in cattle due to BHV-2 is called…
Pseudo-lumpy Skin Disease
T/F - BHV-2 can also cause vesiculo-ulcerative mammilitis in cattle.
True
Panniculitis…
inflammation of adipose
