Dermatitis 2 Flashcards
What is puppy strangles? What is the gross appearance?
Juvenile sterile granulomatous dermatitis
Pustules, nodules, swelling of face, ears, mucocutaneous junctions
You have a puppy that presents with fever and joint pain. Grossly you see pustules, nodules, swelling of face and ears, and mucocutaneous junction.
You take a biopsy that shows..
granulomaouts dermatitis and panniculitis
What is it?
Puppy strangles
Juvenile sterile granulomatous dermatitis
What are infectious causes of granulomas?
Fungal - pythium and langenidium spp
Bacterial - Nocardia, Actinomyces, mycobacterium
On a dog you see…
nodules, ulceration, draining sinuses with involvement of underlying bone. You also see what appear to be sulfur granules.
What is your DDX?
Actinomyces mycetoma (filamentous bacteria)
Nocardia-> should be ruled out because of involvement of underlying bone
Pyogranulomatous dermatitis
What causes feline leprosy?
Mycobacterium lepraemurium -> obligate intracellular , gram positive bacteria
–> granulomatous dermatitis
What cats are predisposed to feline leprosy?
Cat in cold, wet areas
FIV/debilitation
T/F: feline leprosy can be diagnosed by culturing the bacteria
F
DOES NOT grow in culture
Must use PCR
What is the cause of opportunist mycobacteriosoiss?
Facultative saprophytes
Infection tends to occur in wound contamination or traumatic implantation
In a Boxer you see..
Nodules involving the dorsal pinna.
What is the most likely cause?
Canine leproid granuloma
Saprophytic mycobacterium
How can you diagnose canine leproid grauloma ?
Difficult to culture
PCR
Can usually be found on histo-> acid fast
What is a lick granuloma?
Common in dog
- not really a granuloma!
Epidermal hyperplasia, granulation tissue, fibrosis
Caused by persistent licking/chewing
What are the gross lesions of a eosinophilic dermatitis?
Erythema
Alopecia
Scaling
Your histology report comes back with…
Eosinophilic dermatitis with epidermal hyperplasia.
What do you suspect the cause is??
Allergic skin disease
What are the 4 types of allergic skin disease
Atopic
Food allergy
Contact hypersensitivity
Insect bite hypersensitivity
Grossly you have a dog with..
erythema, alopecia, and excoriation
Papules, pustules, and crusts,
Lichenifiication, hyperpigmentation
Histology shows..
lymphocytic and eosinophilic dermatitis
Allergic skin disease
In allergic skin disease, erythema, alopecia, and excoriation is due to __________________, papules, pustules, and crusts are due to ________________, and lichenifiication and hyperpigmentation is due to _____________.
Self- trauma
Secondary pyoderma
Chonicity
What is the pathogenesis of atopy?
Type 1 hypersensitivity to environmental allergens
What is the distribution of atopy??
Ventrum
Face
Distal extremities
What is the pathogenesis of contact dermatitis ?
Type 4 hypersensitivity -> exposure via direct contact
What type of molecules cause contact dermatitis? And how do they cause the inflammatory reaction
Low molecular weight haptens present in chemicals require binding to cell-associated proteins prior to being recognized by CD8+ Tcells
What is the distribution of contact dermatitis?
Depends on site of contact, often poorly haired areas
What is the pathogenesis of insect bite hypersensitivity ?
Type 1 and 4 hypersensitivity
What is the distribution of insect bite hypersensitivites ?
Depends on area of bite, but can become generalized
What military dermatitis?
Pattern of lesions (NOT a disease)
Small erytematous papules - commonly seen in cats with allergic skin disease
What is eosinophilic granuloma complex?
Pattern of lesions (Not a disease )
Indolent ulcer
Eosinophilic plaque
Eosinophilic granuloma
What are causes of eosinophilic granulomas?
Parasite reaction
Insect bite hypersensitivity
Forgiven body reaction
What is an indolent ulcer?
Ulcer on upper lip
What is an eosinophilic plaque?
Discrete red to ulcerated plaque on abdomen or medial thigh
What is an eosinophilic granuloma?
Nodules on thigh, face, or mouth
Horse
Multiple coalescing nodular granulomas and ulcerated areas in medial canthus of the eye
What is the MDx and the most likely cause?
Eosinophilic and granulomatous dermatitis
Habronemiasis (summer sores)
-> larval migration of Habronema or Draschia sp. -» deposited by house or stable flies
On a doggo you see…
Depigmentation, erythema, scaling, erosion, ulceration, and crusting at the junction of the nose-> muzzle
What is your DDX?
Uveodermatologic syndrome - auto-immune disease against dermal and uveal melanocytes
Dermtomyositis
What is the distribution of discoid lupus erthematosus?
Dorsal nose and nasal plenum»_space;> pinnae, lips, periocular»_space;> oral mucosa
How should you differentiate circulatory disorders of the skin?
Discrete reddened area -> hemorrhage
Linear pattern
Geometrical shapes
Vascular lesions resulting in ischemia -> degeneration/necrosis
What are the 4 main mechanisms of subcutaneous edema?
Increased hydrostatic pressure (eg. congestive heart failure)
Decrease oncotic pressure
Increased vascular permeability
Lymphatic obstruction
How can you differentiate between congestion and hemorrhage?
Push on area:
Blanching => congestion
Remains reddened => hemorrhage
What is the cause of multifocal cutaneous ecchymosis hemorrhages?
Primary hemostasis defect
Vasculitis vs thrombocytopenia
Pig
Sharply demarcated geometrical shaped dark red to blue area
Some are firm, dry, sucked, darkened
What is your DDX?
Vasculitis (bacteria, snake bite, drug reaction, secodary to ulceration
Frostbite
Toxins causing extreme vasoconstriction
What is diamond skin disease caused by?
Erysipelothrix rhusiopathiae
What causes the lesions of Diamond skin disease?
Vasculitis/ thrombosis -> infarction -> necrosis of the dermis and epidermis
What is the pathogenesis of purpura hemorrhagica?
Type 3 hypersensitivity immune mediated vasculitis
In a horse you see..
Red or purple macules/patches in the skin or mucous membranes
Purpura hemorrhagica
-> ecchymotic hemorrhage
Strep equi infection
What is the pathogenesis of frost bite?
Formation of ice crystals which disrupt cells -> vasoconstriction and endothelial damage -> reduced blood flow-> thrombosis -> infarction
What is the distribution of frost bite?
Extremities
What is a wheal?
Irregular-shaped area of cutaneous edema; transient, solid elevations
What is the pathological process of a wheal?
Vascular disorder
Who gets urticaria (Hive)
Dogs and horses
What is urticaria?
Localized area of edema involving superficial dermis
What is angioedema?
Localized area of edema involving dermis and subcutis
What is the pathogenesis of urticaria?
Type 1 and 3 hypersensitivity; mast cells degraulation -> focal edema, congestion, and pruritus
What are triggers for urticaria?
Food, drug, antisera, and insect stings
