Seborrhea Flashcards
What is the transit time for normal keratinization?
- 21-22d for a cell to migrate from the basal layer to but not through the stratum corneum
What things alter/control sebum production and composition?
- hormonal regulation
- dietary influence
Define seborrhea
- term used to indicate crusting
- secca (dry)
- oleosa (greasy)
- primary - also called primary dz of keratinization
- secondary - most common case, many causes
Describe idiopathic familial seborrhea (primary seborrhea)
- presumably genetic keratinization defect
- affect body folds (lip, neck, antecubital, axilla, inguinal, interdigital, etc)
- predisposed breeds: cocker spaniels, springer spaniels, labradors, westies, GSD, basset hounds, doxys, schnauzers
What are some vitamin and mineral-related dermatoses resulting in seborrhea?
- Vitamin A responsive dermatosis
- Zinc responsive syndrome (Huskies)
What are you looking for on a biopsy when you suspect seborrhea?
- hyperkeratosis
- parakeratosis, esp follicular
What is ichthyosis?
- genetically inherited dz of keratinization
- crusting may be present at birth
- described in several breeds
What is an example of a secondary cause for seborrhea keratinization disorders?
- Endocrine disorder - e.g. hypothyroidism
- signs might include follicular atrophy and keratosis, sebaceous atrophy, and epidermal atrophy
- Environmental
- Lipid abnormalities: diet, pancreatic insufficiency, liver dz, malabsorption, other systemic dz
- Neoplastic: mycosis fungiodes
- Pruritic:
- allergies: food, atopy
- infections: bacterial, yeast (Malassezia dermatitis)
- parasites: Demodex
Describe Malassezia dermatitis
- Pathogenesis:
- saprophytic, monopolar yeasts that are lipophilic
- they colonize the skin and mucocutaneous regions of normal pets
-
Malassezia has symbiotic relationship w/ Staph
- mutually beneficial growth factors, no dependency
- dermatitis usually secondary to other dz
- does not invade the skin
- symptoms assoc. w/ organisms may be related to hypersensitivity
What are some general facts about yeast?
- causes odor as a result of metabolism w/ surface lipids
- certain breeds seem predisposed to large #s of yeast and pathology assoc. w/ yeast
- yeast #s do not always seem directly related to severity of signs
What are predisposing factors for Malassezia dermatitis?
- high environmental humidity
- skin folds
- breed predisposition
What are some underlying diseases or problems that may predispose an animal to Malassezia dermatitis?
- host immunity alteration - hypersensitivity esp (atopy)
- endocrinopathy/seborrhea/chronic inflammation
What are clinical signs of Malassezia dermatitis in dogs?
- intense pruritus
- not responsive to steroids
- alopecia
- papules
- lichenification
- hyperpigmentation
- scaling (seborrhea)
- greasy
- dry
- rancid odor
- distribution of lesions: muzzle, chin, pinnae and ear canal, feet, perilabial, perineal, ventral neck, axillae, groin, skin folds
Describe Malassezia infections in cats
- chin acne
- facial dermatitis
- generalized
- look for underlying immune suppression
How do you diagnose Malassezia dermatitis?
- C/S
- cytology
- tape
- dry scrapings
- swabs
- magic #?
