Layers of keratinization
- keratinized squames
- granule cell layer
- prickle cell lalyers
- basal cell laer
- basal lamina
Cornification
- formation of cornified envelope
- synthesis of keratohyalin
- formation of lamellar bodies
- keratinization
*takes about 21-22 days
Hormonal regulation of sebum production
- increased by androgens, thyroid and progesterone
- decreased by corticosteroids, estrogens, suppressing adrogens
Sebum productions and dietary influence
- fat deficiency
- initial dec then inc in sebum production
- most dogs need a combo of saturated and unsaturated fats
- low levels of vitamin A
- dec sebum production….?
Sebum composition
- sterol
- diester waxes
- free cholesterol
- triglycerides
- fatty acids
Seborrhea sicca
- excessive scale formation (dry skin)
Seborrhea oleosa
- Excessive secretion of grease on skin and hairs
seborrheic dermatitis
- excessive presence of scales or grease with inflammation
Primary seborrhea
- american cocker
- english springer spaniel
- inherited dz
- CS may be from birth
Secondary seborrhea
- Internal or external stimuli (Inflammation)
- altered epidermal proliferation, differentiation and desquamation (cornification)
pathogenesis of seborrhea
- inflammation
- histamine
- cytokins
- LTB4 and PGE2
- Endocrinopathies
- hormones
- Nutrition
- glucose proteins
- fatty acids
- vitamins, mineral
- Environment
- bathing
- lipids/water
Clinical signs
- Seborrhea sicca
- Seborrhea oleosa
- Seborrheic dermatitis
- Ceruminous otitis
- Secondary infestations
Primary causes Seborrhea
- idiopathic
- zinc responsive dermatitis type 1
- schnauzer comedo syndrome
- Epidermal dysplasia
- Vitamin A responsive seborrhea
Secondary seborrhea
malassezia dermatitis
TX primary idiopathic seborrhea
Topical
Systemic
- Topical
- keratolytic/keratoplastic shamppos
- antimicrobial shampoos
- Systemic
- oral retinoids
- fatty acids
- antimicrobials
Zn responsive dermatosis
Primary
- breeds
- alaskan malamute, husky, samoyeds
- pathogenesis
- inherited inpairment to metabolize zn
- CS
- age 1-3 years old
- erythema, alopecia, crust, scales, hyperkeratotic foot pads
- mucocutaneous junctions of face
- malassezia and back infections common
Zn responsive dermatosis
Type II (Secondary)
- Breeds
- rapidly growing large breeds
- Pathogenesis
- nutrition
- CS
- thick, well demarcated plaques and crusts
- periocular and perioral areas and genitalia
- malassezia and bacterial infections common
Zn responsive dermatosis
TX
Topical
Systemic
- Topical
- kertolytic/keratoplastic shampoos
- antimicrobial shampoos
- Systemic
- Zn supplement
- antibiotics, antifungals
Schnauzer comedo syndrome
- Breed
- schnauzer
- pathogenesis
- unknown
- CS
- multiple comedones on dorsal midline
- alopecia, erythema, crusted papules, follicular cysts
- secondary infections
Schnauzer comedo syndrome
TX
Topical
Systemic
- topical
- karotolytic/keratoplastic shampoos
- antimicrobial shampoos
- systemic
- oral retinoids (helps with kertinization)
- antimicrobials
Malassezia spp
- broad based
- M. pachidermatis
- Commensal of skin and ears
- inc numbers in humid and warm conditions
- secondary to other dz
- malassezia hypersnesitivity
Malassezia spp has a commensal relationship with….
Staphylococci
Malassezia spp
Predisposing factors
- humidity
- breed
- barrier changes
- malassezia (unlike Candida) not subject to inhibitory effects of bacteria
Yeast numbers do not always relate to….
severity of clinical signs
malassezia Clinical presentation
- Pruritus/erythema
- scaling/seborrhea
- paronychia
- lichenification/hyperpigmentation
- ventral body
- neck, axillae, abdomen
- face/ear pinnae
- feet/forelegs
- skin folds
- otitis externa/media
malassezia dx
- swabs
- tape
- impression smear
*fix sample to remove some fat….
Topical tx
seborrhea sicca
- moisturizing
- emollient vs. humectant
- hypoallergenic
- oatmeal and lanolin
- sulfur +/- salicylic acid
- antimicrobial
Topical tx
Seborrhea oleosa
- selenium sulfate
- sulfur +/- salicylic acid
- Tar
- Benzoyl peroxide
- Antimicrobial
Keratoplastic
- dec DNA => dec mitosis => dec cell ontogenesis
Keratolytic
- dec cohesion between corneocytes => inc desquamation
Emollient
- Moisturize skin => dec TEWL (trans epidermal water loss)
Humectant
- moisturize the skin => dec TEWL and recall water from dermis and environment
- more powerful than an emollient
Benzoyl peroxide
- Keratolytic: benzoic acid
- Antibacterial
- no antifungal
- degreasing
- aggressive => irritant
- bleaching agent
Selenium sulfate
(selsun blue)
- Keratolytic: dec hydrogen bonds between keratines
- Keratoplastic: dec cellular turn-over
- Degreasing
- Antifungal: Malassezia
Sulfur
- Keratolytic: hydrogen sulfate
- Keratoplastic: interaction with cysteine in keratinocytes
- Degreasing
- Antimicrobial and antiparasitic
- pentatonic acid and hydrogen sulfate
- antibacterial and antifungal
*DOES EVERYTHING!!!!
*STINKS
Salicylic
also selsun blue….?
- Shampoo 0.1-2%
- Keratoplastic
- Antipruritic
- Bacteriostatic
- Shampoo 3-6%
- keratolytic
Sulfur + salicylic acid
Synergistic action
Tar
- shampoo
- keratolytic
- keratoplastic
- degreasing
- side effects
- malodourous
- Irritant and pohtosensitizing
- carcinogenic
Emollients
- Mainly oils
- vegetable oils
- animal oils
- silicon, waxes and hydrocarbons
- apply after shampoo
Humectants
- Hygroscopic agents
- propylene glycol
- Glycerin
- Colloidal oatmeal
- Urea
- Sodium lactate
- Lactic acid
*Colloidal oatmea
Phytosphingosine
- Shampoos, lotions, etc
- Pro-ceramide: naturally present in skin
- Anti-inflammatory
- Antimicrobic
Miscellaneous
- Zinc gluconate
- anti-seborrheic
- inhibitor of 5alpha-reductase
- dec sebum production
- Vitamin B6
- dec syndergistically with Zn
- Essential fatty acids
- dec TEWL
Novasomes and spherulites
- nano particles
- adheres to skin and hairs
- slow release of activ ingredient
Antimicrobial shampoo
summary
- Sulfur
- bacteria
- yeast
- Chlorahexidine
- bacteria only
- Benzoyl peroxide
- bacteria only
- Miconazole
- bacteria
- yeast
- Selenium sulfate
- yeast only
Systemic treatment
- Ketoconazole
- Itraconazole
- Fluconazole
- Terbinafine