L1-congenital, epidermal differntiation, and pigmentation disorders Flashcards
epidermis
stratified squamous.
Dermis
Adnexa-hair follicles
subcutis
adipose tissue- hypodermis
congenital
present at birth- not all are hereditary
hereditary
not always present at birth
EX: color dilution alopecia
not all are congenital
Ichthyosis
hereditary/ inherited
various dogs, cattle
known genetic mutation in some dog breeds
defects in formation of statum corneum
scaling and thickened skin
diagnosis: skin biopsy
Ichthyosis fetalis
cattle: more severe, still born cattle
ichthyosis congenita
cattle: not as severe
Epidermolysis bullosa
red foot disease
defects in the basement membrane of the epidermis
defect in proteins between dermis and epidermis
clefts and vesicles where epidermis meets dermis
skin and mucous membrane blistering and ulceration from minor trauma
oral mucosa, lips and extremities
hooves, pads, claws can slough off
cattle, sheep, goats, horses, dogs
Epitheliogenesis imperfecta
Aplasia cutis
failure of statified squamous epithelium to completely develop
sharply demarcated areas without epidermis
face, extremities, mucous membranes
Hereditary Zinc deficiency
occurs in cattle and bull terrier dogs
autosomal recessive- hereditary
multi-systemic disease with skin lesions
crusting mainly on face and distal limbs with dry, flaky skin
Hereditary zinc deficiency in cattle
lethal trait A46; defect in intestinal malabsorption
die due to immune dysfunction, thymic hypoplasia- more prone to infection
hereditary zinc deficiency in dogs
lethal acrodermatitis of bull terriers
doesn’t respond to supplementation
Hereditary zinc deficiency on biopsy
diffuse parakeratotic hyperkeratosis
Hereditary zinc deficiency image
congenital hypotrichosis/alopecia
lack of hair where it should be present
reported in many domestic animal species
most common in calves
can be purposely bred- chinese crested, mexican hairless pig, sphix
need to distinguish form non-genetic causes
maternal iodine deficiency
intrauterine infection with bovine viral diarrhea or classical swine fever
samples: most alopecic and most haired from similar anatomic locations
congenital hypotrichosis/ alopecia
Hypertrichosis
excessive amount of hair
-rare
cattle friesian cattle, hereditary
lambs- border disease infection in utero
hairy shaker disease
long, course hair and clonic- tonic spasms of tremors
Dermatomyositis
disease of dogs
hereditary in collies, shelties
pathogenesis is unknown
idiopathic inflammatory disease of skin and muscle
Dermatomyositis
ischemic dermatopathy
small pustules, and vesicles, progress to ulcerations with alopecia
eventual scarring
pinnae, bridge of nose, lips, periocular skin, tip of tail
likes to target face and capillary walls
Hereditary collagen dysplasia
dermatospraxis, ehlers-danlos syndrome, cutaneous asthenia
reported in most domestic animals-rare
skin stretches and tears easily
defect in enzymes involved in collagen synthesis or processing
skin tears easily and is hyperestensible/loose
minimal hemorrhage
Hereditary collagen dysplasia
HERDA- hereditary equine regional dermal asthenia
hereditary in quarter horses- especially elite cutting horse lines
genetic test availabe
Dermatosis vegetans
inherited disease of pigs
Landrance breed
vegetating skin lesions, hoof malformations, giant-cell pneumonia
start on ventral abdomen and medial thighs-expand to cover all skin
erythematous papules- crusty lesions with a brown-black color and central depression
if pigs survive, lesions start to resolve
Epidermal differentiation
top layer of skin/ satisfied squamous
Keratoses
firm, elevated areas of excessive keratin production
Equine linear alopecia- linear keratosis
many breeds, quarter horses predisposed
vertically oriented linear areas of alopecia, crust and scaling
shoulder, neck lateral thorax
Equine cannon keratosis-stud crud
vertically oriented areas of alopecia, scaling, and crusting on cranial surface of rear cannon bones
not itchy or painful
Sebaceous Adenitis
disease of dogs
standard poodle is predisposed
destruction and loss of sebaceous glands around hair follicles - antimicrobial protection
symmetrical alopecia with broken hairs
brown to yellow follicular casts
often have secondary bacterial infection
Vitamin A responsive dermatoses
Nearly exclusively in cocker spaniels
not a true vitamin A deficiency levels normal
Does NoT respond to vitamin A treatment
- Hyperkeratotic plaques with follicular
externa
plugging on ventral and lateral chest and abdomen
• Greasy hair coat with ceruminous otitis
Exfoliative dermatoses
lots of scaling, crusting, and erythema
can be localized or generalized
usually associated with another disease
thymoma, epitheliotropic lymphoma, drug reactions
Hyperplastic dermatosis of Westies
West highland white terriers
SEVERE skin disorder, usually a manifestation of allergic skin disease
erythema, scaling, pruritus-trunk, axillary and inguinal regions
chronic cases- skin becomes lichenified, hyperpigmented
-armadillo westie syndrome
Equine coronary band dystrophy
proliferation and hyperkeratosis of epidermis of coronary band- thickened
chestnut and ergots can also be affected
coronary band is thicked -crusting, scaling
hoof wall often abnormal
Pigmentary disorders
disorder of melanin
Melanin
synthesized by melanocytes
requires tyrosine and tyrosinase- rate limiting enzyme, critical
also require copper- deficient/ then deficient in ability to produce melanin pigment
after production, melanin transferred to nearby epidermal cells
melanosomes
membrane bound organelles that make melanin within melanocyte
Leukoderma
reduced pigment in skin
Leukotrichia
reduced pigment in hair
Focal macular melanosis
lentigo simplex
seen in dogs and cats especially cats that are orange, cream and tri colored
flat, pigmented macules, usually on mucocutaneous junctions of mouth, eye, nose and footpads
clinically insignificant, can be confused for melanoma
sheep- can be seen after sheering
Canine acanthosis nigricans
progressive alopecia, hyperpigmentation, and lichenification of the skin
idiopathic disease, progressive
dachshunds are predisposed - early age of onset
start in axilla, spread to ventral abdomen and inguinal areas
often have secondary bacterial or yeast infections
Acromelanism
Temporary coat color change due to temperature
high temp-light color
low temp- dark color
cats- siamese and himalayan
rabbits and mice
Hereditary hypopigmentation disorders
- Melanocytopenic hypomelanosis
similar to waardenburg syndrome in people
white coats , blue or heterochromatic irises, and are deaf
Vitiligo
biggest one seen clinically
progessively expanding pale macules, often symmetrical
Cyclic hematopoiesis- grey collie syndrome
silver grey hair coat
also causes cyclic neutropenia
Acquired hypopigmentation
-usually secondary to something
secondary to trauma, radiation, infection, nutritional deficiences
horses- onchocerca, culicoides, coital vesicular exanthema
canine uveodermatologic syndrome
artic breeds- akita, husky, malamute
bilateral panuveitis and bilateral cutaneous depigmentation
lips nose periorbital skin- clinically relevant
Hereditary cutaneous Hylaluronsis
Cutaneous mucinosis
• Inherited dermal connective tissue disorder
• Hyaluronic acid is main component
• Overactivation of hyaluronan synthase 2 à large amounts in dermis
• Chinese Shar-Pei dog
• Wrinkled skin appearance
• Also seen secondary to hypothyroidism
• Myxedema in dermis
Hereditary cutaneous hyaluronsis
Cutaneous mucinosis
• Inherited dermal connective tissue disorder
• Hyaluronic acid is main component
• Overactivation of hyaluronan synthase 2 à large amounts in dermis
• Chinese Shar-Pei dog
• Wrinkled skin appearance
• Also seen secondary to hypothyroidism
• Myxedema in dermis
