patho 142 congenital defects of the skin and appendages

epitheliogenesis imperfecta

failure of the squamous epithelium and adnexa of skin and epithelium of oral mucosa in development completely, epithelia of hoof may also be involved

aplasia cutis

other terms for epitheliogenesis

epitheliogenesis imperfecta

congenital inherited defect due to a single autosomal recessive gene, recorded in calves, foals, and piglets

epitheliogenesis imperfecta

due to this congenital defect, epidermis is absent and the underlying tissue is easliy traumatized and infected

hypootrichosis congenita

congenital absence of hair, reported in alll domestic animals, may only present in certain parts of the body

ichtyosis

defect of the skin that resembles scales of fish, the skin consist of large horny plates seperated by deep fissures, affected parts are hairless, common in terriers

atrophy

occurs in old animals due to senility, also due to endocrine disturbances such as hypopituitarism

atrophy

affects epidermis, dermis, and accessory structures. indicators included are dryness of the skin, finely wrinkled and poorly elastic

atrophy

due to this condition, epidermis is thin consisting only 2-3 layers of cells beneath the stratum corneum, rete pegs disappears so that the dermal-epidermal junction is flat

amyloidosis

presence of amyloid deposits in the dermal papilla, around sweat glands and blood vessels

calcification or calcinosis

occurs in dogs and is common in GS called calcium gout

calcinosis circumscripta

calcium gout

tumoral calcinosis

other term for calcification or calcinosis

calcification or calcinosis

causes localized Ca depostion in subcutaneous tissue, tongue, or attached to tendons or joint capsule

calcification or calcinosis

due to the specific mineral deposition, it results to bulging masses or nodules which when cut show white paste-like or chalk-like material

ergotism

results from ingestion of grasses and cereals containing toxic alkaloids produced by fungus claviceps purpurea and claviceps paspali

ergotism

initial lesion include swelling and redness of extremities particularly of hindlegs and appear 1 week after ingestion of toxic alkaloid, can be seen in cattles and pigs

ergotism

can be characterized by ulceration gangrene of the feet and tips of the ears and tails

hyperpigmentation

result of minor and chronic irritation, accompanied by mild hyperkeratosis

hyperpigmentation

there is increased in melanocytes intermixed with basal cells or stratum basale cells

hypopigmentation

may be congenital or acquired, decreased number of melanocytes

albinism

congenital absence linked to hypopigmentation

vitiligo

acquired depigmentation related to hypopigmentation that occurs in sheeps and cattles due to Cu deficiency, idiopathic condition in dogs like rottweiler, GS, collies and belgian sheepdog

acanthosis or hyperkeratosis

frequently seen on pressure points such as elbows of large and harness points in farm animals

acanthosis nigricans

hypertrophy of epidermis, usually symmetrical in distribution affecting skin on ventral surfaces of the body, neck, flanks and inner thigh

acanthosis nigricans

affected skin is hard, rough, and grayish in color with multiple creases and folds, lesions gradually spread to other parts of skin

acanthosis nigricans

affected parts shows an increase in the horny layer (stratum corneum or keratin layer) rete pegs are alsp elongated, glands and hair follicle are atrophic

anagen

catagen

telogen

three stages of hair growth

anagen

period of active hair growth, period of follicular development, majority of hair follicles are in this phase

catagen

transitional phase in three stages of hair growth

telogen

resting or inactive phase wherein no hair growth occurs

alopecia

lack of hair due to cessation of hair growth, may be temporary or permanent (may also because of falling off of hair that is not readily replaced by new ones) reversible or irreversible

endocrine imbalance

bacterial and fungal infection

parasitic infection

chemical and drug induced alopecia

cutaneous diseases

telogen effluvium

frictional and psychogenic alopecia

reversible alopecia is caused by 7 possible factors

telogen effluvium

acute generalized loss of many hairs from telogen hair follicles due to stressors like fever, parturition, shock, and other traumatic episodes

genetic condition (epitheliogenesis imperfecta)

destructive effects of neoplasm and granuloma

physical and chemical agents (cicatrical alopecia)

irreversible alopecia is caused by 3 factors

hypertrichosis or hirsutism

excessive growth of hair, a result of failure of cyclical shedding of hair, common in old horses due to pituitary tumor

hyperhidrosis

excessive sweating observed in horses but rare in other animals, may be localized pathological condition due to injury to perpheral nerve or the spinal nerve, can be generalized and occur in association with acute illness

hyperhidrosis

associated with colic, myopathy, excessive muscular activity, tetanus and excitement

hypohidrosis or anhidrosis

absence of sweating seen in horses and cattle transferred from temperate to tropical climates, skin becomes dry and inelastic

seborrhea

characterized by increased sebaceous secretions, gross lesions have waxy crust of sebum and sweat, cellular debris, serum, and coagulated into scales that coat thickened, folded and fissured skin

seborrhea

due to this condition, there is parakeratosis with infiltration of mononuclear cells, spongiosis of stratum spinosum and vesicle formation

seborrheic eczema

pityriasis

seborrhea oleosa

seborrhea is also called

seborrhea oleosa

excessive oil secretion associated with greasy pig disease for pigs and greasy, brownish-yellow clumps of lipid material that adheres to the skin and hair for dogs

seborrhea sicca

dry and greasy skin and coat but with focal to diffuse accumulations of white to gray non-adherent scales which is common in doberman pinchers, irish setters, GS and dachschunds

dermatitis or eczema

inflammation that may be acute, subacute, or chronic

acute dermatits

dermatits that characterized by exudation with the formation of vesicles, begins with erythema and edema or spongiosis which may enlarge and coalesce to form bullae

chronic dermatitis

dermatitis that is characterized by acanthosis, may also show spongiosis but without vesiculation

chronic dermatitis

in this dermatitis, acanthosis is prominent with irregular areas if parakeratosis altering with areas of hyperkeratosis, with mild to severe inflammatory cells infiltration accompanied by localized alopecia due to atrophy of hair follicles and of secretory glands

bacteria

fungi

ectoparasites

helminth larvae

viruses

causes of dermatits (5)

photodynamic dermatitis or photosensitization

due to deposition of photodynamic agents in the skin, causes included are hepatogenous photosensitization, endogenous photosensitization and exposure to other photodynamic agents like phenothiazine and hypericin

liver disease or hepatogenous photosensitization

dermatitis results from failure of biliary excretion of phylloerythrin

phylloerythrin

a degration product of chlorophyll which is produced in the GIT

endogenous photosensitization or congenital porphyria

dermatits where there is excess porphyrin by-products from hemoglobin synthesis due to the absence of enzyme

phenothiazine

hypericin from the plant hypericum perforatum

phtodynamic agents that cause photodynamic dermatitis

upon exposure to light, toxic oxygen radicals are produced from photoreactive agents deposited on the skin

mode of action of photodynamic dermatitis

erythema and edema

necrosis and ulceration seen on the ears, muzzle, eyelids and face, vulva and teats

severely affects hairless and non-pigmented parts of the skin

lesions seen in photodynamic dermatitis

facial eczema

photodynamic dermatitis is called _______ in new zealand

geeldikkop

photodynamic dermatitis is called _____ in south africa

alveld

photodynamic dermatitis is called ______ in scandinavia

bog asphodel

photodynamic dermatitis is called _______ in scotland

impertigo

superficial pustular dermatitis caused by staphylcocci and streptococci, characterized by vesicles and pustule formation

folliculitis

inflammation of the hair follicle and when sebaceous glands are also involved it results to acne

folliculitis

when this condition leads to suppurative liquefaction or pus formation of the follicular structurem boil or furuncle, clusters or group of furuncles will form carbuncles

carbuncles

clusters or group of furuncles will form this specific clinical sign

dermoid cyst

enclosed by stratified epithelium which are soft, oval, or rounded nodules lying at the junction of the dermis

dermoid cyst

the nodule contains sebum, sweat, exfoliated squamous epithelia and coiled hairs due to the developmental defects and trauma to epidermis

epidermoid cysts

similar to dermoid cyst but cavity is lined by squamous cells without secretory structures and often derived from hair follicles

epidermoid cysts

cysts that can transform into malignant squamous cell carcinoma but most are benign

follicular retention cyts

cyts located in follicles resembling pustules and are seen in localized area of acanthosis and hyperkeratosis affecting the follicles as well as the epidermis

infectious papilloma or warts or verruca

cysts consist of papillary, cauliflower like structures on the skin due to a filterable virus (papilloma and poxvirus)

infectious papilloma

appearance of this cyst is due to hyperplasia of the epidermis are roughly keratinized

equine sarcoid

cyst similar to but larger than warts but not horny

equine sarcoid

cysts occur on base of ear, neck, and lower limbs, affected parts may be ulcerated and hairless, recur after excision

equine sarcoid

there is hyperplasia of epithelia with elongation of epidermal or rete pegs into the underlying connective tissue

equine sarcoid

resembles fibroma and neurofibriosarcoma

neoplasia

malignant neoplasia of skin include squamous cell carcinoma, basal cell carcinoma and melanoma