Equine Pathology Workbook

Cyst

A cyst is a fluid, air or semi-solid matter filled sacs, which is lined with cells that are producing the fill material. A sebaceous cyst forms in the upper regions of a hair follicle where the sebaceous gland is located. It is filled with .

Urticaria

Urticaria is also known as “wheals” or “welts”. They are lived and transient. They appear as poorly defined areas of elevated, inflamed skin. Urticaria can be due to allergic reactions, trauma, bug bites, systemic disease or other irritation.

Vesicles

Vesicles are elevated circumscribed collections of

, less than 1 cm in diameter.

Bullae

Bullae are vesicles greater than 1 cm in diameter.

Pustules

Pustules are vesicles/bulla filled with

material.

Crust

Crust is serum, blood or pus mixed with epithelial debris and dead pathogens. It is scabby in appearance though it may ooze at the center of the lesion. Crust is usually the result of a ruptured vesicle/bullae/pustule.

Scales Scales are the

of the stratum corneum. It is dry, flaky and white in

appearance. Scales are often seen with papules and plaques.

Fissures Fissures are also known as “

”. They are linear cracks in the epidermis/dermis

and are usually seen on the back of the pastern and the coronary areas.

Excoriation/Erosion

Excoriation refers to the mechanical abrasion of the skin. It is usually self-inflicted through .

Ulcers

Ulcers are

through the epidermis. They may be due to ill fitting tack and

are also seen on mucous membranes.

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