Integument

Epidermis

the avascular and waterproof outer protective layer of skin

Dermis

the tough layer of skin that holds blood vessels, hair follicles, and glands

Hypodermis (subcutaneous)

the shock absorbing fat tissue that allows the skin to move freely over muscle and bones

Intramuscular

Injected into the muscle

Subcutaneous

Injected into or within the layer of fatty tissue of the skin

Intravenous

Injection into the veins of the skin within the dermis

Intradermis

Injection directly into the dermis layer of the skin

Paw pads

thick layers of fat and connective tissue, conical papillae cover the entire pad, containing exocrine sweat glands

Digital pad(s)

1

Metacarpal/metatarsal pad

2

Carpal pad

3

Nose (planum nasale)

Abnormalities in its appearance can indicate the presence of certain disease

Ergots

Dark, horny structures found on the legs of horses, ponies, and other equids; found buried in the long caudal hairs of the fetlock; vestiges of the second and fourth digits

Chestnut

Dark, horny structures found on the legs of horses, ponies, and other equid; found on the medial portion of each left at the carpus (knee) of the forelimb and tarsus (hock) of the hindlimb; vestiges of carpal and tarsal pads of the first digit

Primary (guard hairs)

Straight or arched hair; thicker and longer than 2’

Secondary (wool type hairs)

Softer, shorter; wavy or bristled hairs; predominant in wool species (sheep, camelids)

Tactile (sinus hairs)

Probes, feeler hairs; sensory endings; whiskers

Arrector pili muscles

Smooth muscle contracts and pulls hair into an erect position; hair sloped from nose to tail erects in reaction to fear; cold, frightened hair can go beyond the normal implantation angle

Hair follicle

Anchors the hair to the dermis

Hair bulb

Deepest part of the hair follicle, that is expanded

Papilla

Mound of dermal cells that rapidly divide, allowing hair to grow

Anagen phase

Growth phase of the hair in which cells at the papilla are rapidly dividing and pushing dead dermal cells through the layers of the hair root; once it has reached its maximum length the hair enters a resting phase (1)

Catagen phase

Phase of hair growth in which active hair growth stops as the hair follicle shrinks and detaches from its blood supply (2)

Telogen phase

Resting and shedding phase of hair growth (3)

Hair greying

Pigment in the cortex and medulla of the hair shaft gives hair its color; melanocytes and the base of the hair follicle produce melanin; as animals age melanocytes become less active and the hair begins to grey and are lost entirely when white hair is produced

Sebaceous gland

Structure stored inside the hair follicles that manufacture and store sebum (an oily lipid substance); which coats base of hair and skin to trap moisture and help in water repellant

Tail glands

Located at the base of tail for recognition and identifications; oily hairs on the base

Anal glands

Musk glands; expels contents when defecating or scared; utilized for identification and intimidation

Ungual process

Important for maintaining good traction, defense, and catching prey; most cats can retract their claws

Hooves

Horses walk on one digit; have four hooves per foot (only two bear weight); continually grows from coronary band; outerlayers are insensitive

Corium

Underlying sensitive tissue which claws and hooves rest on

Dehorning

Removal of horns to prevent injury to self and other animals; cornium is destroyed

Dew claws

Originated from the remains of digits that have regressed during evolution

Laminar tissues

Suspends the third phalanx (P3) within the hoof of horses