ANEQ 102: Introduction to Equine Sciences - Laboratory Terms & Concepts

Comprehensive vocabulary flashcards covering equine anatomy, breeds and disciplines, handling, tack, reproductive biology, coat colors, clinical health parameters, nutrition, exercise physiology, and hoof care.

Equine skeletal system bone totals and skull composition

The skeleton contains $205$ bones in total, $34$ of which are flat bones joined by sutures to form the skull.

Equine vertebral formula and anatomical origin of the withers

$\text{7C 18T 6L 5S 15-21Co}$ (7 Cervical, 18 Thoracic, 6 Lumbar, 5 Sacral, and 15–21 Coccygeal vertebrae). The withers are specifically formed by the tall dorsal spinous processes of the $4^{\text{th}}$ and $5^{\text{th}}$ thoracic vertebrae.

Equine thoracic rib cage architecture

Consists of $18$ pairs ($36$ total ribs): the first $8$ pairs are true (sternal) ribs attached directly to the sternum, while the remaining $10$ pairs are false (asternal) ribs connected via costal cartilage arches.

Equine foreleg attachment to the axial skeleton

The forelimb lacks any bony articulation or collarbone (clavicle) connecting it to the torso; it is suspended entirely by a muscular sling (synsarcosis), making scapular conformation critical for absorbing concussion.

Scapular angle and functional locomotion

The slope and length of the shoulder directly determine stride length and range of motion; an upright shoulder produces a short, jarring stride, whereas an angled, sloping shoulder allows maximum forward reach.

Equine carpus (knee) anatomy

Analogous to the human wrist, composed of $7\text{ to }8$ small bones aligned in two horizontal rows that form three distinct joints: the radiocarpal, intercarpal, and carpometacarpal joints.

Equine splint bones anatomical location

Vestigial second ($2^{\text{nd}}$) and fourth ($4^{\text{th}}$) metacarpal or metatarsal bones positioned on the medial ($2^{\text{nd}}$) and lateral ($4^{\text{th}}$) aspects of the large third ($3^{\text{rd}}$) cannon bone.

Equine fetlock joint and proximal sesamoid function

Formed by the junction of the third metacarpal/metatarsal (cannon) and the proximal phalanx (P1 / long pastern). Two caudal proximal sesamoid bones act as a pulley system, protecting passing flexor tendons and augmenting mechanical leverage.

Distal phalanx (P3 / Coffin bone) internal relationships

The terminal pedal bone entirely encapsulated within the hoof capsule; articulates proximally with the second phalanx (P2 / short pastern) and palmar/plantar-distally with the distal sesamoid (navicular bone).

Equine pelvic and hind limb bone articulations

The pelvis (ileum, ischium, pubis) articulates with the femur via a ball-and-socket hip joint; the distal femur articulates with the tibia and patella to form the stifle joint (analogous to the human knee); the tibia articulates with $6$ tarsal bones in $3$ rows to form the hock.

Solar surface structures of the equine hoof

Composed of the outer hoof wall, the sensitive white line (stratum internum junction), the concave weight-bearing sole, triangular shock-absorbing frog with central and collateral sulci (commissures), and supporting bars.

Equine digital soft tissue structures (Sagittal cross-section)

The dorsal common digital extensor tendon, superficial digital flexor tendon, deep digital flexor tendon (inserting on the solar surface of P3), navicular bursa, navicular bone, and shock-absorbing fibroelastic digital cushion.

Chronological evolution of the horse genus

1. Eohippus (Dawn Horse, $60\text{--}45\text{ million years ago}$, small 4-toed browser)
2. Miohippus ($36.9\text{--}20.5\text{ million years ago}$, 3-toed)
3. Merychippus ($20.43\text{--}10.3\text{ million years ago}$, high-crowned grazing teeth)
4. Pliohippus ($5.3\text{--}2.6\text{ million years ago}$, first monodactyl single-toed ancestor)
5. Equus ($\approx 4.8\text{ million years ago}$, modern horse).

Reining maneuver composition and requirements

A western discipline judged on executing precise patterns including slow small circles, fast large circles, flying lead changes, rollbacks over the hocks, in-place $360^\circ$ spins, and prolonged sliding stops, showcasing willing guided control.

Cutting competition performance criteria

Horse and rider enter a herd, quietly cut an individual cow, drive it into the center of the pen, and drop rein contact so the horse independently uses instinctual 'cow sense' to block the animal from returning to the herd.

Western pleasure evaluation focus

Judged at the walk, jog, and lope on calm disposition, consistent tempo, responsiveness, cadence, level topline, and balanced, relaxed gaits suitable for a comfortable ride.

Classical dressage definition and governing rules

Derived from the French word for 'training' and governed by the FEI as the highest expression of horsemanship, wherein horse and rider perform predetermined tests from memory demonstrating balance, suppleness, collection, and precision.

Eventing (Combined Training) three competition phases

A comprehensive military cavalry-derived equestrian test comprising: 1. Dressage (harmony and obedience), 2. Cross-Country (endurance, speed, and jumping solid natural obstacles), and 3. Stadium Show Jumping (athleticism and stamina over knock-down fences).

Equine visual field dimensions and blind spots

Monocular vision spans $190^\circ\text{--}230^\circ$ per side with minimal binocular overlap ($60^\circ\text{--}70^\circ$) directly ahead; two distinct blind zones occur directly under the nose ($\approx 6\text{ ft}$ forward) and directly behind the hindquarters/tail ($\approx 6\text{ ft}$ backward).

Corpus callosum functional limitations in horses

The neural tract connecting the left and right cerebral hemispheres has limited cross-hemispheric communication; visual stimulus processed in one eye is not automatically integrated by the contralateral side, requiring independent bilateral desensitization and training.

Equine ear positions and behavioral diagnostics

• Pricked stiffly forward: Alert, focused on external stimuli
• Flopped laterally ('airplane ears'): Fatigued, depressed, or sedated
• Angled backward toward rider: Attentive, listening to verbal/seat cues
• Pinned flat back against the neck crest: Aggressive, angry, preparing to bite or kick.

Equine behavioral snapping (Champing)

A submissive behavioral display common in foals and young horses directed toward dominant herd members, characterized by extending the neck, retracting the lips, and rhythmically opening and closing the jaws without making contact.

Flehmen response physiological mechanism

The horse curls its upper lip, elevates the head, and draws scent compounds through specialized nasopalatine ducts into the vomeronasal organ (Jacobson's organ) on the hard palate to analyze pheromones (such as estrus markings) and novel odors.

Safe physical approach and handler blind-zone management

Never approach directly from behind; cluck or speak to gain auditory attention, approach obliquely toward the shoulder/throat area, and keep a resting hand along the hindquarters when moving closely behind to reduce kick impact force.

Do not kneel or sit, aways crouch to get away if need, face horse tail, run hand down the back of leg to show that you are there

Lower limb handling and hoof picking safety protocol

Safe tying height and line mechanics

Tie horses at wither height or higher with approximately an arm's length of slack; higher ties prevent the horse from placing downward leverage against its cervical vertebrae or poll if it pulls back, significantly lowering spine fracture risks.

Quick release knot structural purpose and function

A safety knot that withstands horizontal tension and pull from the horse while permitting the handler to instantaneously free the animal during panic or entrapment by pulling the single working tail.

Snaffle bit mechanical action

A non-leverage bit operating on direct $1:1$ pressure ratio with reins attached directly to the mouthpiece rings; applies pull to the corners of the lips, tongue, and interdental bars without poll leverage.

Curb bit mechanical action and leverage ratio

A shanked leverage bit employing class $2$ lever principles; rein pressure pivots around the mouthpiece fulcrum, transmitting multiplied leverage forces onto the bars, tongue, chin groove (via curb strap/chain), and poll.

Curb strap width and angle adjustments

Must be at least $0.5\text{ inches}$ ($1.27\text{ cm}$) wide to lie flat without pinching; adjusted so that it engages and tightens against the chin groove when bit shanks rotate backward to an angle of $45^\circ\text{--}50^\circ$.

Pelham bridle configuration and rein separation

An English bridle operating a single integrated leverage bit fitted with two separate pairs of reins: an upper direct snaffle rein (mouthpiece corner pressure) and a lower curb rein (shank leverage on poll and chin groove), controlled alongside a curb chain.

Weymouth bridle (Full bridle) component assembly

A double bridle featuring two separate bits and headstalls: a small snaffle (bridoon) resting above on the lip corners, and a lower curb bit (Weymouth) with shanks, supported by two reins, a flat curb chain, and an anchoring lip strap.

English cavesson noseband fit specifications

Positioned approximately two fingers' width below the facial crest/cheekbone, adjusted loose enough to fit two stacked fingers flat between the leather strap and the nasal bone to prevent restriction of breathing or jaw motion.

Western bitless hackamore varieties (Bosal vs. Mechanical)

• Bosal: A braided rawhide or leather noseband loop tied with a mecate rope that applies mild direct pressure to the nasal bridge and chin without mechanical leverage.
• Mechanical Hackamore: A leverage-inducing noseband with shanks and a curb strap that applies severe multiplied pressure across the nose bridge and chin groove.

Western saddle gullet clearance and tree fitting

The saddle tree must fit the angle of the withers and back musculature; adequate padding must maintain vertical space such that the handler can easily slide $2\text{ to }3$ fingers between the horse's withers and the saddle gullet under full rider weight.

Specialized western saddle modifications (Roping vs. Cutting vs. Barrel)

• Roping: Heavy tree, thick reinforced horn wrapped for dallying, low cantle, slick fork for fast dismounts.
• Cutting: Flat seat, high pommel with slim horn, wide swells, and freely swinging fenders for deep athletic turns.
• Barrel: Lightweight, tall horn, wide swells, deep seat pocket, and high cantle for rider security during abrupt turns.

Specialized English saddle flap profiles (Dressage vs. Close Contact)

• Dressage: Straight, long flap with prominent knee blocks supporting a long, vertical leg position and deep balanced seat.
• Close Contact (Jumping): Forward-cut flap with low pommel and flat seat accommodating shortened stirrups and a forward two-point jumping position.

Equine cervical changes: Estrus vs. Diestrus

• Estrus (Estrogen dominant): Pink, highly vascular, flaccid, and relaxed resting flat on the vaginal floor, producing thin, clear, watery mucus.
• Diestrus (Progesterone dominant): Pale, tightly constricted, upright, projecting into the vagina, and sealed with thick, sticky mucus.

Unique structural inversion of the mare ovary

Unlike other mammals, the mare's ovary is structurally inverted: the steroidogenic and gametogenic cortex is positioned internally, while the vascular and connective tissue medulla lies on the outside.

Ovulation fossa functional anatomy

A distinct, narrow concave depression on the ventral border of the ovary where cortical tissue reaches the exterior; represents the sole physiological point through which mature oocytes can ovulate into the infundibulum.

Equine oviduct regional divisions and fertilization site

Composed of the infundibulum (fimbriated catcher's mitt over the ovulation fossa), the ampulla, and the narrow isthmus. Fertilization takes place specifically at the ampullary-isthmic junction before the embryo travels to the uterine horn.

Clinical criteria for breeding an estrous mare

1. Must be on the $3^{\text{rd}}$ day of estrus OR exhibit a dominant follicle measuring $\ge 30\,\text{mm}$ on transrectal ultrasound.
2. Must exhibit an open, relaxed cervical canal. When met, insemination occurs every other day until ovulation is verified.

Anatomical structures of the stallion penis during erection

Erectile tissue expands the root, shaft (body), and glans penis (collum glandis, corona glandis, and protruding urethral process); during full engorgement, penile length and girth double, while the glans expands by $3\text{ to }4$ times its flaccid dimensions.

Stallion scrotal width diagnostic significance

Measured with calipers across the widest non-erect scrotal plane; scrotal width correlates directly with total functional testicular volume, daily sperm production ($\text{DSP}$), and total potential sperm output.

Artificial vagina (AV) physical parameters for stallion collection

Must replicate natural mating through three parameters: internal temperature using hot water at $130^\circ\text{F}$ ($55^\circ\text{C}$), adequate pneumatic/water pressure, and non-spermicidal sterile lubrication (such as K-Y Jelly).

Three cardinal semen evaluation parameters

1. Volume: Gel-free semen volume measured in a pre-warmed graduated cylinder ($\text{ml}$.
2. Motility: Measured via microscope or Computer Assisted Semen Analysis (CASA) for Total Motility and Progressive Motility ($\%$).
3. Concentration: Sperm cell density measured using a calibrated densimeter/photometer in $\text{million/ml}$.

500 × 10 to the power of 6 divide by concentration x progressive motility = ml of raw semen per does

.Equine fresh insemination dose algebraic formula

Equine semen extension dilution rules

Raw semen must be diluted with pre-warmed commercial extender at a minimum ratio of $1:1$ ($\text{vol:vol}$), and the final combined breeding volume must measure at least $10\,\text{ml}$ total before uterine infusion.