dental anatomy
suited for eating grass
- enlarged premolars continuous with molars make large grinding surface
- cheek teeth (pre/molars) and incicsors have high crowns to accommodate attrition
- delayed formation of roots allow teeth to grow for years
- attrition is about 2-3mm per year
- enamel, strongest casing is folded to increase SA for grinding
infundibulm
folds of enamel and dentine, makes teeth stronger and greater surface area for grinding
buccal surface and permanent detention
3-1-3(4 top)-3
- occlusal plane angled
- maxilary teeth wider with more folding
- occlusion is in narrow area between lingual edge of upper and buccal edge of lower
position of teeth over time
association between teeth and maxillary sinus changes
- sinus increases
- teeth move forward and are extruded
- remove teeth and you’ll have access through bone or sinus
desciduous incsiors
think baby teeth, fall out
aging
based on tooth eruption dates, appearance of occlusal surface of lower incisors
-accurate up until 8 years
floating teeth
- irregular or incomplete chewing may cause buccal edge of upper and lingual edge of lower to escape wear
- results in sharp edges which must be filed down (floated) to prevent injury to cheeks and tongue and allow better chewing
gutteral pouch
- side of head, between eye and ear
- diverticulum of auditory tube
- several cranial nerves and arteries run through
- drains ventrally into pharynx
- FUNCTION: mechanism for COOLING cerebral blood supply through trasnfer from carotid to air
gutteral pouch blockage
- drainage can be blocked and accumulate, results in swelling behind jaw, nasal discharge
- other signs=inflammation of middle ear, epistaxis (nose bleeds from carotid artery), swallowing difficulties (nerve damage), drooping of ear, sweating of neck, pupillary constriction (facial nerve damage)
- can get infected
- examined with endoscope via nasal passage
- enter pouch to drain via Vibord’s triangle
larynx
suspended by hoid apparatus, made of cartilages forming passageway to trachea
left laryngeal hemiplagia
sound on inspiration caused by flow of air vibrating lax vocal fold
- laxity of fold from paralysis of muscles that keep passage open during inhalation
- almost always LEFT side
- problem with left recurrent nerve
- more common in larger horses
forelimbs
carry 55-60% of weight at rest
- main shock absorbers at faster gaits
- hind limbs main propulsion
- can shift weight: raise head shortens neck and displaces gravity to rear (therefore lame horses lift head when painful forelimb place on ground and lower when sound limb bears weight)
conformation of limbs
straight when view from front
- mostly straight from side view
- slope of fetlock should parallel digit
forelimb bones and joints, top to bottom
scapula, shoulder joint, humerus, elbow, ulna and radius, 3 carpus joints, carpal bones, splint bone, metacarpal, fetlock joint (good flexion and extension), proximal sesamoid bones, proximal phalanx bone, pastern joint, middle phalanx bone, coffin, distal phalanx/hoof
coffin bone
- inside hoof, conforms to hoof shape
- attaches to hoof wall via dermis
- porous to allow blood vessels through to overlying dermis
white line
junction between sole and wall (outer part of hoof) on the hoof
hoof anatomy and trauma effects
-protected by modified dermis
wall grows from epithelium covering coronary dermis
-horn tubules embedded in horn and slides over dermis covering coffin bone
-trauma to coronary dermis causes horn defects that take 8 months to reach the ground
hindlimb bones
pelvis, humerus, fibula, dibula, metatarsal 4(splint bone), metatarsal 3 (cannon bone), proximal sesamoid bones, proxial middle and distal phalanges
hindlimb joints
stifle/knee joint, tarsus/hock, fetlock, pastern, and coffin joints (same as forelimb)
stomach
small: 5-15 litres
- mostly takes up left half of abdomen
- cardiac sphincter between esophagus and entry to stomach makes vomiting rare
small intestines and illness
duodenum-bile and pancreatic ducts empty
-then jejunum, then ileum
-total length 25 m
attached to mesentery but mostly freely mobile, can get stuck, causing strangulation of tissue or obstruction of intestine
large intestine
- cecum=30 litres, blind sac for microbial fermentation
- colon-ascending, transverse, and decesnding
- predisposed to various forms of obstruction and displacement
3 flexures of colon
180 degree turns, reduces diameter and decreases fluids in disgesta through reabsorption
-can result in impactions though
