Flashcards in Equine Physiology Deck (52)
Old dental naming system
Wolf tooth: vestigial
- then number 1-6
- or: PM1 (wolf tooth) - PM4 and M1, M2, M3
Triadan numbering system
*start with central inscisor*
Upper right: 100s (101-111)
Upper left: 200s (201-211)
Lower left: 300s (301-311)
Lower right: 400s (401-411)
What tooth number is the wolf tooth on the upper right side?
What tooth number is the canine tooth on the lower left side?
Herbivores vs carnivores
Grinding vs shearing
- even inscisors are flat in the horse
- grinding high silica content feed wears away teeth
Teeth which have a limited growth period, but prolonged eruption
- seen in horses
Permanent growth and eruption throughout life
- seen in rabbits
Limited growth and limited eruption time
- seen in dogs/cats
Equine teeth go thru contstant wearing away of _______
- pulp cavity constantly retracting
- secondary dentin constantly being laid down to seal pulp cavity
- any malocclusion leads to dental overgrowths --> can impede mastication
What cell type lays down secondary dentin?
- reside in periphery of pulp cavity, but have processes that extend through the dental tubules (3-5 mm)
What are the 3 types of dentin?
Primary: laid down as the tooth forms before it erupts and is in wear
Secondary: continues to form as the occlusal surface is worn away and pulp cavity retracts --> seals off pulp cavity
Tertiary: forms in response to local insults
What is dentin composed of?
- 70% minerals (hydroxyapatite crystals)
- 30% organic components
When do permanent premolars erupt?
- 06s: 2.5 yrs
- 07s: 3 yrs
- 08s: 4 yrs
* all are preceded by a deciduous tooth*
When do molars erupt?
- 09s: 1 yr
- 10s: 2 yr
- 11s: 3.5 yrs
When do the incisors erupt?
- 01s: 2.5 yrs
- 02s: 3.5 yrs
- 03s: 4.5 yrs
* are in wear against the opposite member within 6 months and are preceded by a decidious tooth*
When should all caps be gone?
By 5 years, all teeth should be fully in wear against opposite member
When does root development slow down?
By 7 years, overall length of teeth begins to become shorter
- by 12-15 yrs all development has stopped
Upper arcade is 25-30% wider than the lower
- naturally leads to sloped occlusal surface which increases feed efficiency
- incisors meet, cheek teeth do not!
Where teeth do not meet
- teeth won't wear and will overgrow
- most horses develop points to some degree, leading to poor feed utilization and loss of body condition
Points create _____
- prevented by rasping the sharp edges
- typically occurs in the outer edges of the uppers and inner edge of lowers
Upper arcade is set rostral relative to lower arcade, resulting in rostral aspect of upper first cheeck tooth getting overly long and caudal aspect of last lower cheek tooth doing the same
*want to be careful to not cut off at the pulp cavity!*
Formation of hooks will stretch the jaw out of alignment and create stress on the _____
TMJ = unequal wear on the incisors
- pushes upper arcade even more forward
- rostral 2/3 is striated
- caudal 1/3 is smooth with thicker muscle and a smaller lumen = well developed lower esophageal sphincter
- enters stomach obilquely
Do horses vomit?
No, many horses will rupture their stomach before they regurgitate or vomit
- passing a stomach tube on a colic is life saving
GIT of the horse
Small stomach, long small intestine with a fast transit rate
- fermentation occurs in the colon
- GIT has more nerves than the spinal cord (local enteric nervous system) and lacks a blood barrier
Equine GI volumes
- stomach: 8-15 L (8%)
- SI: 40-60 L (30%) = 70 ft
- cecum: 28-36 L (15%) = 4 ft
- large colon: 80-90 L (38%) = 10-12 ft
- small colon: 16 L (9%) = 10-12 ft
Do horses have a gallbladder?
NO, continuously forage throughout the day so no need for storage
Horses are _______
Non-ruminant herbivores (hind-gut fermenters)
- digest simple carbs and also utilize fibrous sources
Enzymatic digestion occurs in the ___
Foregut ahead of the cecum
- accounts for 52-58% of crude protein digestion, all protein absorption, long chain lipid absorption, and all soluble carb digestion/absorption