Exam 3 – Dr. Brashier Equine GI

Question 1

Do herbivores have grinding or shearing teeth?

Answer 1

Grinding

Question 2

What happens when herbivores grind high silica content feed?

Answer 2

Wears away teeth

Question 3

What are hypsodont teeth?

Answer 3

Teeth which have a limited growth period, but prolonged eruption

Question 4

What happens to odontoblasts in horses?

Answer 4

They remain active throughout the life of the tooth synthesizing regular secondary dentin and also irregular secondary dentin on the periphery of the pulp horn throughout most of the life of the tooth

Question 5

What does the synthesizing of secondary dentin do?

Answer 5

Gradually reduces the size of the pulp cavity and thus of the pulp and eventually fully occludes the pulp horn

Question 6

What are the 3 main types of dentin?

Answer 6

Primary dentin
Secondary dentin
Tertiary dentin

Question 7

What is primary dentin?

Answer 7

Laid down as the tooth forms before it erupts and is in wear

Question 8

What is secondary dentin?

Answer 8

Continues to form as the occlusal surfaces worn away and the pulp cavity retracts so that the secondary dentin seals off the pulp cavity so that it is not exposed as the tooth wears away

Question 9

When is tertiary dentin formed?

Answer 9

In response to local insults

Question 10

Where do odontoblasts reside?

Answer 10

At the periphery of the pulp cavity, but their odontoblast processes extend through the dental tubules

Question 11

What is the bulk of the tooth composed of?

Answer 11

Dentin

Question 12

What is dentin?

Answer 12

A cream colored, calcified tissue composed of approximately 70% minerals and 30% organic components

Question 13

What happens to the pulp cavity?

Answer 13

It is constantly retracting

Question 14

What is secondary dentin doing?

Answer 14

Constantly being laid down to seal pulp cavity

Question 15

When do the permanent premolars erupt?

Answer 15

06s: 2.5 years
07s: 3 years
08s: 4 years

Question 16

When do the molars erupt?

Answer 16

1, 2, and 3.5 years, respectively

Question 17

When do the incisors erupt?

Answer 17

2.5, 3.5, and 4.5 years

Question 18

What should the teeth be like by 5 years?

Answer 18

All caps should be gone and all teeth fully in wear against the opposite member

Question 19

How much do teeth wear away?

Answer 19

2-3 mm/yr

Question 20

What happens at 7 years of age with teeth?

Answer 20

The root development slows and overall length of all teeth begins to become shorter

Question 21

When does tooth development stop?

Answer 21

12-15 years

Question 22

What is anisognathic?

Answer 22

Upper arcade 25-30% wider than lower

Question 23

What does anisognathic teeth lead to?

Answer 23

Naturally leads to sloped occlusal surface, which increases feed efficiency

Question 24

What happens since incisors meet?

Answer 24

Cheek teeth do not meet

Question 25

What are points?

Answer 25

Where teeth do not meet

Question 26

What is the consequence of hypsodont teeth?

Answer 26

Any malocclusion lead to dental overgrowth, which can lead to poor feed utilization and loss of body condition

Question 27

What are ulcers created by points prevented by?

Answer 27

Rasping sharp edges

Question 28

What is the most common malocclusion?

Answer 28

Points

Question 29

What is the second most common malocclusion?

Answer 29

Hooks Having the upper arcade set relative to the lower arcade, which results in the rostral aspect of the upper first cheek tooth having nothing to wear against and subsequently getting overly long

Question 30

What is the rostral 2/3 of the esophagus made of?

Answer 30

Striated muscle

Question 31

What is the causal 1/3 of the esophagus made of?

Answer 31

Smooth muscle

Question 32

What is the lower esophageal sphincter of the esophagus like?

Answer 32

Very well developed

Question 33

Horses do not like vomiting. What will they do before regurgitating or vomiting?

Answer 33

They will rupture their stomach

Question 34

What can be lifesaving with colic?

Answer 34

Passing a stomach tube

Question 35

Which GI tract tends to be more complex, herbivores or carnivores?

Answer 35

Herbivores

Question 36

What is the nervous control of the GI tract through?

Answer 36

Enteric nervous system

Question 37

What is the volume of the stomach?

Answer 37

8-15 L

Question 38

What percentage of the GI tract is the stomach?

Answer 38

8%

Question 39

What is the length of the small intestine?

Answer 39

70 ft.

Question 40

What is the volume of the small intestine?

Answer 40

40-60 L

Question 41

What percentage of the GI tract is the small intestine?

Answer 41

30%

Question 42

What is the length of the cecum?

Answer 42

4 ft.

Question 43

What is the volume of the cecum?

Answer 43

28-36 L

Question 44

What percentage of the GI tract is the cecum?

Answer 44

15%

Question 45

What is the length of the large colon?

Answer 45

10-12 ft

Question 46

What is the volume of the large colon?

Answer 46

80-90 L

Question 47

What percentage of the GI tract is the large colon?

Answer 47

38%

Question 48

What is the length of the small colon?

Answer 48

10-12 ft

Question 49

What is the volume of the small colon?

Answer 49

16 L

Question 50

What percentage of the GI tract is the small colon?

Answer 50

9%

Question 51

Look at GI tract

Answer 51

Look at GI tract

Question 52

What kind of non-ruminant herbivores are horses?

Answer 52

Hind-gut fermenter

Question 53

What is the stomach of a horse like?

Answer 53

Simple stomach that digests simple CHO sources, but can utilize fibrous sources

Question 54

Where does all true enzymatic digestion occur in the horse?

Answer 54

In the fore gut ahead of the cecum

Question 55

What does the enzymatic digestion in the fore gut account for?

Answer 55

52-58% of the crude protein digestion, all protein absorption, all long chain lipid absorption, and virtually all soluble CHO digestion and absorption

Question 56

Where does bacterial or microbial digestion of fiber CHO occur?

Answer 56

In the cecum and colon where large quantities of VFAs are produced through fermentation and absorbed

Question 57

What happens since there is no enzymatic digestion in the large intestine?

Answer 57

All other products of microbial proliferation are lost to the horse

Question 58

What are the 4 major regions of the stomach?

Answer 58

Stratified squamous epithelium, cardiac, fundic, and pyloric

Question 59

What is the stratified squamous epithelium of the stomach like?

Answer 59

Does not contain any glands or mucus producing cell and ends abruptly at the margo plicatus

Question 60

What does the cardiac mucosa contain?

Answer 60

Mainly mucus and bicarbonate producing glands

Question 61

What are the glands in the fundic region responsible for?

Answer 61

Produce some mucus, but primarily responsible for acid and protease production

Question 62

What do the pyloric glands do?

Answer 62

Mucus production (rich in mucus producing glands) Some bicarbonate production Some protease production

Question 63

What breaks down food in the stomach?

Answer 63

Acids and the enzyme pepsin

Question 64

What does pepsin do?

Answer 64

Causes the breakdown of proteins into amino acid chains

Question 65

What is the end product of the stomach?

Answer 65

Food broken down into chyme

Question 66

How much of the digestive system is made up by the stomach?

Answer 66

8-10%

Question 67

How long does it take fluid to move through the stomach?

Answer 67

20-30 minutes

Question 68

How long does it take grain, pellets, and short grass to move through the stomach?

Answer 68

0.5 to 5 hours

Question 69

How long does it take long stem dry hay to move through the stomach?

Answer 69

16 hours

Question 70

When will the stomach empty?

Answer 70

When it is 2/3 full regardless whether full digestion has taken place or not

Question 71

Horses are continuous grazers. What are facts about the horse that pertain to this fact?

Answer 71

Produce acid 24 hours/day regardless No gall bladder Often fed once or twice a day

Question 72

How much of their body weight can horses consume of dry matter?

Answer 72

2 to 2.5%

Question 73

What is the pH of an empty stomach of a horse?

Answer 73

1.5

Question 74

What does forage act as?

Answer 74

Buffer

Question 75

What is the pH of an empty stomach of a carnivore?

Answer 75

6

Question 76

What assists with small intestine with digestion?

Answer 76

Pancreas and liver

Question 77

What does the liver produce?

Answer 77

Bile, which assist with fat absorption by the small intestine

Question 78

How frequently is bile secreted in a horse?

Answer 78

Constantly because there is no gall bladder

Question 79

What does the pancreas secrete?

Answer 79

A mixture containing enzymes and bicarb into the small intestine, which his in breaking down protein and AA chains into individual AA and soluble CHOs into simple sugars

Question 80

What percentage of fat in a diet can horses digest?

Answer 80

15-20%

Question 81

What is the small intestine responsible for?

Answer 81

Secretory H2O Nutrient absorption Rapid transit

Question 82

What are the difference of the small intestine in horses compared to small animals?

Answer 82

The proximal half is more secretory than absorptive for water Even though the SI is long, the rate of passage is relatively fast

Question 83

How much of the horses total body water circulates through the GI tract on a daily basis?

Answer 83

1/2

Question 84

What is cellulase?

Answer 84

Microbial enzyme to break down fermentable fiber into simple sugars

Question 85

What is acetic acid?

Answer 85

Can be used directly by mammalian cells or used by the liver for synthesis of longer chain fatty acids for formation of triglycerides Directly accounts for 30% of energy needs

Question 86

What happens with propionic acid?

Answer 86

Goes to liver for glucose synthesis

Question 87

What is butyric acid used by/?

Answer 87

Colonic cells

Question 88

What do proteases do?

Answer 88

Breakdown plant protein into peptides | Take in and converted into microbial protein

Question 89

What is within the anaerobic fermentation vat?

Answer 89

VFAs | Some water soluble vitamins

Question 90

How much do VFAs account for energy needs?

Answer 90

50-80%: 30% from colon, 50% from cecum

Question 91

What is the cecum?

Answer 91

Inlet and outlet near the top of the large intestine | Microbial fermentation vat

Question 92

What does grain overload cause?

Answer 92

An increase in lactic acid which can cause damage to the cecal wall So much lactic acid can be produced that microbes eventually die off

Question 93

What happens in the cecum and colon for every 24 hours off feed?

Answer 93

Microbial populations drop by 50%

Question 94

How bog is the colon?

Answer 94

100-140 L

Question 95

What is the colon?

Answer 95

H2O reservoir

Question 96

What does the colon have an effect on during exercise?

Answer 96

Respiratory rate

Question 97

What does the large colon do?

Answer 97

Provides an additional location for fermentation of fibrous digesta and a site where absorption of the products of fermentation can occur

Question 98

How much water does an average horse at rest consume?

Answer 98

About 7 gallons

Question 99

What is the function of the small colon?

Answer 99

To absorb water and form fecal balls

Question 100

What does the rectum do?

Answer 100

Excrete feces