Lecture 1- Introduction to GI system of Horses Flashcards
What prevents horses from vomiting
Sharp angle of esophagus into stomach and strong esophageal muscles
What organ secretes digestive enzymes into the small intestines to breakdown food into starch, fiber, proteins and fats
Pancreas
Where is the primary site of enzymatic digestion
Stomach
How long is the small intestine
70 ft
What is broken down in the small intestine
Starch, proteins and fats
What enzyme is secreted from pancreas , enters the small intestines and breaks down starch into disaccharide
Alpha-amylase
Enzymes break disaccharides down to simple sugars which a re then
Absorbed through intestinal wall into capillary network and sent to body tissues for immediate use for energy or stored as glycogen
What is released from the pancreas in response to increased glucose levels and drives absorption of glucose
Insulin
Horses have no ____ so bile is continually secreted
Gall bladder
What is responsible for emulsifying fats and making it available for enzymatic degradation via lipases secreted from pancreas
Bile salts
Enzymatic degradation of fats via bile salts combine with vila acid to form my- cells which then….
Diffuse into intestinal lining, packaged with cholesterol and then expelled and taken up by lymphatic system via thoracic duct where lipids can be used as fuel or stored as fat
What breaks proteins to peptides in upper gut
Pepsin
Once pepsin converts proteins to peptides what happens
Amino acids are absorbed into blood capillaries and carried to tissues where they are used to build proteins
What portion of the gut is responsible for digestion of fiber
Hind gut- cecum and large intestines
What is the end product of microbial break down and fermentation
Volatile fatty acids (VFA’s)
What is the mechanism of converting glucose in hindgut
VFA—> propionate—>glucose production in liver
What happens to the proteins that aren’t absorbed in foregut and make it to hindgut
Don’t absorb amino acids—> will produce nitrogen and carbon that is excreted as ammonia
What is involved in the completion of digestion
Muscular contractions move ingesta and reabsorption of water to result in dry fecal balls
Horses are ____fermenters
Hindgut
What is the pathway from mouth to rectum
- Mouth
- Esophagus
- Stomach
- Duodenum (R)
- Jejunum
- Ileum
- Cecum (R)
- Right ventral colon
- Sternal flexors
- Left ventral colon
- Pelvic flexors
- Left dorsal colon flexors
- Diaphragmatic flexors
- Right dorsal colon
- Transverse colon
- Descending/small colon
- Rectum/anus
Where are the bands of Taenia
Large intestine
What band is located in ileum
Antimesenteric band- can’t reach on palpation
How many bands does the cecum have
4
Dorsal to ileum
Lateral to right ventral colon
Ventral/medial
How many bands does the ventral colon have
4
How many bands does the pelvic flexure have
1
How many bands does the dorsal colon have
3
How many bands does the small colon have
2
What are rugae
Series of ridges produced by folding of the wall of an organ, most commonly refers to gastric rugae of the internal surface of the stomach
What are haustra
Refer to the small segmented pouches of bowel separated by haustral folds
How are haustra formed
Circumferential contraction of the inner muscular layer of the colon
The outer longitudinal muscular layer of the colon is organized into 3 bands which run from the cecum to the rectum. What are the 3 bands called
Taeniae coli
What takes up a majority of the right side of GI tract in horse
Cecum
What takes up majority of left abdominal region of horse
Spleen
What side is the duodenum on
Right
What is the function of the stomach
Enzymatic breakdown
What is the function of the small intestines
Digests simple carbs and readily accessible proteins
What is the function of the cecum
Some carbs and proteins escape small intestine and move onto hindgut for fermentation
Where CELLULOSE (fiber) is broken down
Creates and absorbs VFA’s
What is the function of the colon
Reabsorption of water, some further fermentation
What is the function of the descending or small colon
Forms fecal balls
Where does microbial fermentation occur
Cecum and colon
Allows horses to break down cellulose (fiber)
What does fermentation in the hindgut produce
CO2, methane, VFA’s
What is propionate used for
Glucose production
What is acetate converted to and what is it used for
Converted to acetyl CoA and used for immediate energy or fat synthesis
What is butyrate converted to
Acetyl CoA
Hindgut= _____ and foregut = _____ (types of digestion)
Hindgut=Microbial fermentation
Foregut=enzymatic digestion
What are some disadvantages in horses hindgut fermentation compared to ruminants foregut fermentation
Less efficient, less nutrients entering hindgut so promotes less microbial growth, passage through hindgut is more rapid so fermentation less efficient than in rumen, protein present in microbes is not digestible thus lost
What does the microbiota consist of
Bacteria, fungi and Protozoa
what bacteria are present in microbiota
Phylum, fermicutes, bacteriodetes, proteobacteria, verrucomicrobia, actinobacteria and spirochaetes
What is the primary bacteria in the microbiota
Phylum fermicutes (46-70%)
How does the microbiota differ in a diarrheic horse vs healthy horse
Diarrheic horses have more fusobacteria and less clostridiales
Lactobaccillus is often used in ____ for horses
Probiotics
What is colic
Any abdominal pain
What are some clinical signs of colic
Sweating, pawing, tachycardia, tachypnea, up and down, rolling, stretching out, shifting, biting or looking at sides, kicking at abdomen
What divides the stomach into upper squamous and lower glandular
Margo Plicatus
what equine gastric ulcer syndrome is associated with management in horses with otherwise normal GI tracts
Primary equine squamous gastric disease
What equine gastric ulcer syndrome occurs secondary to delayed gastric emptying because of other disease states
Secondary squamous gastric disease
What is Grade=0 for ESGD
Normal
What is Grade=1 in ESGD
Hyperkeratosis
What is Grade=2 in ESGD
Small, single, or multifocal lesions
What is grade 3 ESGD
Large single or extensive superficial lesions
What is grade 4 ESGD
Extensive lesions with areas of apparent deep ulceration
What is the grading system for EGGD
No grading system, describe anatomical location, distribution and appearance
What is enteritis
Inflammatory disease of small intestine
Thickened >3mm
What are symptoms of acute:proximal enteritis
Fever, reflux, leukocytosis, colic that resolves with decompression
What are some symptoms of chronic/insidious enteritis
Inflammatory bowel syndromes, neoplasia, weight loss, panhypoproteinemia
What are some simple obstructive lesions of small intestines
Ileal impactions, adhesions and ascardiasis
What can cause ileal impactions
Feeding costal Bermuda hay (hydrophobic) and tapeworm infestation (anoplocephala)
What age group is ascardiasisa common in
4-24 months
What are some clinical signs of small intestinal strangulations
Severe pain, serosanguinous belly tap
What are some causes of small intestinal strangulations
Strangulating lipoma, epiploic foramen entrapment, intussusception, inguinal hernia
Where do strangulating lipomas form in small intestine
Stalks in mesentery
What is an epiploic foramen entrapment
Potential space: liver, caudal vena cava and portal vein
Nothing else is supposed to be there but small intestine can end up there
What is the most common intussusception
Ileocecal
What is a commonly implicated cause of intussusception
Tapeworms
What are some examples of large colon impactions
Pelvic flexure, sand impactions enteroliths, and Cecal impactions
Where is the most common large colon impaction
Pelvic flexure
Where do sand impactions accumulate
Ventral colon, rightdorsal colon, pelvic flexure
California alfalfa is associated with what large colon impaction
Enteroliths
Where are enteroliths most commonly found
Right dorsal colon/transverse colon
What large colon impaction is commonly associated with orthopedic surgical disease
Cecal impaction from stall rest and laying down a lot
What is a nephrosplenic entrapment
Left dorsal displacement
NSE of the colon hangs between the kidney and spleen
What is colitis
Inflammatory disease of large colon
What are some common etiologies of colitis
Infectious (salmonella, clostridium, coronavirus, Potomac horse fever
Verminous- encysted small strongyles
Caustic- sand colitis
What are some symptoms of colon volvulus
Severe, unrelenting abdominal pain, gross distention of abdomen
Where are colon volvulus normally located
Mesenteric attachment of the colon to the dorsal body wall involving the cecum and entire large colon
Twist at sternal/diaphragmatic flexure
What is a common impaction of the descending small colon
Fecoliths (salmonellosis)
Foals with meconioum impactions
What is peritonitis
Inflammation of peritoneum
What are some causes of peritonitis
Recent abdominal surgery, cyathostomiasis (small strongyles), IBD, internal abscess
What is the result of peritonitis
Ileus- intestines not moving can’t get gas out can result in bloat and death
Tapeworms and colic
Ileocecal intussusception, cecocolic intussusception, typhilitis
Ascarids and colic
Small intestinal impaction
Large strongyles and colic
Thromoembolic colic, cranial mesenteric aneurysm
Small strongyles and colic
Encysted cytathostomes
What does lawsonia intracellularis cause
Proliferative enteropathy
