Horse GIT Flashcards
What type of fermenter is a horse?
hindgut fermenter
what does it mean when we say a horse is a hindgut fermenter?
that the caecum and colon is evolved to provide a chamber where microbial fermentation of food takes place (also named postgastric fermentation)
what group of animals is the position of the oesophagus in a horse similar to?
similar to carnivores
what parts does a horses oesophagus consist of?
cervical, thoracic and abdominal parts
describe what happens to the lumen of a horse’s oesophagus?
the lumen narrows at the thoracic inlet and oesophageal hiatus of the diaphragm
what does the lumen narrowing result in?
it predisposes them to impaction (choke)
what is the oesophagus innervated by?
via the vagus and glossopharyngeal nerves (cranial X and IX nerves respectively)
trickle feeder?
slow chewing and produces lots of saliva
type of feeder?
horses are trickle feeders
size of a horse’s stomach?
it is relatively small (5-15ft capacity)
how long does a horse graze for in a day?
17 hours
where does the stomach lie in a horse?
the cranial part of the abdominal cavity, mostly to the left of the median plane
ball size reference of the stomach?
baseball
type of stomach?
horses stomachs are simple stomachs like pigs, carnivores and rabbits
cardia?
entrance of the stomach
how many ribs do horses have?
18
where is the cardia located?
it has a relatively fixed point - opposite the upper part of the 11th rib
how many sections is the small intestine of the horse divided into and what are they?
3 - the duodenum, jejunum and ileum
what side is the descending duodenum always on?
the right side
location of the descending duodenum?
DORSAL on the right side of abdomen, suspended form the dorsal body wall by the mesentery (medoduodenum)
location of the jejunum?
to the left dorsal part of the abdomen
what is the jejunum associated with?
with a long mesentery
the jejunum is very…
mobile
what restricts the jejunum to the position that it is in??
the large caecum on the right and the ascending colon ventrally on both sides of the body
which part of the small intestine joins to the large caecum?
the ileum
what is the name of the fold from ileum to caecum?
it is called the ileocecal fold
what issues does the length of the mesentery cause?
loops of small intestine can becomes twisted or trapped in natural openings
describe where the ileum enters the caecum:
on the medial side at the junction of the organs base and body - if you look at the horse from the right hand side you won’t be able to see its entrance
ileocaecal fold?
is connecting peritoneum
what are the three parts of the large intestine?
the caecum, ascending and descending colon
what are bands and sacculations?
they are characteristics of the large intestine of horse, pig and human NOT found in carnivores and ruminants
what does the colon consist of?
the large ascending colon, the transverse colon and the descending colon
which is the most modified part of the colon of a horse?
the ascending colon
describe how the ascending colon is arranged:
it is arranged into two U shaped loops laying on top of each other
where is the caecum?
it is on the right hand side so the first colon will be right ventral colon or connected to the caecum via cecocolic orifice
what is the first flexure of the large intestine? and then what other flexures?
the sternal flexure, then the left ventral colon, then pelvic flexure, then left dorsal colon diaphragmatic flexure
taenia?
longitudinal bands
sacculations/haustra?
transverse infolding of the intestinal wall to from serial sacs
what are the three parts of the large intestine characterised by?
sacculations and taenia
where does the liver lie?
within intrathoracic part of the abdomen and extends from 6th intracostal space crinioventrally to 15th intracostal space caudodorsally on the right
what is the liver covered in?
in visceral peritoneum
why does the horse’s right liver lobe atrophy (for most horses)?
it is as a result of constant pressure from the Right Dorsal Colon
FOR THE DIAPHRAGMATIC SURFACE OF LIVER
lobes in order of appearance of the liver:
right lobe, quadrate lobe, left medial lobe and then left lateral lobe
FOR VISCERAL SURFACE OF LIVER
what are lobes in order of appearance:
left lateral lobe
left medial lobe
quadrate lobe
right lobe
caudate lobe
shape of pancreas?
roughly triangular
location of pancreas?
its body is cranial and lies cranial part of the duodenum
where does the left lobe of the pancreas extend across to?
extends across the median plane to the left where it makes contact with stomach
location of right lobe of pancreas?
it follows the descending duodenium and related to the base of the caecum
where does the bile and pancreatic duct of a horse open?
at the first bend of the duodenal sigmoid flexure (duodenum makes this S shape turn)
pancreatic ducts of a horse?
both the pancreatic and accessory ducts
teniae?
number of longitudinal smooth muscle cords on the caecum and colon
teniae used to distinguish?
distinguish between parts of the large intestine and small intestine
how many bands of teniae on caecum and ventral colon incl. sternal flexure?
4
how many bands of teniae on right dorsal colon?
3
how many bands of teniae on descending colon of large intestine?
2
how many bands of teniae on left dorsal colon and pelvic flexure?
one
how many bands of teniae on small intestine?
none
what do the teniae result in the formation of?
hastra/sacculations which are a series of pouches in the walls of the caecum and colon - formed by these teniae
where can we see the blind sac?
fundic part of stomach
how/where does the oesophagus enter the stomach?
obliquely
sphincters?
pyloric and cardiac sphincters
why do horses find vomiting hard?
due to pyloric and cardiac sphincters
structure of ileum when palpated?
much tougher structure
where does the ileum join the caecum?
on the left hand side
the medial part of the caecum
what parts of the caecum are there?
the body, the apex and the base
where is the base of the caecum situated?
situated at the right paralumbar fossa
where does the right ventral colon turn?
at the sternal flexure
left ventral colon travels towards…
pelvic inlet
pelvic flexure?
left ventral colon turning back on itself - then becomes left dorsal colon
when the left dorsal colon folds? - then becomes the right dorsal colon (very short part of the intestine)
diphragmatic flexure
what does the right dorsal colon then join?
the transverse colon
what follows the transverse colon?
the descending colon
how many metres is the descending colon in horses?
2-4m
teniae are innervated by?
nerve fibres
right dorsal colon situated?
inside the ribcage
small intestines do not have…
tenaie (taeniae)
which section of the small intestine has a long mesentery allowing for great range of motion?
the jejunum
ascending colon of large intestine?
It is about 4metre long and hold avarage of 80lt.It is folded to form double loop (A bit like a double horse shoe)
which liver lobe is missing in the horse?
papillary process
Caudate lobe is lacking papillary process in the horse but still has caudate process
list the parts of the ascending colon in correct order:
Ascending colon
RVC
sternal flexure
LVC
pelvic flexure
LDC
diaphragmatic flexure
RDC
shape of the caecum in a horse and the parts of the caecum in the horse?
it is COMMA shaped and consists of the base, body and apex
Which two parts of the oesophagus predisposes them to choke in the horse?
Oesophagus has three parts just like other species cervical, thoracic and abdominal. Its lumen narrows at the thoracic inlet and oesophageal hiatus of the diaphragm; this predisposes them to impaction (choke)
What does the term choke refer to?
*The term “choke” actually refers to an obstruction of the oesophagus, as opposed to an obstruction of the trachea when a human chokes.
On which side of the horse’s neck can the oesophagus be palpated?
the left
What risk factors do you think might predispose horses to developing oesophageal obstruction?
Poor dentition, bolting their food, and eating improperly soaked feed are some of the more common risk factors for choke.
What is EGUS?
Equine gastric ulceration syndrome
It is a common syndrome in all horse populations, but is especially prevalent in the racehorse population, with up to 100% of horses in race training affected in some studies.
EGUS is an all encompassing term for all ulcerative or erosive diseases of the stomach. What is EGUS further broken down into?
ESGD - equine squamous gastric disease
EGGD - equine glandular gastric disease
what common equine intestinal parasite attaches at the ileocaecal junction?
tapeworm
right ventral colon?
The is the first section of the ascending colon, and connects to the caecum at the caecocolic orifice.
Some people remember this with “RVC comes first”…
Which flexure lies between the left ventral colon and the left dorsal colon?
pelvic flexure
