comparative anatomy of the large intestine in exotics

Question 1

what is the function of the proximal colon in rabbits

Answer 1

sperarating ingesta based on particle size

Question 2

what are the 2 types of fecal pellets in rabbits and what are their pruposes

Answer 2

• hard dry pellets = indigestible fibre that moved quickly down colon and is eliminated
• caecotrophs = small particles and fluids move retrograde back into caecum for microbial fermentation. rabbits eat this. it is soft and sticky

Question 3

discuss the track that ingesta moves through the rabbit GIT

Answer 3

Question 4

what are the major sites of GALT in the rabbit GIT

Answer 4

• sacculus rotundus (caecal tonsil) (80%)
• appendix

Question 5

what anatomical region is in the circle

Answer 5

Question 6

what is the ampulla coli

Answer 6

in between caecum and colon (‘T’ junction between end of ileum, colon and caecum.
- sorting

Question 7

what is the function of the caecum in rabbits

Answer 7

• microbial fermentation
• coiled spiral with 3 folds

Question 8

what is the function of the appendix in rabbits

Answer 8

• GALT (not as important as caecal tonsil)
• produces bicarbonate ions to buffer against VFAs

Question 9

discuss haustra and taenia in the proximal colon

Answer 9

• top has 3 haustra (sacculations) and 3 taenial bands
• distal (still proximal colon) simplifies and only has one of each

Question 10

what is warzen

Answer 10

wart like projections on inside of proximal colon to increase surface area (unique to rabbits), located on haustra

Question 11

what is fusus coli

Answer 11

• innervated musuclar section at end of proximal colon and beginning of distal colon
• goblet cells to produce lots of mucus for caecotrophs

Question 12

why are caecotrophs covered in mucus

Answer 12

• make more appealing to eat
• make stick to anus so rabbit can eat

Question 13

what species of microbes are found in a rabbit caecum and which is the predominent bacterial species

Answer 13

• balance of bacteria, protozoa, and yeast
• main species is bacteroides spp

Question 14

why do rabbits eat caecotrophs

Answer 14

full of products of fermentation (VFAs, amino acids, water soluble vitamins)
- eat it so they can access all these nutrients
- source of protein (from fermentation and bacteria themselves)
- digest ingesta twice so that they can redigest undigestible products

Question 15

discuss caecal pH

Answer 15

• pH in diurnal rhythm
• ammonia and VFAs produced by fermentation change pH
• buffered by bicarbonate ions made by appendix and dietary fibre

Question 16

when do hard fecal pellets get produced and when do soft fecal pellets get produced

Answer 16

• hard when feeding
• soft when at rest

Question 17

discuss the production of hard feces and the anatomical regions where important steps occur

Answer 17

• small particles are sorted and moved into haustra then caecum
• large particles move on
• water absorbed in proximal colon
• caecal contractility is great
• when reaches fusus coli, squeeze fecal matter to rid water
• distal colon reabsorbs water, potassium, sodium and VFAs
• dry indigestible matter expelled

Question 18

discuss caecotroph production

Answer 18

• motility changes -> caecal and proximal colon actiity decreases, distal colon activity increases (lets stuff hang arounf
• caecal material moves to large colo
• fusus coli forms pellets and adds mucus
• rapidly excreted 4 hours after feeding

Question 19

discuss the appearance of a caecotroph and give some clinical relevence why its important to know

Answer 19

• greenish outer membrane
• soft and wet
• owners may mistake as diarrhea

Question 20

discuss the contents of caecotrophs

Answer 20

• soft paste = protein, AAs, vitamins, minerals
• mucus = encapsulate pellet (made by goblet cells of fusus coli)
• lysozymes

Question 21

what is the importance of lysozymes in caecotrphs

Answer 21

• produced by distal colon
• digests bacterial cell walls
• allows rabbit to access protein inside bacteria

Question 22

what are the functions of the fusus coli

Answer 22

• pacemaker of the gut
• intitates peristaltic waves in colon
• highly innervated
• under hormonal influence
• produces mucus from goblet cells

Question 23

the presence of fibre and fat in the diet increases or decreases motility

Answer 23

increases
- fibre stimulates hindgut motility and acts as buffer for VFAs (increases caecotroph formation)
- fat increases motility and acts as energy source

Question 24

what are the consequences of protein and carbohydrates in the diet of a rabbit

Answer 24

negative effect
- less caecotrophs
- carbohydrates produce glucose which changes the bacterial balance

Question 25

what is special about hamster GIT

Answer 25

• has a pregastric pouch (high pH) for fermentation along with hundgut

Question 26

what species produce caecotrophs

Answer 26

• rabbits
• chinchillas
• small rodents (mice,, gerbils, rats, hamsters)

Question 27

discuss ferret GI

Answer 27

• strict carnivores!!
• simple stomachs
• short SI
• rapid gut transit time (important for fasting pre-op)
• no caecum or appendix
• simple GI flora