Livestock Diseases of Rumen

Question 1

basic rumen anatomy

Answer 1

• rumen occupies Left side of abdomen
• most cranial aspect is reticulum (immediately behind diaphragm)
• lying along rumen is spleen

Question 2

what is the cardia

Answer 2

orifice of esophagus leading into the rumen

Question 3

what is the esophageal groove

Answer 3

leads to reticuloomasal orifice- defines the border of the reticulum and the chambers of the rumen

Question 4

chambers of the rumen

Answer 4

atrium, dorsal sac and ventral sac

Question 5

T/F: the omasum is very rarely impacted by disease

Answer 5

true

Question 6

what is the HCl secreting chamber of the forestomach

Answer 6

abomasum

Question 7

rumen fermentation

Answer 7

• carbohydrates: sugars, structural CHO
• proteins: manufactured by microbes, some bypass rumen
• bacteria/protozoa/yeast break down feedstuffs
• ruminoreticulum: fermentation vat where cellulose gets digested to usable energy

Question 8

volatile fatty acids (3 types)

Answer 8

1. acetate: 2 carbon, lipogenic
2. propionate: 3 carbon, glucoggenic
3. butyrate: 4 carbon, ketogenic
   these are similar to CHOs but acids because the have a hydroxyl part
   utilized by liver to make glucose or enter TCA and generate ATP

Question 9

what parts of the forestomach are non-glandular mucosa?

Answer 9

rumen, reticulum, omasum: absorptive epithelium
primary purpose of absorbing VFAs produced by fermentation

Question 10

what parts of the forestomach are glandular

Answer 10

abomasum: very similar to monogastric and digest similar

Question 11

what is the motor function of the rumen?

Answer 11

1. primary contractions: most important for fermentation
2. secondary contractions: eructating gas
3. eructation itself
4. regurgitation: small contraction but provides regurg material to be re-masticated
5. esophageal groove: operative in neonates: closes for milk to go to abomasum
6. control mechanisms: when these are abnormal = see disease

all of these happen in coordinated fashion

Question 12

what are the components of fermentation of the rumen?

Answer 12

1. inflow: feedstuffs, saliva: important to buffer contents
2. outflow: absorption of liquids like VFAs, water, electrolytes, passage of ingesta aborad
3. fiber fermentation
4. concentrates: mainly starch and are fermented rapidly (ex cereal grains)

Question 13

what things do primary contractions do?

Answer 13

1. mix ingesta: maceration of fibrous feeds
2. stratifies rumen contents bc of cyclic nature: lighter things float to top and dense particles set at bottom
3. sort feed by particle size: selective passage of small particles to omasum
4. aborad movement of material that has been well fermented
5. enhance VFA absorption: needs contact of VFA with rumen epithelial cells: mixing makes them come in contact with rumen wall
6. enhance contact of feedstuffs with bacteria: liquid cycling ontop of fibrous material and trickles back down

Question 14

what stimulates primary contractions?

Answer 14

• all controlled by vagal nerve regulation
• feeding/chewing
• low threshold receptors that signal rumen distension
• abomasal acidity: needs more ingesta passed
• environmental cold: rumen generates heat without utilizing other thermoregulatory pathways

Question 15

what inhibits rumen primary contractions?

Answer 15

• high VFA concentrations: too much acidity too fast fermentation
• high threshold receptors: rumen wall too tight (can be mimicked if rumen grossly distended
• pain
• CNS depression and systemic illness/fever

Question 16

what is the end effect of the coordinated rumen contraction?

Answer 16

stratification of rumen contents: light material floats to top, fluids flow up with contraction and trickle down
small particles drop towards bottom: cycle into atrium, reticulum, then go to reticulo-omasal orifice

can palpate the fiber mat, fluid feel in ventral aspect and gas cap up top

Question 17

what do secondary contractions do?

Answer 17

1. move gas to cardia
2. primary function is to prepare gas for eructation
3. dorsal sac contracts to push gas towards cardia
4. ingesta drops below cardia and then clears cardia and prepares for eructation

Question 18

eructation is a complex movement- describe its mechanisms

Answer 18

• requires relaxation of esophagus
• requires CLOSURE of glottis and inhale slightly
  ^ this creates negative pressure to pull gas into the esophagus and have it flow out thru the oral cavity = negative thoracic pressure to increase rate of gas flow into esophagus

Question 19

how does regurgitation occur?

Answer 19

• similar to eructation
• contraction of rumen is a reticular contraction that lifts feed up to cardia
• when feed presented to cardia, animal has a similar movement as eructation except: when this occurs, is pulling a volume of fibrous feed material up to the oral cavity to be re-masticated

Question 20

how does the rumen buffer VFAs?

Answer 20

• rumen lining coated with villi: shag carpet
• villi buffer rumen by absorbing VFAs and having electrolyte exchange
• ruminants produce bicarb by salivary glands! contained within saliva
• this is eructated every time the animal is chewing, eating swallowing
• bicarb rich saliva gets to rumen to help buffer acidic nature

Question 21

what happens if a cow cannot clear the cardia?

Answer 21

cannot eructate, can’t ruminate and chew cud

Question 22

what happens if there are excessive VFAs produced?

Answer 22

rumen acidosis, shutdown/rumen atony

Question 23

what happens if an animal is fed forage with no readily fermentable carbohydrate?

Answer 23

creates a whole nother issue- hay belly!

Question 24

what happens if there is an obstruction of the reticulo-omasal orifice? (where foreign bodies will obstruct, esp goats and sheep)

Answer 24

obstructive indigestion

Question 25

how do you examine the rumen in a PE?

Answer 25

- observe from distance: animal stance, abdominal contours, distension - auscultation - ballottement: take fist and depress into abdomen to assess what you can feel: determining the consistency of abdominal contents - percussion: evaluate fluid-air interfaces - rectal exam

Question 26

how might a cow display abdominal pain?

Answer 26

- arched back - tucked up abdomen - abducted elbow - reluctant to move

Question 27

what is visceral pain?

Answer 27

distension, stretching ischemia: results in "colic": kicking, looking at abdomen, lying down, or getting up and down

Question 28

what is parietal pain?

Answer 28

caused by inflammation of the serosal surfaces: leads to abnormal posturing, grunting, reluctance to move

Question 29

what is seen more commonly in cattle, visceral or parietal pain?

Answer 29

parietal pain: have more issues with peritonitis/pleuritis than typical SI distension disease

Question 30

what causes a "pear" shape in a cow?

Answer 30

- this is bilateral ventral abdominal distension - pregnancy, hydrops, urinary bladder rupture, increased free peritoneal fluid, heavy, distended multiple loops of SI

Question 31

what causes a "papple" shape in a cow?

Answer 31

- classic vagal indigestion look - dorsal distension on one side, ventral distension on other side - rumen problem!

Question 32

what causes an "apple" shape in a cow?

Answer 32

- classic rumen distension, distension in dorsal aspect bilaterally

Question 33

what are the 5 F's of abdominal distension?

Answer 33

fluid, feces/food, fetus, fat, flatus (gas)

Question 34

common causes of uniform abdominal distension

Answer 34

1. increased free abdominal fluid 2. diffuse distension of SI

Question 35

you see a cow that has distension in the lower right quadrant. what is your differential?

Answer 35

think anatomy- abomasum is there! could be displacement/R volvulus

Question 36

if you hear tinkling when the rumen moves, what does this indicate?

Answer 36

that there is reduced/no fiber mat in the rumen

Question 36

what are normal rumenal sounds on auscultation?

Answer 36

- thundering/rumbling sound from fiber mat moving with rumen contracitons - the contractions result in vibrations and you hear those vibrations - the sound related to fiber mat is a very deep tone

Question 37

what are the layers within the rumen?

Answer 37

1. free gas up dorsally 2. fiber mat (course roughage) (doughy compressible layer) 3. fluid layer ventrally

Question 38

how does a ping get generated?

Answer 38

percussing external part of abdomen, setting a vibration, which reverbs back with high pitched tone resonance comes from the vibration of gas over a smooth surface

Question 39

if the surface over which the gas is moving over is not smooth, what sounds will you hear?

Answer 39

will sound like a dull thud if smooth, comes back as a very high pitched type of vibration

Question 40

what are the requirements to hear a ping?

Answer 40

1. gas/fluid interface 2. viscous under pressure 3. viscous adjacent to abdominal wall 4. gas distended viscous must be against body wal 5. both pinging and stethoscope must be over gas distended viscous

Question 41

in a normal animal, what should you hear when percussing an animal?

Answer 41

nothing- should sound like a "thud"

Question 42

in an animal with viscous gas distension, what will you hear?

Answer 42

"ping" resonant "tinking"

Question 43

if you hear a ping on the left side of a cow, what is on your differential list

Answer 43

1. pneumorectum 2. LDA 3. empty rumen 4. gas distended rumen/rumen bloat 5. physometra 6. pneumoperitoneum

Question 44

if you have an LDA, where should you "ping"?

Answer 44

cranial to the 10th rib and positive succussion

Question 45

if you hear a right sided ping, what is on your differential list?

Answer 45

1. RDA 2. abomasum volvulus 3. cecal dilation 4. cecal volvulus 5. ascending colon gas 6. penumoperitoneum 7. pneumorectum

Question 45

when collecting rumen fluid, what parameters are you evaluating?

Answer 45

1. color: normally green-brown 2. odor: less aromatic odor with less fermentation 3. consistency: tends to be slightly viscous, will have gas bubbles within 4. pH: wide range , influenced by diet 5. chloride level: normal is <25mEq/L: submit to lab 6. methylene blue reduction: measure of activity of microflora (anaerobes) 7. sedimentation/flotation: also microflora 8. wet mount/prep: look at protozoa