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What is an abnormal result of the NMB reduction test?
takes longer than 5 min for color to return to that of normal rumen fluid (microbes not functioning/not there)
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What are tests to assess rumen function? (6)
auscultation (2-3 ruminations per 2 min), visualize protozoa, NMB reduction test, smell, pH (should be alkaline), chloride (inc. Cl- in rumen and low systemic Cl- indicates decreased pyloric outflow)
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The omasum lives in the __________ abdomen and functions to...
right cranial; absorb water, electrolytes, VFAs.
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The __________ of a neonatal ruminant is the biggest compartment of the GI, but when they are weaned and begin to eat forages and grains, the ___________ becomes the biggest compartment.
abomasum; rumen
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In the neonate, the ___________ is essential to prevent milk from entering the rumen.
rumenoreticular groove (aka- esophageal groove, gastric groove)
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The glandular mucosa of the abomasum secretes... (3)
HCl (fundus), pepsinogen (pylorus), and mucus (pylorus)
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The ruminant upper GI is suppled blood by the ___________; it is drained by the ___________.
celiac artery; portal system
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What are the innervations of the ruminant upper GI?
- vagus nerve dorsal trunk- rumen
- vagus nerve ventral trunk- omasum, abomasum, reticulum
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Within the rumen, the host provides __(3)__ and the microbes provide __(3)__.
nutrients, warmth, and a buffered environment; B vitamins, VFAs, and microbial proteins
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What types of rumen bacteria are there? (6)
cellulose/pectin degraders (degrade plant cell walls), starch degraders (amylolytics), protein degraders (proteolytics), lipid degraders (lipolytics), lactate users, methanogens
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What is the function of methanogens in the rumen?
regulate overall fermentation by removal of hydrogen
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What is the function of rumen protozoa?
ingest bacteria for intraluminal nitrogen recycling
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What are the functions of ruminal fungi? (3)
degrade cellulose and xylans, contribute to fiber degradation, facilitate bacterial colonization
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What is the gradation of rumen contents in ruminants?
[on top] gas cap, fiber mat (today's hay), heavy particles (grain and yesterday's hay) [on bottom]
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What kind of bacteria live in the rumen and why?
only anaerobes because oxygen is only 0.5% of the gas in the rumen gas cap
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What are advantages of pre-gastric fermentation? (3)
energy from fibrous materials (VFAs), microbes are an amino acid source, production of B vitamins
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What are the disadvantages of pre-gastric fermentation? (3)
inefficient use of nutrients (starches, sugars, proteins) compared to intestinal digestion, value of high-quality proteins decreased, fermentation can get out of control
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Primary rumen contractions are responsible for ___________; secondary contractions are responsible for ______________.
mixes contents; eructation of fermentation gases
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_______ provide 80% of the animal's energy needs; they are produced in the __________ and absorbed through the ___________.
VFAs; rumen; rumen wall
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What are the major VFAs produced in the rumen? (3)
acetate, proprionate, butyrate
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__(2)__ move to the abomasum and are broken down as ___________ for host.
Microbes and undigested material; protein source
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Ruminal tympany results from ___________, not __________.
failure of eructation; overproduction of gas
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Potential causes of rumen tympany. (3)
esophageal obstruction, rumen motility disorders, fluid/foam at cardia (frothy bloat, recumbancy)
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What causes free gas bloat? (2) How can you identify it?
physical obstruction prevents gas from eructation, rumen hypomotility; passage of tube relieves bloat
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What causes frothy bloat? How can you identify it?
thick foam from grain overload/lush legumes; tube does not relieve bloat (foam doesn't pass through tube)
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Hw can bloat result in death?
rumen fills and pushes on diaphragm--> inhibition of respiration--> dyspnea--> death
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What are signs of choke? (3) What is a sequelae of choke?
dysphagia, drooling, (late change) acidosis; free gas bloat (cannot eructate)
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____________ is the hallmark of ruminal motility disorders, leading to... (5)
Vagal indigestion; interference with vagal innervation of rumen, hypomotile rumen, frothy/free gas bloat, disruption of normal rumen flora, failure to clear cardia before eructation
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Describe the pathogenesis of frothy bloat.
lush legumes/high conc diets--> rapid digestibility--> microbial proliferation--> multiplying bacteria release mucopolysaccharide--> slime/biofilm and stable foam
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How do you treat free gas bloat? (4)
esophageal intubation/lavage, FB retrieval (if needed), rumenotomy, [emergency] rumen trocar for decompression
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How do you treat frothy bloat? (2)
Poloxalene (TheraBloat), +/- rumenotomy
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Why is rumen trocar for emergency decompression of bloat ONLY for emergency use (respiratory distress)?
peritonitis will result
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When is a rumenostomy indicated?
relief of chronic bloat
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What are the classifications of vagal indigestion? (4)
failure of eructation (free gas bloat), omasal transport failure (anterior functional stenosis- most common type), pyloric outflow obstruction (posterior functional stenosis), indigestion of late pregnancy
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What parts of the GI are distended with omasal transport failure?
rumen distention WITHOUT absomasal distention [PAPPLE]
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What parts of the GI are distended with pyloric outflow failure?
abomasal distension, omasal distention, rumen distention
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Causes of vagal indigestion. (6)
traumatic reticuloperitonitis [hardware], reticular abscess [hardware], liver abscess, pneumonia, abomasal volvulus, abomasal ulcers [all things that interfere with the vagus nerve]
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What are clinical signs of vagal indigestion? (5)
Papple abdominal distension, how HR, hypermotile/weak rumen, scant feces, undigested feedstuff in manure
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Grain overload causes ____________.
rumen acidosis/lactic acidosis
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What are highly fermentable feeds? (3)
cereal grains, root crops (beets/potatoes), fruit
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Describe the pathophysiology of grain overload/rumen acidosis.
excessive carb ingestion--> increased bacterial growth and VFA production--> lower pH--> Strep bovis flourishes (lactate producer)--> increased lactic acid--> lactic acid users start dying off due to low pH--> pH further decreases--> Strep bovis dies (due to low pH) and lactobacillus flourishes (lactic acid producer)--> more lactic acid production--> further drop in rumen pH--> increased osmolality--> increased thirst, rumen distention, hypovolemia, rumenitis
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What are direct consequences of the pathophysiology of excessive carb ingestion? (9)
increased rumen osmolality leading to increased thirst, rumen distention (filling with fluid), hypovolemia, rumenitis; increased VFAs leads to lactate and ketones released into systemic circulation, decreased rumen motility, systemic acidosis
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What form of lactic acid accumulates in the rumen wall?
D-lactate (produced by microbes) (b/c animals produce L-lactate, therefore they are better at clearing it)
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Where is lactate metabolized in the body? What is a by-product of its metabolism?
liver; bicarbonate
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What are systemic effects of rumen acidosis and damage to rumen epithelium? (3)
endotoxemia, laminitis, liver abscesses/caval syndrome
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How does caval syndrome secondary to grain overload present? (3)
bleeding from nose, [on necropsy] liver abscesses, caudal vena cava thrombi
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What are clinical signs of grain overload? (6)
depression, abdominal distention, tachycardia, diarrhea, death, laminitis
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How do you treat grain overload? (5)
rumen evacuation (kingman tube or rumenotomy), transfaunation (put healthy rumen fluid in), systemic antibiotics (rumenitits/liver abscesses), antifungals (mycotic rumenitis), IV fluids (hypovolemia)
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What are the 3 types of hardware disease?
traumatic reticulitis (usually asymptomatic), traumatic reticuloperitonitis (most common presentation), traumatic reticulopericarditis (most serious)
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How do you treat hardware disease? (4)
antibiotics (peritonitis), magnet, +/- rumenotomy to remove FB/drain abscess, +/- pericardiocentesis/ 5th rib resection/ pericardectomy
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What are predisposing factors to DAs? (7)
GI (abomasal) atony due to a change in diet, high conc diet, concurrent diseases (esp. ketosis); recent calving leads to increased metabolic demands and a void in the abdomen
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Clinical signs of simple DA? (5)
decreased milk, decreased appetite, depression, ketosis, ping
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What are clinical signs of a abomasal volvulus? (9)
down on milk, decreased appetite, depression, ketosis, ping, colic, tachycardia, shock, death
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What metabolic derangements are usually associated with DAs? (4)
hypochloremic, hypokalemic, metabolic alkalosis, [late dz-volvulus] lactic acidosis
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