Exam 3 - Forestomach Disorders Flashcards
how is rumen health assessed by rumen fluid analysis?
protozoal numbers & activity
new methylene blue reduction
sedimentation examination
what is the new methylene blue reduction test? what is an abnormal result?
qualitative measure of the redox potential of rumen fluid generated by microbial fermentation to check for the function of anaerobic bacteria
abnormal - > 8-10 minutes, indicates microbial inactivity/death
what is a sedimentation rate used for rumen fluid analysis? what is an abnormal result?
qualitative estimate of microbial activity & dietary particle size
floatation is minimal or not observed with inactive/decreased particle-associated bacteria - can indicate frothy bloat
what is simple indigestion/rumen dysbiosis?
transient inappetence due to changes in rumenal microenvironment
what are some general causes of simple indigestion/rumen dysbiosis?
moldy/spoiled feed, indigestible roughage, too much feed, & new type/batch of feed
how is simple indigestion/rumen dysbiosis diagnosed?
rule out - usually multiple animals are affected
what are the clinical signs associated with rumen dysbiosis/simple indigestion?
decreased appetite, decreased milk production, rumen hypomotility, mild bloat, & abnormal feces
how is simple indigestion/rumen dysbiosis treated?
usually resolves spontaneously once the feeding error has been corrected
what causes rumen acidosis?
overindulgence on carbs
readily digestible carbohydrates (such as starch. sugar, or pectin) are rapidly fermented an unadapted rumen resulting in increased VFA & lactate concentrations & a reduction in rumen pH
what are some common offenders that cause rumen acidosis?
cereal grains - corn, wheat, barley
high sugar/starch fruit or root crops
corn or milo stubble fields
byproduct feeds - bakery waste & brewer’s grain
what is the pathogenesis of rumen acidosis?
- within 2-6 hours after ingestion, rumenal bacterial population begins to shift towards increased numbers of gram positive bacteria
- fermentation is altered with a shift in VFA production from acetic > propionic > butyric to propionic > acetic > butyric and increased concentrations of undissociated VFAs lactate & glucose
- rumen protozoa decline & lactate begins to accumulate at pH of 5.5 - dying protozoa release amylase & contribute to increased glucose generation from starch
- these conditions favor proliferation of strep bovis & other gram positives that produce lactate & once pH falls to 5.0, gram negative organisms decline rapidly & there is a local release of endotoxin
- pH 4.5, lactobacillus spp. predominate with rapid production of lactate & histamine
- ability of the rumen to buffer acid is overwhelmed at pH <5, and D- & L- lactate accumulate causing a systemic lactic acidosis & metabolic acidosis
- rumen epithelium is damaged as a result of acids & other mediators released during acute acidosis
what bacteria predominate during rumen acidosis?
step. bovis & lactobacillus
what is going on with d-lactate & l-lactate during rumen acidosis?
l-lactate is metabolized but d-lactate isn’t & it builds up causing a metabolic acidosis
what damage occurs to the rumen epithelium in rumen acidosis?
chemical rumenitis, epithelial necrosis, absorption of bacteria into portal blood, & bacterial & fungal rumenitis
T/F: acute rumen acidosis is an individual animal disease while subacute rumen acidosis is a herd disease
true
what are some clinical signs associated with acute rumen acidosis?
individual animal disease!!!! sick!!!!
anorexia, depression, splashy/distended/static rumen, dehydration, tachycardia, cold extremities, weak or recumbent, diarrhea with or without grain, & death
what factors can influence the development of acute rumen acidosis?
rate of dietary adaption, type of carb & processing method, forage availability, feed sorting, feeding frequency, feed intake, & feed mixing/delivery
why are clinical signs of subacute rumen acidosis not as severe as acute?
the changes in fermentation rate, pattern, & rumen pH are temporary & not as severe
what is supportive of acute rumen acidosis on rumen fluid analysis?
foul smell, pH <5.5, & dead protozoa & gram positive bacteria
what may be seen on lab tests in an animal with acute rumen acidosis?
metabolic acidosis, increased anion gap, hemoconcentration, pre-renal azotemia, & mild-to-moderate hypocalcemia
what are some clinical signs associated with subacute rumen acidosis?
herd disease!!!
decreased/variable feed intake, decreased performance/increased culling, increased incidence of lameness, milk component changes (decreased milk fat % & inversion of fat:protein ratio), & loose feces
T/F: history & physical exam findings will not be pathognomic for subacute rumen acidosis
true
how can subacute rumen acidosis be diagnosed?
ration analysis, rumenocentesis (pH >5.8, normal), manure scoring, lameness scoring, & milk fat inversion
why does sudden introduction of fermentable carbs or a sudden change in amount of fermentable carbs carry a higher risk of developing acute rumen acidosis?
dietary adaption is necessary to build up populations of lactate-using bacteria, and you need to maintain the equilibrium between acid production & acid utilization
what is the classic example of acute rumen acidosis?
animals accidentally gain access to a grain storage area & engorge themselves
why does processing method carry risk for an animal developing rumen acidosis?
small particle size (fine grinding), heat or pressure processing, & high moisture storage of grain increase starch availability
list the types of carbs that carry the highest risk of rumen acidosis
wheat = barley > corn > sorghum = oats
how can feeding smaller meals frequently help prevent rumen acidosis?
not as much grain in the food when compared to 1 large meal
what are some examples of causes for fluctuations in feed intake?
inclement weather, disease, management changes
what animals may show predisposition to developing acute rumen acidosis?
feedlot animals/dairy cattle in transition from the dry to lactating period
dairy cattle in early lactation
animals being fitted for show or sale
T/F: acute rumen acidosis is one of the rare conditions that results in metabolic acidosis in adult ruminants
true
what are the principles for treating rumen acidosis?
remove further access to carbs - evacuate rumen contents (surgical or rumen lavage), correct dehydration & systemic acidosis, neutralize rumen pH
stop acidification, correct metabolic abnormalities, reestablish flora, prevent sequelae, surgical/medical intervention
what are some possible sequelae of rumen acidosis?
bacterial rumenitis, bacteremia/septicemia, fungal rumenitis, liver abscesses, metastatic pneumonia, polioencephalomalacia, & laminitis
how is rumen acidosis prevented?
prevent accidents, transition cattle slowly to high concentrate diets, use ionophores, & buffers
how is subacute rumen acidosis treated?
managed by dietary changes rather than treatment of individual animals
what is bloat?
occurs when eructation is impaired & the rumen becomes overdistended with froth or gas
what is primary ruminal tympany?
dietary factors lead to frothy or foamy rumen contents - gas bubbles are trapped by the froth/foam & eructation of gas is prevented
what is secondary ruminal tympany?
following physical obstruction of the cardia or impairment of the rumenoreticular function with accumulation of free gas in the rumen
what is the similar appearance & clinical signs shared between animals with primary & secondary ruminal tympany?
distended rumen & left paralumbar fossa
dyspnea, abdominal pain, staggering, & death
how does a stomach tube help differentiate between primary & secondary ruminal tympany?
primary - stomach tube passes easily but does not relieve bloat, frothy contents may be seen at the end of the tube
secondary - stomach tube passes & relieves bloat or the stomach tube will not pass
primary ruminal tympany affects what animals?
ruminants on pasture - pasture bloat
ruminants fed high concentrate diets - feed lot bloat
when can frothy bloat affect feedlot cattle?
those fed high protein pelleted rations early in the feeding period
what is the pathogenesis of pasture bloat?
foaming agents (soluble proteins) are contained in the plant - lush, rapidly growing legumes (alfalfa, clover, winter wheat) that contain large amounts of proteins that are rapidly degradable & produce gas at a rapid rate - gas is trapped in the froth/foam
what is the pathogenesis of feedlot bloat?
high grain diets slow rumen motility & decrease saliva production
ingestion of high grain, low roughage (> 50% grain) diets results in mucopolysaccharide (slime) production by bacteria within the rumen which increases the viscosity of rumen fluid resulting in trapped gas & formation of stable foam
why do finely ground diets increase the risk of feedlot bloat?
they increase the fermentation rate & decrease salivation
when is feedlot bloat most likely to occur?
transition to a high grain diet is rapid or when very high concentrate diets are fed for a long time late in the finishing period
what are some clinical signs of primary ruminal tympany?
severe abdominal distension, gasping for breath, prolapsed rectum, raised tailhead, & dead
what is the preferred treatment for pasture bloat?
poloxalene - ionic surfactant that lowers the surface tension of foam
what is the preferred treatment for feedlot bloat?
intraruminal administration of mineral oil to destabilize froth
with both pasture bloat & feedlot bloat, why tie a rag in the animals mouth?
helps increase saliva production & stimulates chewing which increase rumenoreticular motility
how is primary rumen tympany prevented?
antifoaming agents, grazing control - rotational or strip grazing, limit overgrazing, graze mature pasture, mixed pastures, feed prior to turnout
feed ionophores
what is secondary rumen tympany?
occurs when gas production continues but eructation of gas is limited - failure of eructation
what are some examples of causes of secondary rumen tympany?
esophageal blockage & during step up to a high concentration diet
how is secondary rumen tympany diagnosed?
pass a tube - try to release gas & treat the underlying cause
how is secondary rumen tympany treated?
cause dependent - if you can’t pass a tube, can do an indwelling rumen trochar or temporary rumenostomy
when is rumen fluid analysis indicated?
off-feed animal
rumen atony
abdominal or rumen distension of undetermined origin
history consistent with indigestion, acidosis, or urea toxicosis
assist in diagnosis of feed quality or feed mixing/delivery problems
