Lecture 21 3/25/25 Flashcards
What is the normal rate of rumen contractions?
2 contractions a minute to 3 contractions every 2 minutes
What are the typical layers found within the rumen/
-gas at the top
-fiber mat in the middle
-fluid phase at the bottom
What is the purpose of primary rumen contractions?
move material from the rumen to the reticulum
What is the purpose of secondary rumen contractions?
eructation of gas out of the rumen
What are the main volatile fatty acids?
-acetate
-propionate
-butyrate
Which molecules are fermented by bacteria in the rumen?
-glucose
-fat
-microbial proteins
-essential vitamins
What is the role of acetate?
building block for fatty acids such as butter fat and triglycerides
What is the role of propionate?
glucose precursor that provides resources for the Kreb’s cycle
What is the role of butyrate?
less commonly utilized, more inert byproduct of fermentation
What causes each of the abdominal contours in the depiction?
A: rumen tympany/free gas bloat
B: frothy bloat
C: vagus indigestion
D: right-sided distention due to cecal volvulus or RTA
E: abomasal impaction
How can rumen fluid be collected?
-OG tube: will be contaminated with saliva
-rumenocentesis: requires percutaneous aspiration
What is the pH of normal rumen fluid, acidotic rumen fluid, and saliva?
-normal rumen: 5.5 to 7 pH
-acidotic rumen: < 5.5 pH
-saliva: 8 pH
What is the typical cause of high rumen fluid pH?
salivary contamination
What is the normal odor of rumen fluid?
aromatic and unobjectionable
What is the qualitative examination of rumen fluid?
-observation of big, medium, and small protozoan activity
-want a good amount of activity from all three sizes
-larger protozoa will die off first when problems occur
Which metabolic function test can be done on rumen fluid?
new methylene blue reduction
What are the characteristics of simple indigestion?
-mild disruption of normal rumen fermentation
-occurs with sudden diet changes, stress, and spoiled feed
What are the clinical signs of simple indigestion?
-mild bloat
-diarrhea 12 to 24 hours later
-decreased milk production
-weak rumen contractions
What are the treatment steps for simple indigestion?
-typically self-resolves
-free choice bicarbonate
-transfaunation
-good quality hay
-possibly probiotics
What are the characteristics of ruminal acidosis?
-dramatic disruption of rumen fermentation
-abrupt change in the non-structural carbohydrates
-exacerbated by external stressors
How does the level of feed processing impact digestibility and bloat?
feeds that are more highly processed and/or have more moisture are more digestible/fermentable; more gas is produced which increases chances for bloat
What are the steps of rumen acidosis pathogenesis?
- excessive grain/starch intake
- non-structural carbs are converted to glucose
- glucose is used to produce VFAs and D- and L-lactic acid
- D- and L-lactic acid destroy good microflora and epithelium, reduce motility, and are systemically absorbed
- destroyed microflora release endotoxins
- Fusobacterium necrophorum, Trueperella pyogenes, and Strep. bovis cause rumenitis and enter circulation
- lactic acid production and abnormal fermentation dramatically increases rumen fluid osmolality; water rushes into rumen and causes distention
How does L-lactic acid differ from D-lactic acid?
-L-lactic acid results from anaerobic metabolism and is normal
-D-lactic acid is produced by bacterial fermentation and cannot be used by mammals
What are the clinical signs of acute ruminal acidosis?
-toxemia
-bloat
-dehydration
-ataxia
-recumbency
-metabolic acidosis
-fetid diarrhea
-possible death
What are the clinical signs of subacute ruminal acidosis/SARA?
-signs similar to recurring simple indigestion
-incidence increased with stress
What are the clinical signs of chronic ruminal acidosis?
-months of ups and downs in fermentation
-thickening and cornification of rumen wall
-blunting of papillae
-poor production
-unthrifty
Why is acute ruminal acidosis life threatening?
-abdominal pressure can impact CV system
-acidemia can cause death
How is ruminal acidosis diagnosed?
*clinical presentation and history
*rumen fluid analysis
-pH < 4.5 (acute)
-pH 4.5 to 5.5 (SARA)
-few to no protozoa
-foul smelling, gray/yellow fluid
What are the treatment steps for ruminal acidosis?
*restore the rumen
-empty rumen contents
-raise rumen pH
-activated charcoal (true toxins)
-transfaunation
*rehydrate
-oral and IV fluids
*systemic therapy
-antibiotics
-NSAIDs
What are the long term sequelae of ruminal acidosis?
-laminitis
-liver abscess
-caval syndrome
-parakeratosis
-mycotic rumenitis
-polioencephalomalacia
-low butter fat
-poor production
How is ruminal acidosis prevented?
-avoid rapid changes in diet
-avoid feed bunk drama
-maintain adequate amounts of forage
What are the characteristics of rumenitis?
-inflammation of rumen wall following toxic/caustic insult
-almost always associated with ruminal acidosis
-damage to wall of rumen leads to shed of bacteria into circulatory system
-can cause liver abscess, septic renal infarcts, and vegetative endocarditis
Which pathogens are associated with rumenitis?
-Fusobacterium necrophorum (esp. liver abscess)
-Strep. bovis
-Trueperella pyogenes (seen in all abscesses)
Where do bacteria spread to following rumenitis?
-liver
-right side of heart
-lungs
What are the characteristics of vagal indigestion?
-syndrome of motor neuron dysfunction of the forestomachs
-NOT a diagnosis
-many possible etiologies; hardware disease is most common
What are the four types of vagal indigestion?
type 1: failure to eructate
type 2: failure of omasal transport
type 3: failure of abomasal transport
type 4: pregnancy associated
What can cause type 1 vagal indigestion?
-foreign body
-pneumonia
-calf diphtheria
What can cause type 2 vagal indigestion?
-impaction
-traumatic reticuloperitonitis/hardware dz
-foreign body
What can cause type 3 vagal indigestion?
-displaced abomasum
-lymphosarcoma
-ulceration
-impaction
-volvulus of duodenal flexure
What can cause type 4 vagal indigestion?
-late gestation
-diffuse peritonitis
What are the clinical signs of vagal indigestion?
-gradual distention of rumen
-“papple” contour
-homogenization of rumen contents
-anorexia
-bradycardia
-scant mucoid feces
-hypermotile/hypomotile rumen contractions
What causes the following abdominal contours?
A: normal contour
E: vagal indigestion type 2; omasal transport failure
F: vagal indigestion type 3; pyloric outflow obstruction
M: vagal indigestion type 3; abomasal impaction
What is the appearance of type 1 vagal indigestion?
very massive cow; too large to see any papple contour
