Lecture 2 Flashcards
What cycle is the main eructation cycle?
Secondary Cycle
When does erructation occur?
At the end of the caudal to cranial contraction of the ventral sac
Explain the secondary cycle
Moves gas in rumen towards cardia
Animal inhales and creates negative pressure in thorax which draws gas into esophagus
Cranial to Caudal movement in ventral sac then caudal to cranial movement in dorsal sac
Explain Eructation
Microbes produce gas
Gas build up occurs in dorsal rumen
Secondary contraction moves gas to the cardia region of reticulum
Gas causes reflex opening of cardia and caudal esophagus
Animal inhales creating negative pressure in thorax drawing gas into esophagus
Some gas exhaled directly some enters lungs to be exhaled on next breath
What can occur to gas during eructation
Can be absorbed into blood
ie. ketones in blood
What feed increases rumination?
High-roughage diets
- have to break it down more
WHat is rumination and indicator of?
Good Health
What is released during rumination?
Endorphins
Sequence of events of rumination
Just before primary contraction, reticulum contracts
Negative pressure created by inhalation while airways are closed
Cardia and distal esophageal sphincter relax, drawing cud into esophagus
Esophagus contracts cranially (rvs peristalis) cud travels toward mouth
Tongue raised and squeezes fluid out of cud and fluid swallowed
Solid cud is chewed for 10-60sec
Two outcomes of rumination
Buccal receptor stimulation
- increased salivation and rumen movement
- More mixing of ingesta
Smaller particle size
- Greater surface area for microbes
- Greater chance of passing omasum
5 Ways to examine rumen motility
Examine rate and strength of contractions
Visual exam
Auscultation
External Palpation
Rectal Exam
What do we look for upon a visual exam
See undulations of L. Paralubar fossa
Look for bloat
What do we ausculatate for?
Loud primary cycle
Fluid Splashing - Occurs at onset of bloating
Tinkling or tinging - definite indication of bloat
What do we externally palpate for
Doughy feel = healthy
What do we feel for upon rectal examination?
Feel caudodorsal rumen contractions
What is hypomotility?
Less than normal motility
What is atony or stasis?
No motility
Distinguish between primary and secondary clinical signs
Primary - something wrong with rumen
Secondary - Other part of body in pain
5 mechanisms of decreased motility
Direct Depression of gastric center
Decrease stimulatory inputs from peripheral receptors to gastric center
Increase inhibitory inputs from peripheral receptors to gastric center
Failure of neuromuscular transmission
Increased sympathetic stimulation
10 Conditions causing decreased motility
Animal is not eating
Displaced Abomasum
Traumatic Reticuloperitonitis
Bloat
Rumen Impaction
Ruminal Acidosis
Hypocalcemia
Vagal Indigestion
Stress/Fear
Drugs
What receptors does lack of eating affect to cause decrease in rumen motility
Decrease in buccal mechanoreceptor stimulation
Decrease reticulorumen tension receptor stimulation
Decrease epithelial receptor stimulation, decreases rumination
How does an LDA or RDA decrease rumen motility?
Abomasum distended with air or fluid
Stimulation of abomasal tension receptors
Incrases inhibitory inputs to gastric centre
All of this causes pain
What is hardware disease also known as?
Traumatic Reticuloperitonitis
How does traumatic reticuloperitonitis cause a decrease in rumen motility?
Direct depression of gastric center
- Pain
- Acute phase proteins (inflammation and fever)
- Lack of appetite
