11.3.4: Abdominal distension Flashcards
What is the norml ruminal turnover for cattle?
3 contractions (turnovers) in 2 mins
True/false: you can differentiate primary from secondary ruminal contractions on auscultation.
False
What are some differentials for abdominal distension?
- Bloat
- Acidosis
- Oesophageal obstruction
- Pregnancy
- Vagal indigestion
- Urethral obstruction
- GI obstruction, impaction or displacement
- Traumatic reticulitis (TRP)
- Peritonitis
- Ascites secondary to liver/cardiac/renal failure
- Others: clostridial disease, neoplasia, overeating
What colour should normal rumen fluid be? What other parameters can you assess from a sample of rumen fluid?
- Green
- Not brown/red
- Also need to assess under microscope and in lab: test pH, protozoal activity, methylene blue reduction time, chloride concentration
What pH rumen fluid would make you suspicious of SARA?
pH below (i.e. more acidic than) 5.5 = indicative of SARA
What is a normal methylene blue clearance time?
- The ruminal protozoa should clear methylene blue in 5 mins
What does chloride concentration in rumen fluid tell us about the rumen?
Chloride concentrations tells us whether outflow is possible from the rumen
What is frothy bloat and what is it commonly associated with?
Frothy bloat: the formation of stable froth within the rumen. This is a fairy-liquid type foam that stops the cow from being able to eructate. It is predominantly associated with changes in feed.
Describe the pathogenesis of frothy bloat when animals are fed a diet high in legumes
- High threshold stretch receptors inhibit motility
- Less saliva -> increase in rumen liquor viscosity
- Fluid higher in chloroplast membrane fragments and soluble proteins -> prevents reflex relaxation of the cardia -> eructation is not possible
Describe the pathogenesis of frothy bloat when animals are a fed a diet low in fibre and high in concentrates
- Less saliva -> increase in rumen liquor viscosity
- Microbial polysaccharide production
- Polysaccharides + increased liquor viscosity = stable foam
What is another name for primary ruminal tympany?
Frothy bloat
What is another name for secondary ruminal tympany?
Gas bloat
What might cause rumen hypomotility?
- Systemic inflammation
- Increased sympathetic tone
- Rumen distension or acidosis
Treatment of frothy bloat
- Anti-foaming agents e.g. mineral oil, poloxalene (“bloat guard”)
- Rumenotomy decompression (in severe cases)
- Diet management: take off pasture, strip graze, feed hay before going onto grass (buffer feeding so they don’t gorge themselves on clover for example)
- Add long fibre to diet
Describe the aetiology of free gas bloat
- a.k.a. secondary bloat
- There is an inability to eliminate gas by eructation secondary to another condition
What conditions may lead to the development of free gas bloat?
- Obstruction (FB)
- Hypocalcaemia
- Prolonged lateral recumbency
- Vagal nerve damage
- Tetanus
- Actinobacillus
- Outside pressure e.g. carcinoma (neoplasia is rare), bTB
What is vagal indigestion?
- Vagal nerve damage/injury leads to enlarged rumen (rather than bloat)
- Occurs secondary to TRP, actinobacillus (rumen/reticulum), peritonitis, abscessation
- Hinders the passage of ingesta from the reticulorumen, abomasum, or both, resulting in the distension of the abdomen
Clinical signs of vagal indigestion
- Clinical signs are non-specific
- Decreased milk yield, anorexia
- Abnormal faeces
- Recurrent bloating
- Decreased ruminal motility
How can we classify vagal indigestion?
2 forms:
* Anterior functional stenosis
* Pyloric outflow failure
Describe the pathogenesis of anterior functional stenosis (form of vagal indigestion)
- Insufficient excitatory stimuli from vagus nerve
- Decreased motor drive of the primary reticular cycle
- Paralysis of the omasum and reticulomasal orifice
- Substantial reticular adhesions prevent normal ingesta and fluid flow to reticuloomasal orifice
- Decreased/absent flow into the omasum so rumen distends
Describe the pathogenesis of pyloric outflow failure (form of vagal indigestion)
- Accumulation of ingesta in the abomasum and omasum
- Abomasal content enters the rumen
- Severe distension and decrease in forestomach motility
- Increased fluid retention in the rumen
- Marked dehydration and hypochloremic metabolic acidosis
What is choke associated with in cattle and sheep?
- Large quantities of feed and rapid intakes
- Feeding of root crops: potatoes, turnips, apples, fodder beet
- Ingestion of placenta in sheep
Clinical signs of choke in ruminants
- Profuse salivation and bloat
- Distress
- Extended neck
- Coughing
Where are the common sites of obstruction in ruminants with choke?
- Oropharynx
- Thoracic inlet
- Heart base
Basically anywhere the tubes narrow.
Treatment of choke
- Attempt removal using fingers or gentle pressure with stomach tube (using paraffin/cooking oil or lubricant)
- Leave to macerate in rumen if trocar present
- If severe cases, relieve rumen tympany using trocar in left paralumbar fossa
- Oesophagotomy may sometimes be the only option
True/false: choke is common in sheep and cattle but is not considered an emergency as many cases are self-resolving if given time.
False
Choke is common in sheep and cattle, and it is an emergency.
