11.3.4: Abdominal distension

Question 1

What is the norml ruminal turnover for cattle?

Answer 1

3 contractions (turnovers) in 2 mins

Question 2

True/false: you can differentiate primary from secondary ruminal contractions on auscultation.

Answer 2

False

Question 3

What are some differentials for abdominal distension?

Answer 3

• 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

Question 4

What colour should normal rumen fluid be? What other parameters can you assess from a sample of rumen fluid?

Answer 4

• Green
• Not brown/red
• Also need to assess under microscope and in lab: test pH, protozoal activity, methylene blue reduction time, chloride concentration

Question 5

What pH rumen fluid would make you suspicious of SARA?

Answer 5

pH below (i.e. more acidic than) 5.5 = indicative of SARA

Question 6

What is a normal methylene blue clearance time?

Answer 6

• The ruminal protozoa should clear methylene blue in 5 mins

Question 7

What does chloride concentration in rumen fluid tell us about the rumen?

Answer 7

Chloride concentrations tells us whether outflow is possible from the rumen

Question 8

What is frothy bloat and what is it commonly associated with?

Answer 8

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.

Question 9

Describe the pathogenesis of frothy bloat when animals are fed a diet high in legumes

Answer 9

• 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

Question 10

Describe the pathogenesis of frothy bloat when animals are a fed a diet low in fibre and high in concentrates

Answer 10

• Less saliva -> increase in rumen liquor viscosity
• Microbial polysaccharide production
• Polysaccharides + increased liquor viscosity = stable foam

Question 11

What is another name for primary ruminal tympany?

Answer 11

Frothy bloat

Question 12

What is another name for secondary ruminal tympany?

Answer 12

Gas bloat

Question 13

What might cause rumen hypomotility?

Answer 13

• Systemic inflammation
• Increased sympathetic tone
• Rumen distension or acidosis

Question 14

Treatment of frothy bloat

Answer 14

• 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

Question 15

Describe the aetiology of free gas bloat

Answer 15

• a.k.a. secondary bloat
• There is an inability to eliminate gas by eructation secondary to another condition

Question 16

What conditions may lead to the development of free gas bloat?

Answer 16

• Obstruction (FB)
• Hypocalcaemia
• Prolonged lateral recumbency
• Vagal nerve damage
• Tetanus
• Actinobacillus
• Outside pressure e.g. carcinoma (neoplasia is rare), bTB

Question 17

What is vagal indigestion?

Answer 17

• 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

Question 18

Clinical signs of vagal indigestion

Answer 18

• Clinical signs are non-specific
• Decreased milk yield, anorexia
• Abnormal faeces
• Recurrent bloating
• Decreased ruminal motility

Question 19

How can we classify vagal indigestion?

Answer 19

2 forms:
* Anterior functional stenosis
* Pyloric outflow failure

Question 20

Describe the pathogenesis of anterior functional stenosis (form of vagal indigestion)

Answer 20

• 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

Question 21

Describe the pathogenesis of pyloric outflow failure (form of vagal indigestion)

Answer 21

• 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

Question 22

What is choke associated with in cattle and sheep?

Answer 22

• Large quantities of feed and rapid intakes
• Feeding of root crops: potatoes, turnips, apples, fodder beet
• Ingestion of placenta in sheep

Question 23

Clinical signs of choke in ruminants

Answer 23

• Profuse salivation and bloat
• Distress
• Extended neck
• Coughing

Question 24

Where are the common sites of obstruction in ruminants with choke?

Answer 24

• Oropharynx
• Thoracic inlet
• Heart base

Basically anywhere the tubes narrow.

Question 25

Treatment of choke

Answer 25

• 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

Question 26

True/false: choke is common in sheep and cattle but is not considered an emergency as many cases are self-resolving if given time.

Answer 26

False
Choke is common in sheep and cattle, and it is an emergency.