Abdominal distension Flashcards
(43 cards)
All clinical exams should include assessment of rumen:
- shape
- fill
- motility
Rumen contour
= Shape
- Early in exam
- From a distance
- Rear and side of cow
- Gaunt, normal or distended
Rumen motility
- Simultaneous auscultation and palpation
- Count contractions
- Primary and secondar contractions not differentiated
- normal = 3 contractions in 2 minutes
Hypermotility
- Relatively uncommon finding on clinical exam
– Early rumen distension -> as stretch receptors stimulated
– Increase in primary contractions as result
-> Physiologically normal response to a large meal - Contractions cease if distension continues
– Causes of distension to follow - More than 5 contractions in 2 minutes = hypermotility/hypercontractility
Hypomotility - what animals is it more common in? potential causes?
Much more common in unwell ruminants
- Systemic inflammation
- Increased sympathetic tone (due to pain)
- Rumen distension or acidosis
Differential diagnoses: Abdominal distension
- Bloat (frothy or free gas?)
- Acidosis
- Oesophageal obstruction (choke - feed source?)
- Pregnancy (gravid uterus +/- oedema?) (ddx: hydros, pre-pubertal tendons rupture)
- Vagal indigestion (ruminal atony)
- Urethral obstruction (+/- ruptured urethra)
- GI obstruction, impaction or displacement
- Traumatic reticulitis/TRP
- Peritonitis
- Ascites (liver, cardiac or renal failure; hypoproteinaemia)
- Miscellaneous (clostridial dz, neoplasia, overeating etc)
Diagnosis - distance exam
- Dull/depressed
- History of inappetence
- Decreased productivity
- Silhouette
– Rear and side
Diagnosis - TPR
- Heart rate and resp rate vary massively
– Depending on cause - Temperature usually WNL
– Unless infectious cause
Diagnosis - abdominal exam
- Ausculatation
– Rumen contractility - Percussion
- Succussion
- Rectal examination
– Faecal abnormalities?
– Palpation of rumen
Ancillary diagnostic testing
Rumen fluid analysis
- Colour, pH, protazoal activity, methylene blue reduction time, chloride concentration
- collect via orogastric tube, or rumenocentesis
- want to see a nice variation of big active protozoa
- protozoa in rumen should change methylene blue colourless in 2 mins
- increased chloride concentration due to acid secretion from the abomasum, if have pyloric outflow obstruction would get HCl in the rumen -> uncommon but useful to test for
Blood chemistry profiles
- Metabolic state?
Ultrasonography
Rumenotomy
What is bloat?
- Ruminal dilation or abdominal distension?
- Rumen most commonly responsible
- Ruminal tympany = same thing
- Primary = frothy bloat
- Secondary = gassy bloat
- Emergency -> will suffocate, lack of venous return
Frothy Bloat - definition & aetiology
- Formation of stable froth in rumen as a result of diet
- Usually associated with lush pasture, clover and legumes
- Fatal
– Severe distension -> Compression of thoracic viscera - Cattle > sheep
– Same presentation in sheep
– Easily missed in heavily fleeced sheep
Frothy Bloat: Pathophysiology
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 cardia -> eructation not possible
Low fibre and high concentrates diet
- Less saliva -> increase in rumen liquor viscosity
- Microbial polysaccharide production
- Polysaccharides + increased liquor viscosity = stable foam
- Stable foam -> can’t eructate so gas trapped below it
Frothy bloat - CS & ddx
CS
- Abdominal enlargement of left-hand side when viewed from rear
- Colic
– Kicking, treading, lying down and rising, vocalisation
– Stretched stance, rear feet placed far behind
- Decreased rumen motility
- Beware heavily fleeced sheep
Ddx
- Stomach tube passes but doesn’t decompress (tube goes straight into the foam -> doesn’t reach the gas
Frothy bloat: Treatment
- Anti-foaming agents (e.g. Mineral oil, poloxalene – “BloatGuard”)
– lowering the surface tension of bubbles -> they burst and go back to a liquid -> the gas can escape
– vegetable oil is a good alternative - Rumenotomy decompression
– Severe cases
– (prognosis?)
– cut into the rumen just behind the last rib at the highest point of the swelling (hand down from the paralumbar fossa) with a sterile knife
-> not ideal as will probs get a localised peritonitis but won’t die from this - Diet management:
– Pasture: take off pasture, late morning grazing, strip graze, feed hay before going onto grass
– Add long fibre to diet
– Farmers often put blood guard into pasture water supply
Free gas bloat - definition and aetiology
Secondary: inability to eliminate gas by eructation secondary to another condition
- Obstruction: foreign body (may be palpable)
- Hypocalcaemia (lose contractions so unable to eructate, would have lots of other issues evident)
- Prolonged lateral recumbency
- Vagal nerve damage
- Tetanus (rigidity, protrusion 3rd eyelid, hyperesthesia, locked jaw)
- Actinobacillus (can cause granulomas anywhere in the GIT, which would cause pressure
- Outside pressure (carcinoma, papilloma, EBL, bTB)
Vagal nerve damage/injury - ‘Vagal indigestion’
enlarged rumen>bloat
- Secondary to hardware disease/TRP, actinobacillosis (rumen/reticulum), peritonitis, abscessation
- characterized by dysfunction of reticulorumen
- hinders the passage of ingesta from the reticulorumen, abomasum or both, resulting in the distension of the abdomen
any problem anywhere down the nerve will cause a problem to where that nerve is controlling
Vagal nerve damage/injury - CS
non-specific
- Decreased milk yield, anorexia
- Abnormal faeces
- Recurrent bloating
- Decreased ruminal motility
Vagal Indigestion - 2 forms
- Anterior (proximal) functional stenosis
- Pyloric (caudal) outflow failure
Vagal indigestion - anterior functional stenosis
- insufficient excitatory stimuli from vagus nerve ->
- decreased motor drive of the primary reticular cycle ->
- paralysis of omasum and reticulo-omasal orifice ->
- substantial reticular adhesions prevent normal ingests and fluid flow to reticulo-omasal orifice ->
- decreased/absent flow into omasum so rumen distends
- wire top cause
Vagal indigestion - pyloric outflow failure
- accumulation of ingests in abomasum and omasum ->
- abomasal content enters the rumen ->
- severe distension and decrease in forestomach motility ->
- increased fluid retention in rumen ->
- marked dehydration and hypochloremic metabolic alkalosis
- e.g. LDA - stretching and damaging the vagal nerve
Choke
- Common in sheep and cattle
- Large quantities of feed, rapid intakes
- Root crops
– Potatoes, turnips, apples, fodder beet etc - Placenta (sheep)
Diagnosis = history and CS
EMERGENCY
- time when could get farmer to put sterile knife into rumen to decompress it
Choke CS
- Profuse salivation and bloat
- Distressed, extended neck, coughing
- Obstruction sites:
– Oropharynx, thoracic inlet, heart base
– Palpable/pass stomach tube
Choke: Treatment
- Attempt removal using fingers or gentle pressure with stomach tube (using paraffin/cooking oil or lubricant)
- Leave to macerate if rumen trocar/red devil is present
- If severe relieve rumen tympany
- Trocar and cannula in left paralumbar fossa
- Oesophagotomy?
– jugular, carotid, vagus nerve very close so care
– manage client expectations
