Abdominal distension Flashcards
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
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 educate 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
Therapeutics for choke
Spasmolytic IV/IM
- To relax the oesophagus, can help move the FB down
- Hyoscine Butylbromide + Metamizole
– Spasmium comp.
– Licensing:
-> Has license for dairy cows
-> Use in pregnancy after benefit-risk assessment by vet (could potentially be damaging to the foetus but if she’s dying…)
-> As supportive therapy for acute diarrhoea
But, do not use in cases of:
- gastro-intestinal ulceration
- chronic gastro-intestinal disorders
- mechanic stenoses in the gastro-intestinal system
Sedation IM/IV
- Xylazine
– Licensing:
-> Pre-medication for minor superficial operations, painful manipulative procedures and local or regional anaesthesia.
But :
- Increased risk of regurgitation
- Increased risk of recumbency
- Not for use in latter stages of pregnancy except at parturition
- alpha-2s decrease GI transit so could cause a different type of bloat - so O expectations…
Calves - ruminal bloat
- Usually slightly older calves
– Poor oesophageal groove closure - Often just after weaning
- Causes not well understood
– Related to poor rumen development
– Clostridia could be related
Calves - ruminal bloat CS
- Much more chronic
- Diarrhoea, poor hair coat, decreased DLWG
- Often recurrent bloat
- May follow concentrate feeding
- Waxing and waning LHS bloat (as chronic)
Calves - ruminal bloat management
- Short term deflate with stomach tube
- Long term fistula or trocar
- ^ long term management as doesn’t solve the cause
Abomasal Bloat - signalment
- Pre-weaned calves
- 1-3 weeks old
- Usually dairy
Abomasal Bloat - cause
- Rapid gas production in abomasum
- Excessive fermentation of simple carbs
- Overgrowth of gas producing bacteria
- Clostridia may be related?
Abomasal bloat - clinical exam
- Splashing on abdominal percussion (high pitched splash - like an RDA in an adult cow)
- Right ventral abdominal distension
- Colic
Abomasal bloat - tx
- Relieve bloat (tube [putting in a dog sitting position can help] or needle [risk of viscous leaking into the abdomen and causing peritonitis if do transcutaneous needle])
- IVFT
- Antibiotics (penicillin)
- Hyoscine
- NSAIDs
- Chance of secondary ulcers from tx
Abomasal bloat - management
- Review milk feeding
- Secondary abomasal ulceration?
Left Flank Laparotomy
- Clip, block and prep
– Remember to “sweep” off transverse processes (lots of dust and shit accumulates here so need to remove it before surgery) - Incise in paralumbar fossa
– 4cm caudal to ribs
– Too close to ribs = hard to close
– Incise skin, external and internal abdominal oblique muscles, transversus abdominis and peritoneum - Sheep = same but lateral recumbency and do big enough clip to remove wool from the incision, also use a drape (rarely used in cows)
Cranial abdomen exploration
- Pylorus
- Abomasum
- Omasum
- Reticulum
Caudal abdomen exploration
- Bladder
- Uterus
- Left kidney
- Intestines
Rumenotomy - indications
- Adhesions suspected
- TRP, foreign body, toxins, frothy bloat
- Access to rumen and reticulum
Rumenotomy - approach
- Restraint - don’t want the animal going down (contamination, poor visualisation)
- Same as laparotomy
- Suture rumen to body wall
– Partial thickness
– Short runs of Cushing pattern
-> 3 or 4 separate lines of suture
-> 1 big suture would become too tight and if ti comes undone the whole thing will come undone
-> Stay sutures don’t really work
Rumenotomy - other possibilities
- Stay sutures
- Weingarth apparatus
- Wound edge protector
Rumenotomy - peri-op considerations
- Clean contaminated surgery
- Perioperative antimicrobials and NSAIDs
- Restraint!
Rumenotomy - forming a seal
- the seromuscular layer of the rumen is sutured to the skin in an inverting pattern to create seal
- blood that has accumulated at the ventral aspect of the incision is left in place as it helps create a better seal
- means that the ruminal contents come out of the body rather than into the cow
Rumenotomy - preventing abdominal contamination
- Gabel rumen retractor (rumen board)
– used to prevent rumen retraction and abdominal contamination during rumenotomy
– holds the rumen exterior to the body - Wound edge protector
– a plastic drape that has an expandable rubber ring, holding the drape open on the interior of the rumen
– the outside of the drape is adhered to the patient
– it protects the surgical site from contamination from the rumen contents
Rumenostomy
- Recurrent bloat?
- Self retaining trocar preferrable
– But peritonitis risk
– Red Devil: not a secure opening, will eventually fall out - Similar to laparotomy except only small circle of skin incised
– Rumen stay sutured to body wall
– Small circle of rumen mucosa removed
– Rumen wall sutured to body wall in everting pattern
-> Horizontal/vertical mattress - Gradually granulate and close
