2.6 Cow abdominal problems, 2.7 LDA

Rumen optimal pH, substances that decrease it, and VFAs that predominate in both scenarios

• 6.2-7

  • Ethanoic acid (acetate)

• pH decreases with starch and sugar

  • Propanoic acid (propionate) + butanoic acid (butyrate)

3 reasons for acute ruminal acidosis

EMERGENCY - poor/guarded prognosis

• Sudden ingestion of large amounts of fermentable carbs (eg lots of grain)

• Concentrate overfeeding

• Sudden lack of forage/straw bedding (can be eaten)

4 treatments for acute rumenal acidosis

• Slow IV of 5% NaOH (5L/450kg over 30 mins)

• IV of isotonic (0.9%) NaCl (150mL/kg over 6-12h)

• Oral Mg(OH)2 (500g/450kg)

• Rumenotomy or stomach tube rumen lavage

  • Traumatic procedure, not very successful

Cause of subacute rumen acidosis

Diet over long to medium term:

• Suboptimal fiber levels and/or

• High carb (grain) levels

Signs of SARA (4)

• Low milk fat/yields

• Inappetance

• Occasional laminitis

• Repeated epistaxis or haemoptysis (coughing up blood)

  • Caudal vena cava syndrome from inflamed rumen → liver

  • Basically diagnostic of chronic SARA

How does SARA lead to caudal vena cava syndrome? (5)

• Rumen wall damage → bacteria go into portal circulation to liver

• Or direct transfer from cranial rumen to liver where they touch

• Liver abscesses

• Septic embolism passes to caudal vena cava → lungs

• Damage to pulmonary artery (and smaller vasculature)

Describe the 3 stages of distension seen in rumen bloat (tympany).

• Mild - left sublumbar fossa

• More - whole left flank

• Severe - distended whole abdomen

Why does rumen bloat sometimes lead to sudden death?

Rumen pushes against diaphragm + lungs → respiratory distress

Name 3 plants which can cause frothy bloat.

(soluble leaf proteins → foaming properties:)

• Clovers (the worst one)

• Legumes

• Alfalfa

• (Cereal rich diets or rich pastures)

Name 2 grazing methods to minimise risk of frothy bloat.

• Buffer feeding - feed before turning out to decrease risk of lush pasture overfeeding

• Restriction (eg with temporary fence or strip grazing) so less rich pasture can be grazed

Name 3 ways to treat frothy bloat.

• Remove cow from feed source

• Antifoaming agent or surfactant

  • Poloxalene (bloatguard)

  • Mineral or corn oil

  • BIRP (simethicone)

• Sternal recumbency to encourage eructation

List 4 causes of free gas (gaseous) bloat.

• Excessive carb intake → acidosis

• Oesophageal obstruction

  • Eating quickly, esp when trough space is limited

• Milk fever (hypocalcaemia)

• Lateral recumbency (blocks cardiac sphincter)

List 4 methods of treating gaseous bloat.

• Ca2+ injection - stimulates rumenal contractions and eructation

• Sit the cow up to potentially unblock cardiac sphincter

• Relieve gas

  • Stomach tube

  • Trocar and cannula on L paralumbar fossa

• Rumenotomy

  • Especially useful if rumenal acidosis is the cause

List 4 potential causes of oesophageal obstruction (aside from the obvious one).

• Lesions of oesophageal groove → damage to vagus (vagal indigestion syndrome)

• Blockage of cardiac sphincter (Actinobacillus or papilloma)

• Tetanus

• (theoretically enlarged mediastinal lymph nodes)

List 3 potential signs of traumatic reticuloperitonitis.

• Local/diffuse peritonitis

• Pericarditis (if pericardium is penetrated) → heart failure

  • Palpate jugular pulse 

  • Splashing sound over heart

• Liver abscesses

List 3 tests potentially used to diagnose traumatic reticuloperitonitis.

• Withers pinch → pain vocalisations

• Pole test → metal pole pulled up below sternum → pain vocalisations

• Eric williams test (difficult) → pain signs just before reticulorumen cycle

List 4 treatments for traumatic reticuloperitonitis.

• Conservative

  • Tie animal up with front feet higher than back feet

  • Parenteral (non GIT) antibiotics

  • Pain relief

• Rumenotomy

• Magnet (bolus gun) into reticulum - only magnetic metals!

• (slaughter)

Describe the mechanism of LDA.

Abomasum (normally on right) slides underneath rumen → trapped between rumen and left body wall

Which cows does LDA typically happen in?

High producing dairy cows within 6 weeks after calving

List 9 causes of LDA.

• Excess VFAs from rumen to abomasum → makes it floppy and mobile

• Poor management over transition period

  • Low → high energy diet change made too quickly

  • Insufficient fiber

• Bloat

• Milk fever

• Retained foetal membranes

• Rumen collapse

• Pneumoperitoneum

• Vagal indigestion syndrome

• Genetic factors

LDA clinical signs (4)

• Raised blood/urine ketones

• (variable) drop in milk yield

• (variable) change in appetite

• (variable) decreased BCS and reduced rumen contractions

LDA treatment methods (4)

• Conservative - roll slowly onto right lateral recumbency and then onto back

• Roll + toggle - suture abomasum back into place

  • toggle = plastic on end of suture

• R flank laparotomy with R omentoplexy/pyloroplexy (Utrecht method) → hard

• Paramedian laparotomy + ventral abomasoplexy + omentoplexy (hard)

Describe the mechanism of RDA and how it can lead to severe disease.

• Abomasum moves dorsally and then undergoes torsion or volvulus → trapped between liver and body wall

• Ischaemic necrosis due to blood supply cutoff

List 6 potential pathologies that may present as pings.

• Rumen bloat (L)

• LDA (L)

• RDA (R)

• Abomasal torsion (R)

• Caecal dilation and torsion (R)

• Gas in spiral colon (R, no clinical significance)

Where does pinging happen during caecal dilation? What potential risk is there?

• Caudal right paralumbar fossa

• Volvulus in free caudal end of caecum → ischaemia

Treatment of caecal dilation

• Medical fluids + high fiber diet

• Surgery if persistent

Treatment of caecal volvulus

Surgical draining - cut into apex

List the steps of a right sided omentoplexy. (5)

• Reach cranially across rumen with sterile hand

• Pop L abomasum to let gas out

• Grab abomasum from below rumen by hand

• Put it back on R side

• Stitch omentum to muscle layers in incision

  • ‘Sow’s ear’ floppy flap of omentum preferred for suturing

  • Holds the abomasum into place

Aftercare for right sided omentoplexy (5)

• Isolation for rest

• Antibiotics - abdominal contamination

• Fiber only diet for 5 days

• Monitor

  • Pneumoperitoneum can present as a ping but is harmless

• Pain relief (not for too long)

  • Not NSAIDs - irritates abomasum

In ketosis (acetonaemia), which 2 ketone bodies increase in the blood?

• Beta hydroxybutyrate (3 hydroxybutanoate)

• Acetoacetate (3 oxobutanoate)