Diseases of the Abomasum (TV4101, Lecture 5 Notes)

List key features of the GIT clinical examination

- Visual assessment of oral cavity and palpation of the tongue

- Visual examination of left abdomen

- Palpation

- Auscultation

- Percussion and simultaneous auscultation

- Ballottement and simultaneous auscultation (succussion)

- Rectal examination

List additional tests of the GIT clinical examination

- Grunt (pain) test

- Pass a stomach tube

- Obtain and analyse a rumen sample (rumenocentesis)

- Obtain and analyse peritoneal fluid (abominocentesis)

- Carry out laboratory work

- Undertake diagnostic imaging

- Carry out an exploratory laparotomy

List causes for left-sided ping

- Left-displaced abomasum

- Atonic rumen (gas/fluid interface)

- Pneumoperitoneum, gas in peritoneal cavity following surgery (rare)

- Physometra, air in uterus (very rare)

*Distinguish with stomach tube test, rectal exam (differentiate rumen contents) and fluid aspiration (check pH).

List causes for right-sided ping

- Dilatation and volvulus, or torsion of caecum

- Intestinal tympany (i.e. post-partum ileus secondary to abomasal or forestomach stasis)

- Torsion of root of mesentery or intussusception

- Torsion of the coiled colon

- Pneumoperitoneum, pneumorectum, or gas-distended uterus

- Distension of proximal colon (common)

Discuss left displaced abomasum (LDA)

- Common in high-producing dairy cattle after calving

- Increased risk with grain-fed animals

- Abomasum becomes enlarged with accumulation of fluid and gas, causing mechanically displacement from its normal position to left side of abdominal cavity between rumen and left abdominal wall

List clinical signs of left displaced abomasum (LDA)

- Present with weight loss post-calving and low milk production (i.e. gaunt appearance)

- Dilated abomasum may be visible as a small bulge behind last rib in paralumbar fossa (not palpable on rectal examination)

- Decreased rumen contractions with 'ping' on percussion (over left-side 9-12th rib) and 'tink' on succussion

- Biochemical changes = dehydration, metabolic alkalosis, hyperchloremic and hypokalemic

List risk factors for left displaced abomasum (LDA)

- Involuting uterus (i.e. space not consumed by rumen)

- Stretch of omentum attached to abomasum

- Decreased food intake during peri-parturient period with reduced rumen volume

- Abomasal atony with increased volatile fatty acids and decreased smooth muscle tone

- Gases trapped in abomasum

- Excess concentrates prior to calving result in decreased rumen fill

- Minimal concentrate prior to calving results in failure of rumen papillae to develop which is needed to increase absorptive capacity

Discuss correction of left displaced abomasum (LDA)

Minimally invasive (typically unsuccessful)

- Rolling

- Percutaneous 'blind' tacking

Open procedures

- Right paralumbar fossa omentopexy

- Left paralumbar fossa omentopexy/abomasopexy

- Right paramedian abomasopexy (recumbent approach)

Discuss supportive treatment of left displaced abomasum (LDA)

- Oral or systemic calcium to correct hypomotility

- Oral electrolytes (dehydrated animals)

- Ketosis treated with oral propylene glycol and IV dextrose

- NSAIDs

- Antibiotics (concurrent infections) prior to surgery

Discuss right-sided abomasal dilation and volvulus

- Abomasal hypomotility associated with hypocalcaemia, high-concentrate or low-roughage diets

- Atony of abomasum followed by accumulation of feed, fluid and gas, causing grossly distended organ

- Abomasum displaced dorsally on right side of abdomen

- Post dilatation/displacement the distended abomasum may rotate (180-270°) around an axis, causing complete luminal obstruction and irreversible neurovascular damage

List clinical signs of right displaced abomasum (RDA)

- Early similar to LDA (i.e. weight loss, low milk, not fully responding to other treatments and disinterested in grain)

- Reduced faeces

- Dull and afebrile

- Varying ketosis

- Elevated HR

- Abdominal pain and distension

- Decreased, weak rumen contractions with 'ping' on percussion (over right-side under last five ribs) and 'tink' on succussion

*Poor prognosis with HR > 120bpm and > 15% dehydration.

Discuss correction of right displaced abomasum (RDA)

- Right flank omentopexy or pyloropexy

- Right-paramedian abomasopexy (recumbent animal)

Discuss supportive treatment of right displaced abomasum (RDA)

- Oral electrolytes (dehydrated animals)

- Ketosis treated with oral propylene glycol and IV dextrose

- NSAIDs

- Antibiotics (concurrent infections) prior to surgery

Discuss abomasal ulceration

- Common in high-producing dairy cattle due first 6w lactation or with an increased fibrous diet

- Erosions and non-perforating ulcers (subclinical), ulcers with profuse intraluminal haemorrhage, perforated ulcers with local peritonitis or perforated ulcers with diffuse septic peritonitis

- Present with impaired appetite/rumen function, decreased milk yield, loss of condition, intermittent diarrhoea with black tarry feaces, ketosis, pain, pale MM and collapse

- Provide supportive therapy (NSAIDs contraindicated)