Indigestion in ruminant

1. Definition

Tympany, commonly referred to as bloat, is a condition in ruminants characterized by excessive accumulation of gas in the rumen and/or reticulum. It results in distension of the left paralumbar fossa and can lead to respiratory distress, decreased cardiac output, and death if untreated.

2. Classification

Tympany is classified into two main types:

A. Primary (Frothy) Bloat

• Caused by ingestion of legumes (e.g., alfalfa, clover), which produce a stable foam that traps fermentation gases in the rumen.
• Foam prevents gas from being eructated (belched).
• Common in pasture-fed cattle.

B. Secondary (Free-Gas) Bloat

• Results from physical or functional obstruction of the esophagus or failure of normal eructation.
• Causes include:
• Esophageal obstruction (e.g., foreign body, tumors)
• Vagal indigestion
• Hypocalcemia
• Lateral recumbency (as during anesthesia)
• Tetanus or pharyngeal paralysis

3. Epidemiology

• Affects cattle more commonly than sheep or goats due to grazing behavior and rumen capacity.
• Young animals and high-producing dairy cows are at higher risk.
• Frothy bloat is more common during spring and early summer with lush (juicy) pasture growth.

4. Etiology and Risk Factors

5. Pathophysiology

• Rumen fermentation naturally produces gas (CO₂, CH₄, N₂).
• Normally, gases are eliminated by eructation.
• When eructation is impaired:
• Intraluminal pressure rises → compression of diaphragm → dyspnea.
• Venous return to heart decreases → hypotension, shock.
• Death occurs from asphyxiation or cardiovascular collapse.

In frothy bloat, gas is trapped in a stable foam; in free-gas bloat, gas is not trapped but cannot escape.

6. Clinical Signs

In sheep and goats, signs are similar but may progress more rapidly in lambs/kids.

7. Diagnosis

A. Clinical Diagnosis

• History of sudden onset after pasture change.
• Left-sided abdominal distension ("Papple" shape in advanced cases).
• Ping sounds and fluid/gas on auscultation.

B. Diagnostic Procedures

• Passing a stomach tube:
• If gas escapes freely → free-gas bloat
• If no gas escapes → likely frothy bloat
• Rumen fluid examination:
• Frothy content in primary bloat.
• pH may be reduced in grain-associated bloat.

8. Treatment

A. Emergency Decompression

• Stomach tube: Immediate relief in free-gas bloat.
• If unsuccessful: Trocarization of left paralumbar fossa using trocar and cannula.

B. Antifoaming Agents (Frothy Bloat)

• Poloxalene, mineral oil, vegetable oils (sunflower, soybean): Break down stable foam.
• Administer orally via stomach tube.

C. Other Supportive Treatments

• Calcium borogluconate (if hypocalcemia suspected).
• Broad-spectrum antibiotics (if secondary infection or TRP involved).
• NSAIDs or corticosteroids in severe inflammation.

9. Prevention

A. Pasture Management

• Avoid grazing hungry animals on lush legume pastures.
• Mix grasses with legumes to reduce risk.
• Feed dry hay before pasture turnout.

B. Feed Management

• Avoid finely ground grains.
• Introduce dietary changes gradually.
• Use ionophores (monensin, lasalocid) in feed: reduce foam-producing bacteria.

10. Complications

• Aspiration pneumonia: If animal regurgitates or is in lateral recumbency.
• Shock and death: Rapid onset in severe cases.
• Chronic rumenitis: From prolonged pressure and impaired motility.

11. Prognosis

• Good if treated early, especially in free-gas bloat.
• Poor in cases of chronic obstruction or when treatment is delayed.
• Recurrent cases suggest underlying anatomical or neurological issue.

13. Summary Table