FieldDxSubacute Ruminal Acidosis / Grain OverloadClinical signs, differential diagnosis, treatment and prevention in cattle and sheep.
Overview
A digestive disturbance from excess rapidly fermentable carbohydrate reaching the rumen. A sudden large intake of grain or other rapidly fermentable carbohydrate, causing excess rumen lactic acid production and a drop in rumen pH. Marked emergency in FieldDx. Zoonotic: this condition can pass to people.
Clinical signs
- Chemical rumenitis; absorbed lactate (particularly D-lactate) causes lactic acidosis and acidaemia.
- Metabolic acidosis, dehydration, hemoconcentration, cardiovascular collapse, renal failure, muscular weakness, shock, and death in severe cases.
Predisposing factors
- A sudden increase in fermentable carbohydrate (grain overload) drops ruminal pH.
Treatment
- 5% sodium bicarbonate IV, 5 L per 450 kg, over about 30 minutes.
- Over the following 6-12 hours, a balanced electrolyte solution or 1.3% sodium bicarbonate IV, up to 60 L per 450 kg.
- Empty the rumen, then re-inoculate it; oral antacids are usually unnecessary and can be undesirable once IV bicarbonate has been given.
Drugs mentioned: Sodium Bicarbonate
Prevention
1. Allow time for the rumen to adapt to high-grain diets, and limit rapidly fermentable carbohydrate. 2. Balance fibre and non-fibre carbohydrate in the ration; avoid concentrate-heavy, fibre-deficient rations, including before calving. 3. Manage feed bunks to limit large meals, and avoid feed deprivation followed by overconsumption. 4.
Source
MSD Veterinary Manual — Subacute Ruminal Acidosis in Cattle and Sheep (accessed 2026-08-10)
MSD Veterinary Manual — Subacute Ruminal Acidosis in Cattle and Sheep (accessed 2026-10-29)
Condensed and attributed, never reproduced whole. Open the full entry in the app.