Lactic Acidosis in Ruminants: Causes, Pathogenesis, and Emergency Treatment

​1. Introduction

​Lactic Acidosis, which is also known as Grain Overload, Rumen Acidosis, or Carbohydrate Engorgement, is considered to be an important metabolic disorder in cattle, sheep, and goats. This condition develops as a result of the sudden ingestion of large amounts of readily fermented carbohydrates like cereal grains. The condition causes the pH in the rumen to drop rapidly, which leads to dehydration and acidosis in cattle.

Lactic Acidosis in cattle

​2. Etiology and Risk Factors

​The main cause of Lactic Acidosis in cattle is the sudden change in the diet without an adequate transition period. The following conditions may cause Lactic Acidosis in cattle:

1.​Accidental exposure to feed containing grains in the feed storage areas.

2.​Sudden introduction of high-concentrate rations in feedlots.

3.​Sudden change from a forage-based ration to a grain-based ration.

4.​Low fiber content in the total mixed ration.

​3. Pathogenesis: The Microbial Shift

​Rumen Microbiota: The rumen in cattle consists of bacteria, protozoa, and fungi. When starch enters the rumen in large amounts, the following effects occur:

​Microbial Proliferation: 

Streptococcus bovis and Lactobacillus multiply rapidly.

Lactic Acid Accumulation: 

The starch is fermented into Lactic Acid, which is much stronger than the normal Volatile Fatty Acids (VFAs).

​pH Drop: 

The pH in the rumen drops below the normal pH range of 6.5-7.0 to below 5.0.

​Osmotic Pressure: 

The osmotic pressure in the rumen increases because of the high acidity. Water is drawn out of the blood and tissues of the animal into the rumen. This dehydrates the system severely and produces the "sloshing" sound in the belly.

​Ruminitis: 

The rumen lining is burned by the acid, allowing the bacteria to enter the bloodstream.

​4. Clinical Signs and Diagnosis

The degree of the signs depends upon the amount of grain consumed.

​Acute Stage:

.Complete loss of appetite (anorexia)

.Abdominal pain

.Distended rumen

Neurological Signs:

.Depression

.Staggering gait (ataxia)

.Inability to stand (recumbency)

​Fecal Changes:

Profuse, watery, greyish diarrhea with a distinctive sour odor

​Physical Exam:

.Tachycardia (increased heart rate)

.Shallow, rapid breathing

Differential Diagnosis Table

Feature	Lactic Acidosis	Milk Fever	Ketosis
Primary Cause	Carbohydrate Overload	Calcium Deficiency	Negative Energy Balance
Rumen pH	Very Low (<5.0)	Normal (6.5-7.0)	Normal/Slightly Low
Typical Odor	Sour/Acidic Breath	No specific odor	Sweet/Acetone Breath

5. Emergency Treatment and Veterinary Management 

Time is of the essence in the treatment of grain overload.

Neutralization of Rumen Acidity: 

Administer antacids such as Magnesium Hydroxide or Magnesium Oxide (500g in 10 liters of water). 

Fluid Therapy: 

Administer large volumes of IV fluids (Isotonic Saline) to combat dehydration. Add Sodium Bicarbonate (5%) IV to neutralize systemic acidosis. 

Rumen Lavage: 

If the above measures fail, a stomach tube can be used to flush out the rumen. 

Transfaunation: 

This method is the most effective in the treatment of grain overload. Take 5-10 liters of rumen fluid from a healthy animal and introduce it into the sick animal to replace the rumen flora.  

Antibiotics:

Penicillin is usually prescribed to prevent the occurrence of secondary liver abscesses due to Fusobacterium necrophorum. 

6. Long-term Sequela (After-Effects) 

If the animal has survived the crisis, the long-term after-effects to be watched out for are:

Laminitis: 

Permanent damage to the hooves. Liver Abscesses: These usually develop weeks after the accident. 

Rumen outflow obstruction: 

Permanent damage to the rumen walls.

7. Conclusion

Lactic Acidosis remains one of the biggest challenges in the management of ruminal metabolism in the modern dairy and feedlot industry. While medical and surgical measures such as rumenotomy and transfaunation have been effective in saving many animals, the damage to the rumen papillae and the liver results in considerable economic loss. For a dairy or feedlot to be economically viable, the management strategy has to change from treatment to dietary management.