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Understanding Hindgut Acidosis in Horses: Causes, Symptoms, and Dietary Solutions

Understanding Hindgut Acidosis in Horses: Causes, Symptoms, and Dietary Solutions

What is Acidosis in horses

Acidosis is horses occurs in the hindgut when the horse is fed too much grain.  Horses have a limited capacity to digest starch in the stomach and intestines. Feeding too much starch (high NSC) can "overload" the digestive capacity in the intestines and the excess starch will flow undigested to the hind gut, where it is fermented by the microbial organisms that live in the hind gut. These organisms normally produce volatile fatty acids (VFA) that are used by the horse for energy. They also produce lactic acid which in large amounts causes a rapid decrease in pH (<4), i.e. increased acidity or acidosis, which is the same as occurs in feedlot cattle.

The rapid decline in pH causes death of the microbial organisms, release of microbial toxins, and reduced fermentation in the hindgut. These conditions can lead to laminitis and colic,  reduced appetite, and deficiencies in B Vitamins.

Signs Your Horse May Have Acidosis

  • Feet Problems: Lameness, laminitis (founder), ringbone, or navicular disease. 
  • Tail Rubbing: Irritation caused by acidic droppings. 
  • Loss of Appetite and Diarrhea: Discomfort and digestive upset. 
  • Rancid Smell from Droppings: Presence of dead microbial flora. 
  • Mouth Issues: Sores and teeth sensitivity, especially when eating hay

Common Causes of Acidosis

The primary cause is the rapid introduction of grains into a horse’s diet. 
Grains increase the starch content beyond the digestive capacity, resulting in bacterial changes and lactic acid build-up in the hindgut, ultimately causing acidosis.

Dietary Solutions to Managing Acidosis - Why Coolstance copra

Low Starch and Sugar (NSC) Diets: Choose grain-free diets with less than 11% NSC
Coconut Meal: A 100% grain-free alternative with low starch and sugar levels (NSC 11%).
Contains digestible fibre, protein and oil.

Recommended Feeding Practices 


Horses need digestible energy (DE) for body maintenance and performance. While hay and pasture provide maintenance energy, performance horses require high-DE feeds. Traditional feeds high in grains can lead to metabolic disorders, including acidosis, due to overfeeding. 

 Choose feeds such as Coolstance copra with a balanced profile of non-NSC (oil and fibre) and NSC (sugar and starch) energy, with less than 12% total NSC to help prevent acidosis. 

Provide a supplement such as Stance Equitec Ulcabuf to maintain normal hindgut pH.


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