Carbohydrate digestion and absorption studies in the horse

Area of Science:

• Equine Physiology
• Gastrointestinal Metabolism
• Digestive Enzyme Activity

Background:

• Soluble carbohydrate digestion and absorption are crucial for equine health.
• Lactase enzyme activity in horses is known to decrease with age.
• Understanding carbohydrate tolerance is vital for managing equine digestive disorders.

Purpose of the Study:

• To assess the digestive and absorptive capabilities of horses for soluble carbohydrates.
• To investigate the specific mechanisms of lactose digestion and absorption in horses of different ages.
• To evaluate the clinical utility of oral lactose tolerance tests in diagnosing equine gastrointestinal conditions.

Main Methods:

• Conducted oral disaccharide tolerance tests in horses.
• Administered monosaccharide tolerance tests to the same animals.
• Monitored plasma glucose levels and fecal consistency post-administration.

Main Results:

• Horses older than three years exhibited lactose intolerance, with no plasma glucose increase and soft feces.
• All age groups successfully absorbed a glucose:galactose mixture, indicating intact monosaccharide transport.
• Sucrose and maltose were rapidly hydrolyzed, with tolerance curves mirroring their constituent monosaccharides.

Conclusions:

• Adult horses demonstrate lactose intolerance primarily due to a failure to hydrolyze lactose, not impaired monosaccharide transport.
• Findings align with the developmental pattern of brush border lactase activity in the equine small intestine.
• Oral lactose tolerance testing presents potential clinical value for identifying small intestinal mucosal damage in diarrheic foals.