And their role in equine gut function

Text: Ilsemarie Greyvenstein

Equine gastrointestinal parasites, particularly Strongyles, have long been studied for their pathogenic (disease-causing) effects. However, some of the new research suggests that certain enzymes produced by these parasites may play a role in modulating gut function in a beneficial way. This article explores the biochemical interactions between parasite-derived enzymes and equine digestive physiology, with a focus on their contributions to nutrient metabolism, microbial balance, and overall gut health.

Strongyles and their gastrointestinal presence

Strongyles, especially the small strongyles, inhabit the large intestine, progressing through several developmental stages there. Traditionally viewed only as harmful, their close contact with gut tissues and the resident microbiota has prompted renewed scientific interest in how their secretions might influence digestion.

Enzymes at work

Recent studies indicate that strongyles secrete proteases (also known as peptidases or proteinases). These are enzymes that break down proteins into smaller peptides and amino acids. In horses, these same enzyme types are essential to nutrient absorption and gut function.

Within the equine digestive tract, proteases can:

Proteases contribute to several physiological processes in the equine gastrointestinal tract:

• Protein breakdown: Proteases hydrolyse dietary proteins into peptides and amino acids, which can then be absorbed into the bloodstream through the small intestine.
• Microbial interactions: Some gut bacteria produce proteases that aid in protein metabolism, influencing microbial balance and fermentation efficiency, through supplying protein fragments that bacteria use as energy sources.
• Immune modulation: Proteases can regulate immune responses by processing signalling molecules and degrading invading proteins.
• Parasite-host interaction: Certain equine parasites, including strongyles, secrete proteases that may interact with gut tissues, potentially influencing nutrient absorption and immune responses.

Scientific interest in proteases has grown because these enzymes bridge nutrition, microbiology, and parasitology. Understanding their effects could refine approaches to:

• Targeted deworming guided by faecal worm-egg counts.
• Nutritional plans that optimise protein metabolism.
• Microbiome-based strategies for supporting gut stability.

Other parasites and their enzymatic roles

While strongyles are the best-studied, several other equine parasites also produce biologically active enzymes:

• Tapeworms (Anoplocephala spp.) may secrete compounds that alter carbohydrate metabolism and microbial fermentation patterns.
• Ascarids (Parascaris equorum) release proteolytic enzymes that impact protein digestion and absorption in the small intestine.
• Trematodes (Gastrodiscus spp.)have been shown to interact enzymatically with gut mucosa, potentially influencing nutrient uptake and immune responses.

Recognising these patterns helps researchers design parasite-control strategies that safeguard, rather than disrupt, gut homeostasis.

The science behind the synergy

Parasites coexist with an intricate microbial ecosystem. Their enzymatic secretions can shift bacterial populations, sometimes impairing fibre fermentation, but occasionally stimulating microbial diversity and immune tolerance.

Implications for equine health and management

While parasitic infections will always carry risk, these findings remind us that not every parasite-host interaction is purely destructive. Future studies should aim to:

• Identify specific parasite enzymes and their biochemical pathways.
• Quantify their effects on nutrient absorption and microbial equilibrium.
• Design deworming programmes that protect the wider gut ecosystem.

If science can better define which enzymatic processes are harmful and which might be neutral or even beneficial, equine parasite control could evolve from eradication to ecological management, supporting both horse and microbiome health.

Conclusion

Parasite-derived enzymes represent a fascinating aspect of equine parasitology, with potential implications for gut function and health. Continued research into these biochemical interactions will enhance our understanding of equine digestive physiology and inform sustainable parasite management practices.