Horse Toad: Environmental Influence and Genetic Predisposition

Introduction: Why do some horses develop canker?

Canker (or thrush in English, though canker is often used specifically for this condition) is a chronic hoof disease that does not affect all horses equally. While humidity is often blamed, the reality is more complex: some horses develop canker despite impeccable hygiene conditions, while others remain unaffected in very humid environments.

This disparity is explained by the interaction between environmental factors and individual predispositions. Understanding these mechanisms allows for adapting prevention and treatment to each horse. For an overview of the disease, consult our FAQ on canker myths and realities.

Environmental factors: humidity and beyond

1. Humidity: the main triggering factor

Excessive humidity remains the most critical environmental factor. It causes tissue maceration, promotes the proliferation of anaerobic bacteria (Fusobacterium, Porphyromonas, Treponema), alters the skin barrier, and modifies the pH of the frog.

Problematic humidity sources: poorly drained stalls, muddy paddocks, rainy seasons without dry shelter, frequent washing without complete drying.

2. Lack of hygiene and maintenance

The accumulation of manure and urine creates an acidic and corrosive environment for the horn. Insufficient cleaning allows for the stagnation of material and bacterial growth. Irregular trimming encourages deep crevices where moisture stagnates.

3. Mechanical and structural factors

Hoof conformation influences risk: atrophied frog (not touching the ground), contracted heels (deep and narrow crevices), flat feet, ill-fitting shoeing (plate shoe trapping moisture), and lack of exercise which reduces blood circulation.

4. Climatic and seasonal factors

Canker shows marked seasonality: autumn and winter are the highest risk seasons, while dry summer is generally a period of remission. Regions with high rainfall (oceanic climate) are more exposed.

Individual predispositions: why some horses are more vulnerable

1. Breed predisposition

High-risk breeds: draft horses (Shire, Clydesdale, Percheron, Ardennais), Friesians (a particularly sensitive breed with possible specific genetic predisposition), feathered breeds (Gypsy Cob, Tinker, Irish Cob).

Less affected breeds: Thoroughbred, Arabian (drier hooves, less feathering), mountain breeds adapted to rocky terrain.

Important: Breed is not destiny. Many draft horses live without ever developing canker thanks to appropriate management.

2. Genetic and family predisposition

Some breeders observe that offspring of horses that have had canker are at higher risk. Horn quality, hoof conformation, and immune response are genetically determined. Veterinary studies are currently exploring genetic markers associated with canker susceptibility, particularly in Friesians.

3. Immune and metabolic factors

General health plays a crucial role: Cushing's (PPID) causes immunosuppression and slowed healing, equine metabolic syndrome leads to chronic inflammation, advanced age reduces immunity, chronic stress, and nutritional deficiencies (zinc, selenium, vitamins A and E) weaken defenses.

4. Hoof microbiome

Emerging concept: each horse has a unique hoof microbiome. A healthy microbiome protects against pathogens. Dysbiosis (imbalance) promotes pathogenic bacteria. The environment directly influences this microbial balance.

5. History and recurrences

A horse that has previously had canker is more likely to recur due to residual tissue damage, a persistent unbalanced microbiome, and weak areas that favor reinfections.

The environment-predisposition interaction: the multifactorial model

Canker results from a combination of causes. A non-predisposed horse in a humid environment will develop less severe canker and heal faster. A predisposed horse in a suitable environment may still be affected. The highest risk situation is the combination of a predisposed horse + unfavorable environment: rapid and severe development, long treatment, almost systematic recurrences.

Practical implications for prevention and treatment

For all horses:

• Rigorous hygiene: Daily cleaning, clean and dry stall
• Adapted environment: Well-drained paddock, accessible dry shelter
• Regular trimming: Maintaining a functional frog
• Balanced nutrition: Supporting horn quality and immunity

For at-risk horses (draft breeds, history of canker, immunosuppression):

• Active prevention: Regular application of OZONE SOIN SABOT 1-2 times a week on the frog, especially during the wet season
• Feathering management: Regular cleaning, clipping if necessary
• Immune support: Optimal nutrition, stress management, treatment of underlying diseases
• Early intervention: Treat at the first signs with OZONE SOIN INTENSIF

For horses with recurring canker:

• Veterinary check-up: Look for underlying diseases (Cushing's, EMS)
• Radical environmental modification: Change of bedding, improved drainage
• Prolonged treatment: Continue several weeks after apparent healing
• Therapeutic shoeing: Plate shoe with drainage holes, breathable pads

The role of natural ozone care

Ozonotherapy perfectly adapts to this multifactorial approach:

For prevention (at-risk horses):

OZONE SOIN SABOT creates a protective barrier against moisture, maintains a healthy and oxygenated environment, and prevents bacterial proliferation.

For treatment (declared canker):

OZONE SOIN INTENSIF provides daily treatment (twice a day) of lesions with a non-resistant antibacterial action and stimulated healing. The Ozone Bagging Device is essential to reach deep infections via the gaseous form. Consult our complete canker care protocol or our article on removing degraded keratin.

Benefits for predisposed horses:

• Natural treatment with no side effects
• Effective even on resistant bacterial strains
• Long-term use without risk
• Compatible with all veterinary treatments

Conclusion: a personalized approach

Equine canker results from a complex interaction between environmental factors and individual predispositions. Understanding this dynamic allows for adopting a strategy adapted to each horse:

• Assess individual risk: Breed, history, health status, conformation
• Optimize the environment: Adapt living conditions to the risk level
• Actively prevent: Preventive care for at-risk horses
• Treat effectively: Natural ozone solutions for lasting healing
• Monitor long-term: Continuous vigilance to prevent recurrences

Every horse is unique. Adapt your strategy to its specific needs to offer it the best conditions for hoof health!