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Also Known As

Foot infection


Thrush is an infection of the frog in the foot of the horse and is usually caused by the anaerobic organism Fusobacterium necrophorum. The frog has two distinct layers, the external skin, known as the horn tissue, and the corresponding vascular layer of tissue, called the sensitive corium.

Beneath the inner sensitive layer is a pad-like shock absorber, called the deep digital cushion, that reduces concussion for the horse's hoof and the entire limb. A hoof that is infected with thrush will exhibit soreness and contain black, pus-like liquid. Some bleeding may occur, and a strong, foul odor is emitted by the infected area.


  • Tenderness and pain in the foot
  • Black, pus-like fluid
  • Poor growth and degeneration of the horn
  • Bleeding
  • A foul odor


Thrush is caused by anaerobic bacteria and usually affects horses that live in wet conditions. Stalls and pastures with an environment contaminated by urine and acidic manure are breeding grounds for the thrush bacteria. The infection is accelerated by lack of proper hoof hygiene.


Proper care of the horse's hoofs is the best prevention of thrush. Horses that are kept in stalls with clean, dry shavings and have their feet thoroughly picked on a regular basis very seldom develop thrush.


Treatment of thrush is best done by a farrier or veterinarian, although commercial treatments are available to owners and handlers to treat the disease. The horse should be moved to a clean, dry area, and antiseptic foot wash used to clean the hoofs. The hoofs, particularly the frog area, should be thoroughly cleaned and trimmed. This will help aerate the frog area, and the effectiveness of medication applied to the affected areas will be maximized.

Once cleaned and medicated, the hoofs should heal within six to seven days if the horse is kept in clean, dry conditions.

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EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.