Thrush is a common hoof issue in horses, ponies, donkeys, and mules. While we don’t know exactly what causes this problem, anaerobic (doesn’t like oxygen) bacteria are thought to play a key role. In fact, Fusobacterium necrophorum, which is present in animal feces and most soils, has been associated with the condition. Some fungi have also been associated with equine thrush.

In this video, Sina Parsaye, DVM, of Colorado, talks about identifying and treating thrush in horses.

(Editor’s note: The content of this video is the expert’s approach to the topic. Please consult with your practitioner if you have questions.)

Click on the above player to watch the video.

What It Is

Many people think thrush is only found in horses kept in moist, unsanitary conditions (i.e., horses standing in wet, mucky stalls or pens). However, thrush can occur in horses living in pristine environmental conditions.

Thrush is generally found in or around the triangle-shaped frog of the hoof. It often takes up residence in the collateral sulci (the grooves adjacent to and in the middle of the frog) and/or in the central sulcus (the cleft between the heels).

Clinical Signs

There are some distinctive clinical signs if your horse has thrush. They include:

  • foul-smelling foot;
  • watery, oily, greasy discharge (often black in color);
  • tenderness in the frog area;
  • deepening of the heel bulbs or sulci of the foot;
  • lameness if the infection gets into sensitive structures of the foot.

What to Do

Parsaye said if you notice a distinctive noxious odor when picking out your horse’s feet, be alert for thrush.

The foot (or feet) need to be cleaned out and an over-the-counter thrush medication applied.

Continue to pick out and treat your horse’s feet regularly and provide dry bedding or footing. This helps oxygen get into the hoof crevices so the bacteria are not able to grow.

If the thrush gets worse or doesn’t go away even though you are treating it, call your veterinarian