Thrush, a common hoof problem in horses, is a bacterial or fungal infection that affects the centre and grooves of the frog. A Dutch study conducted in 2017 found that 45% of randomly selected horses were affected by thrush, indicating its widespread occurrence.
The primary cause of thrush is prolonged exposure to wet footing, which makes horses susceptible to infection. Environmental factors play a significant role, particularly in muddy outdoor conditions. Kyle David, an Ontario-based farrier, emphasizes that horses living in muddy environments are particularly prone to thrush due to inadequate air circulation in their feet and prolonged exposure to mud and manure.
Even horses kept in stalls can develop thrush, especially if the stalls are damp or not cleaned regularly. It is worth noting that even well-maintained barns can harbour bacteria responsible for thrush. Standing in a stall for extended periods or in damp bedding or manure can also trigger thrush, with the hind feet being the most susceptible.
Conformation can also contribute to a horse's likelihood of developing thrush. Horses with long heels and deep, narrow frog sulci, combined with poor stabling conditions, are more prone to the infection.
Identifying thrush is relatively straightforward. The affected areas of the frog may exhibit a black, foul-smelling discharge. The heel can become soft and squishy, and the horse may react or flinch when pressure is applied to the infected areas.
Treatment of thrush begins with the removal of dead tissue from the hoof, a task that should be performed by a farrier or veterinarian. Kyle David explains that removing necrotic tissue allows the hoof to dry out and prevents the further spread of bacteria. Once the infected tissue is removed, the farrier will clean the center sulcus and back of the frog.
Owners can also contribute to the healing and prevention of thrush. Various products are available on the market, such as Thrush Buster or Kopertox, as well as iodine-based hoof packing. Alternatively, a homemade solution of vinegar and copper sulfate in a spray bottle can be applied several times a week. Vinegar acts as a drying agent, penetrating the affected areas effectively. However, it is crucial to avoid using bleach, as it can harm both beneficial and harmful enzymes and potentially cause discomfort to the horse.
Neglecting thrush or leaving it untreated for an extended period can lead to the development of white line disease. This bacterial infection attacks the white-line membrane that connects the sensitive sole to the hoof wall. In severe cases, the farrier may need to remove a portion of the hoof to expose it to air and eliminate bacteria. If thrush progresses unchecked, it can also result in canker, a painful condition where proud flesh must be surgically removed.
To prevent thrush, it is essential to maintain a dry and clean environment for horses. Additionally, ensuring horses are up-to-date on their tetanus vaccine is crucial. With proper treatment, most cases of thrush can be resolved within 7-14 days.