From: Equestrian and Horse | Horse Ailments
Equine Thrush In Horses
This is a bacterial infection which causes the soft tissues of the frog to degenerate. It is in the central and lateral grooves of the frog which are most affected and as the bacteria rot away the frog a very distinctive unpleasant odour will be present often with a black discharge.
Horses It Affects
Any horse kept in muddy, damp, wet or unhygienic conditions. It can affect both fore and hind legs.
Symptoms
To start off with the horse may well be sound but if the infection is left untreated the infection will soon spread to deeper underlying tissues within the hoof and the horse will soon become lame. The horse will show pain when pressure on the frog is applied. Thrush is known for the foul smelling black discharge it gives off.
Treatment
This will need to be done by your veterinarian who will pare away the damaged soft tissues of the frog and a antibacterial solution will be applied quite often along with antibiotics to assist.
The frog will need to be kept clean and dry to allow healing to take place so the hoof is often bandaged to allow this to happen.
Prevention
Regular maintenance of hoof care and hygiene are essential to help prevent thrush from occurring.