The frog is part of the soft horn which is an important part of the hoof because it keeps the hoof elastic. However, too much additional moisture from the outside affects the frog in a negative way. If the horse was on the wet pasture and then enters its loose-box, the bacteria from the dung can easily enter the damaged horn and frog and cause the thrush. When owning a horse, check the frog regularly for thrush. Thrush is very widespread and often times the quality of the straw and the hoof care are reasons for this type of disease.There are different ways of treating thrush. There are many companies that produce frog care products. There are products that can be sprayed or brushed onto the hooves.