My very dear one,
I have seen the photo of the horse. It’s very sad and unfortunate this happened, but at the same time, I am very, very happy about all the work you do caring for the animals.
I checked and it comes out very good if one of the geshes from your local center could recite Most Secret Hayagriva mantra on some healing substances / ointment or butter that can be applied to the lesions. If possible, the mantras should be recited over some days and then the ointment which is blessed by the mantra can be applied to the wounds.
With love and prayers ...