End of life decisions are very difficult for horse owners to make. Coming to the realization that humane euthanasia is the best course for your horse is not easy. All decisions regarding horse health and death should be made with your veterinarian.
There are many resources for a horse owner considering the humane end of life for their horse, one of which is AAEP's article "Euthanasia: Guidance for a Difficult Decision".
Some of the important questions to answer when considering euthanasia are:
To find a licensed equine veterinarian in your area to assist with end of life decisions, use these resources: