There are places structured to help horse owners recover from natural disasters. Here is a list of those I trust.
American Association of Equine Practitioners Foundation Equine Disaster Relief Fund.
If you wish to offer assistance with supplies or other resources, please email Keith Kleine at kkleine@aaep.org, and you will be contacted with further instructions.
United States Equestrian Federation Equine Disaster Relief Fund
Formed to help ensure the safety and well-being of horses during trying times, this organization aids horses across all breeds in disaster-related situations.