Do You Think I Am Over reacting?

If they cannot follow your feeding instructions, and if what they are feeding the horse will make it founder again, then I would ask them if they are going to be responsible for the vet bill, if the horse should founder under "their vet approved" alfalfa diet. I would make it clear that it is a health issue for your horse, and that they might be responsible for any problems due to their ignoring your feeding regimen. If keeping the horse at their stable is going to be detrimental to your horse, then it might be permissable to break the contract. A better way to go about it would be to hint to them to help pay the vet bill if the horse founders again, because they would be responsible if they did not follow your feeding instructions, right ? I would ask them what they think is fair - is it fair to you and the horse if they are going to cause it to founder again, is it fair for them to ignore your requests not to give it alfalfa ? They might ask you just to take your horse, if they think it might cost them money with the vet. I hope that helped.