some suggestions:
1. make sure a vet has seen all of you animals and has determined that they are ok.
2. i assume that the human society/animal shelter would be the one to take action if the horses were to be removed. you may want to talk to them and you may even want to show them current documents from your vet. ANYWAY, WHAT DID THE ANIMAL SHELTER PERSON SAY...HE/SHE would be the expert? And 100 bales of hay???? come on, give me a break.
3. neighbors...not awhole lot you can do unless they are on your property.
4. get reports of police complaints
5. give vet reports to sheriffs office. also, is it the sheriff who is talking to you or a deputy?????? you may want to talk to the sheriff directly if it is just a deputy.
6. make sure your horses don't get loose, even for one moment.
7. as a backup plan, you probably need to see an attorney and find out the process is for taking your animals.

