Sounds like a good time to move, if you think you and the neighbor are going to escalate things over the next few months.
I represent Employers, but I can recommend Worker Attorneys in So Cal if you ask.
Lots of incidents, little suggesting any measure of proof. Make peace with your neighbors, or move. It's what most folks do when they are not getting along well and sharing regular picnics.
Your post contains no evidence of "witness statements" or "racism" and only a suspicion of animal cruelty. As your local police officer appears to be worthless, document all instances of the rottweiler running loose with a camera while you wait for the toxicology report.
Note that, even if you have evidence of poisoning, you will not have any proof of who did it.
The foregoing is for general information purposes and does not establish an attorney-client relationship.