I find it hard to understand why some will forfeit their rights for the convenience of irresponsible folks. Your property is yours and as long as you do not violate any ordnance or the rights of others, what you do on your property is you business. If you leave toxic material where a neighbor's dog, or any other animal for that matter, can ingest it, you have done nothing wrong. Unless the item is labeled for proper storage/disposal. If you put laxatives out and the neighbors dog eats it then squirts in their house or in your yard it probably won't solve the problem and may cause unintended harm to the dog.
I have always had dogs and have from time to time let them run. Generally speaking I am not bothered by the occasional dog visiting my property. Without exception if my dogs were indicated as a problem or even a nuisance, I would restrict them to my property. I have spent time and money to ensure my dogs remained on my property. I expect the same from any of my neighbors. For someone to expect you to allow their animal unrestricted access to your property is a form of bullying in my opinion. Owning animals requires a level of responsibility. You can not be held responsible for the irresponsibility of others.
Put up the fence and a security or game camera may not be a bad idea either.
