How can I keep cats and dogs off my yard?

If you live in an area that has an animal control by-law then call your municipality to have the animals picked up. Take a photo of the offending dogs so that you have some proof and the catcher can locate the dogs. If you know whose dog it is then call the owner and discuss the problem with them. Hopefully they will understand your frustration.

All I know ,is to fence it.

How inconsiderate! Put up a sign. Until they heed your displeasure, try these remedies:

https://www.rd.com/advice/pets/5-ways-to-keep-cats-and-dogs-away-from-your-garden/

https://www.thespruce.com/use-dog-repellents-2132575

https://www.thespruce.com/cat-repellents-to-keep-cats-out-of-your-yard-2132573

https://www.marthastewart.com/913526/how-keep-cats-and-dogs-out-your-garden

Before you let your granddaughter out to play, do a walk through to pick up any poop that might be left behind.

Thats very inconsiderate and irresponsible, I hope you find a solution to this frustration situation. I don’t understand this or people in our rural gated community throwing or disposing bottles and cans in the roadside.

Try spreading an obnoxious smelling product, such as moth balls. Soak old rags in ammonia to spread out when you expect a visit. And yes, put up a sign for owners and notify owners if you know who they are.