I've seen the signs. Brought my dog before and after being fixed. Got some looks before it was done. I think it's just the park trying to limit their Liability.
You watch your dog the entire time so if that sign is there not only do they not ask to see paperwork so it would be the owners risk the "recommended" comment I don't understand why that precaution is necessary because you don't leave your dog unattended... Just my opinion
No
Signs state that your dog must be fixed but not enforced.
No but recommended
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