Unless there was some blatant disregard and previous violence from the dog, you probably can't "sue the fooker".

Call animal services and report the incident. Hopefully there was some type of witness so it isn't one persons word vs another. I would start documenting the patio, the fence the dog jumped, etc.. to get to the other dog. You should also start documenting any known other aggressive behavior by the dog, interviewing neighbors etc.

You need to build a case, unless there are pics/vid of the attack happening. You can't just say "that dog did it".

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We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.