Quick answer
Seek medical care and appropriate animal/public-health reporting; liability rules vary.
Do now
Identify the animal and owner if safely possible, vaccination information through proper channels, witnesses, location, and injuries. Preserve photos and treatment records. Ask a local lawyer about the applicable legal theory and insurance.
Watch for
Do not approach an unsafe animal to collect evidence. NJ, NY, and DC do not have one interchangeable dog-injury rule, and a bite and a non-bite collision may raise different questions.
Official sources
NJ Courts — Statute of Limitations FAQ, NY Courts — Statute of Limitations Timetable, DC Code § 12-301.
