To find a vet open on a Sunday, research the hours of surrounding clinics. To do so, call the clinic or go to the clinic's website. There are also websites to find clinics if no known clinics exist.
Veterinarians.com is one website that lists vet clinics in any area, along with the surrounding areas. The site gives the clinics' hours, phone numbers and locations. Most vet clinics are closed on Sundays, but there are emergency vets that can be contacted if needed. LocalVets.com has a list of emergency vets in multiple areas that can be found with a ZIP code or city name.