1 24-hour emergency animal hospital in Ontario — open now, no appointment needed
If your pet needs emergency care in Ontario, California, the hospitals listed above are open 24 hours a day, 7 days a week including holidays. No appointment is required for emergency cases — walk in any time. For life-threatening situations, call ahead so staff can prepare. All listed hospitals offer emergency triage, critical care, and after-hours veterinary services.
Get priority placement with a Featured Listing. Starting at $149/month — no contract required.
Claim Featured Listing →When your pet needs emergency care in Ontario, CA, time is critical. VetUSA lists every 24-hour emergency animal hospital in Ontario — all open around the clock with no appointment needed. Emergency services available in Ontario include trauma care, critical care, surgery, advanced diagnostics, imaging, and overnight hospitalization. Whether your dog was injured, your cat is in distress, or you face any urgent pet health crisis, Ontario emergency vets are ready to act immediately, 24 hours a day, 7 days a week, 365 days a year. All hospitals listed serve Ontario and surrounding areas in California. Find the nearest 24-hour emergency animal hospital in Ontario and get your pet seen right now — no referral, no appointment, no wait.