Your dog should be fine in most cases, but there are some risks. Rats can carry diseases (like leptospirosis, or bacterial infections) and may also have been exposed to rat poison. If your dog got bitten or had direct contact with the rat’s blood/saliva, there is some risk of infection. Immediately wash your dog’s mouth and any wound with clean water and mild antiseptic (if there is a bite). Check your dog’s vaccination status (especially rabies and leptospirosis). If not up to date, contact your vet urgently.Monitor for signs like fever, loss of appetite, vomiting, yellow eyes, blood in urine, or unusual behavior.Visit a veterinarian within the next 24 hours for a thorough check-up

Rats can carry so may pathogens in them and they are the main reason for secondary rat kill poisoning. Get your dog checked to make sure he is completely fine.