Vet at FirstVet answers:
Several things can result in a stuffed nose and irritated throat. The most common cause is a viral airway infection.
Just like when we get a cold, dogs should also take it easy. Clean its nostrils so they are free from discharge and keep an eye on your dog’s general condition. You should seek veterinary care if your dog seems very tired, develops a fever (rectal temperature over 39°C), does not want to eat, or if the snot/discharge becomes thick and yellow or your dog seems to have trouble breathing.
Allergies, dental disease, foreign bodies, and tumours in the nasal passages can also result in the aforementioned symptoms.