As with humans, there are several different causes for dog nasal congestion; understanding the underlying cause is the key to effective treatment. PetMD suggests using a humidifier in the room where the dog spends most of his time to help loosen mucus and allow it to drain.
If the discharge is thick, the dog is likely suffering from a bacterial infection and should go to the veterinarian. In most cases, vets prescribe antibiotics for this condition. The doctor also examines the dog for potential growths in the passageways that could be causing the congestion, according to PetMD.
VetInfo says that pets that spend large amounts of time outdoors sometimes breathe a fungal infection into their respiratory tract. Fungal spores thrive in the warm, moist environment of the dog's nose and sinus passages. The vet usually prescribes an antifungal medication to apply to the pet's nose to stop the problem.
According to VetInfo, some pets have nasal congestion due to allergies. In order to help a pet, owners need to eliminate the allergen from the home. Installation of an air purifier helps to trap allergies and allow the dog to breathe easier. If the dog's allergen is located outside the home, it is helpful to limit outdoor time or at least keep it away from the source of the problem.