Q. Do dog allergies cause nasal congestion
DESTINI R. HOLLOWAY, DVM
A. Yes allergies in dogs can cause nasal congestion and also nasal discharge. But so can a number of other things which include: fungal infections, foreign bodies in the nose, parasites (in particular Pneumonyssoides caninum), etc.
If your pets has congestion and also green or yellow discharge then a secondary bacterial infection is present and she needs antibiotics to treat.
You can try an antihistamine to help alleviate symptoms, I recommend Benadryl given @ a dosage of 1mg/lb to start. If no improvement of the congestion within 12-24 hrs then a vet visit is needed for a good visual of the nares, a good listen of the heart and potentially stronger medications.