My dog has a runny nose, what may this depend on?

Anything that irritates the mucous membranes in the nose can result in a runny nose. A common cause is an airway infection, often viral in nature. It is important to let your dog rest, dry its nostrils and be aware of your dog’s demeanour. If your dog becomes very tired, develops a fever (a rectal temperature over 39 °C), loses its appetite or if the nasal discharge becomes thick and yellow it may be wise to consult a veterinarian. Other conditions that result in a snotty nose are for example  allergies, infected teeth or a foreign body in the nose (such as a grass seed).