According to VetInfo, a trusted resource for veterinary medicine, wheezing and a runny nose often occur as the result of an allergy. An allergy is an overreaction of the immune system to a non-pathogenic agent. Allergies can occur at any time during a dog's life, and some dogs exhibit symptoms, such as a runny nose, in the early spring or fall.
VetInfo notes that seasonal symptoms resolve themselves during other parts of the year. Besides seasonal allergies, dogs can display wheezing, coughing or a runny nose when they are exposed to dust, mold or cleaning chemicals. Allergies are typically treated by the removal of allergy-producing substances from a dog's surroundings or by treating the dog with an anti-allergy medicine.
According to VCA Animal Hospitals, which are represented in 42 states and four Canadian provinces, the most prevalent symptom of an allergy in a dog is itching, followed by allergies of the respiratory tract and digestive system. Any suspected allergic response should be checked by a veterinarian. Allergies are common in all dog breeds and appear after a dog is 6 months old. Most dogs are affected by some type of allergy by the time they are around 2 years old.