A blocked nose can be very uncomfortable for your dog and could signify that something is wrong. Heavy nose breathing can be associated with other sounds, such as snorting or snoring.
Some of the most common reasons why your dog might breathe heavily through their nose include:
Foreign Body
If your dog inhaled a foreign object, it could obstruct their nasal passages and cause secondary inflammation.
Infection
Viral, bacterial, and fungal infections can cause inflammation in your dog’s nasal passages.
Parasites
Parasites rarely cause breathing problems in dogs but can be the culprit sometimes. For instance, Canine nasal mites can cause sneezing, snuffling, and snorting in dogs.
Allergies
Heavy nose breathing is a sign of allergies in some dogs. Other signs accompanying it may include nasal discharge, sneezing, or snorting.
Brachycephalic Obstructive Airway Syndrome (BOAS)
Flat-faced dog breeds may suffer from BOAS, an abnormality that makes it difficult to draw air into the nasal passages.
Facial Injury
Your dog may have difficulty breathing if they injured themselves in the face. X-rays may be needed to diagnose the extent of the damage.
Given that there are many reasons why your dog could be breathing heavily, it is best to get them checked by a veterinarian, especially if they show other symptoms such as nasal discharge, snorting, or sneezing.