Allergies
Although an allergy in dogs more commonly involves itchy skin, many dogs with allergies have a runny nose as well. If your dog has allergies, they can also show signs of itching, wheezing, coughing, sneezing, vomiting, and even diarrhea. The most common allergies in dogs include:
- Food
- Grass
- Ragweed
- Pollen
- Dust
- Mold
- Flea bites
Foreign Object in the Nose
It may seem strange, but it is not uncommon for dogs to get things in their noses such as sticks, rocks, grass, wood, and even bugs. This is more common in dogs with long noses like Collies, Greyhounds, Dachshunds, and Afghans. In these cases, there would only be discharge from one side of the nose. Other signs to look for include bloody discharge, pawing at the nose, and whining.
Infections
There are many infections that can cause your dog to have a runny nose. Bacterial infections, viral infections, and fungal infections are all common in dogs of any age and breed. Other signs to look for include fever, sneezing, coughing, lethargy, and a general ill appearance.
Nasal Mites
Mites are common in dogs and can cause a runny nose in any breed, age, or sex. The mites that invade your dog’s nose are about 1 millimeter long, tiny but visible to the naked eye. Mites are contagious from dog to dog and the accompanying symptoms are nosebleeds, sneezing, rubbing nose, shaking head, high-pitched breathing, white or tan specks by the nostrils, and restlessness.
Dental Disease
Many types of dental disease in your dog can cause her nose to run. Some of the most often reported are gingivitis, periodontitis, and an abscessed tooth. To check your dog for dental disease, lift up her top lip and look at her teeth and gums. Open her mouth and check every tooth and look for redness and swelling.
Nasal Cancer
There are several types of nasal cancer that can cause a runny nose. Some of these include squamous cell carcinoma, osteosarcoma, adenocarcinoma, chondrosarcoma, and fibrosarcoma. Some other symptoms that occur with nasal cancer are a bloody nose, mucus or pus in the nose, breathing difficulty, seizures, pain, facial deformity, and discharge from eyes.