Dog Cold Symptom: Causes Based on Color of Nasal Discharge

Symptoms of dog sneezing and nasal discharge indicate some type of medical problem in the nasal cavity. As indicated on the previous page, symptoms can indicate a wide range of problems including infections, foreign objects, injury or tumors (neoplasia).

Clinical signs or symptoms, such as the symptom itself (sneezing, discharge, reverse sneezing or harsh or whistling sounds) can provide some indication as to the cause (see first table below). The color of the nasal discharge color (see bottom table below) can also provide clues as to the cause.

Anatomy and Dog Upper Respiratory Problems

A veterinarian will start an examination by using the clinical signs to locate the part of the respiratory tract that is causing the problem. The table below matches typical dog cold symptoms to the dog's anatomy.

Dog Cold Symptom and Area of Nasal Anatomy
Symptom Location of Dog Nasal Problem


Dog sneezing or that has nasal discharge
  • Nose
  • Nasal Cavity
  • Nasal Sinus


Reverse dog sneezing, loud dog snoring when sleeping (refereed to as stertor)
  •  Narrowed breathing passages
  • Problem with the passage that connects the nasal cavity to the top of the throat (nasopharynx)


Whistling or harsh sounds when the dog is breathing (stridor)

  • Problem in the larynx (he air passage between the lower pharynx and the trachea)


Dog Nose Anatomy
Source: The picture of dog nasal anatomy shown above is reprinted with permission by the copyright owner, Hill's Pet Nutrition, from the Atlas of Veterinary Clinical Anatomy. These illustrations should not be downloaded, printed or copied except for personal, non-commercial use.

This is a complicated area of a dog's body, making it difficult to quickly identify the problem based on symptoms alone.

Nasal Discharge Color and Related Causes For Dog Congestion

Dog Cold Symptom - Nasal Discharge Color
Dog Nasal Discharge Color Possible Cause when accompanied by dog sneezing



Clear (serous)
  • Canine Allergies: sneezing is usually intermittent. Other symptoms including itching, scratching, dog hair loss, licking of the paws, and face rubbing. Treated by identifying and removing the cause.

  • Dog Nasal Mites: The mites cause clear discharge from both nostrils. Treated with prescription medications.



Cloudy,  Gray or Green: may contain pus or mucus (gel like)
  •  Foreign object in the nose (such as weeds or grass): results in pawing at the nose and sneezing which becomes more intermittent over time. Discharge tends to be from one nostril.

  • Infection in the roots of the upper teeth causing an abscess: discharge is usually from one nostril. As disease worsens discharge can spread to both nostrils.

  • Dog nose cancer (nasal cancer) - blood may be present in the discharge (note that if dog sneezing is violent, this can cause some blood to appear without the presence of cancer or infection). Dog nasal tumors are difficult to surgically eliminate. If left untreated, tumor growth can result in seizures or changes in canine behavior.

  •  Fungal infection: blood may be present in the nasal discharge. Caused by Aspergillus. Treated with fungal medications.

References for Dog Worms Types

IVIS – International Veterinary Information Service
Atkins, Clarke E. DVM, Canine Heartworm Disease: Prevention and Treatment

Heartworm Disease in Dogs; Venco, Luigi

U.S. Food and Drug Administration

Researched by: Jeff Grill

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SNEEZING AND NASAL CONGESTION