Excessive sneezing in dogs is usually caused by allergies, infections, foreign bodies, or tumors. They are all very different and present predictable signs and patterns.
Allergies: Allergies are usually seasonal and the most common ones are in response to pollen grains and other plant fibers. Tree pollens are most abundant in the late spring and early summer, grass pollen is usually a mid-summer ordeal, while the weeds and other plants generally liberate their pollen in the fall. Each type is present for only two to four weeks. Since a dog is usually only allergic to one of these, sneezing is limited to a certain period. Combine the sneezing with some watering of the eyes, chewing on the feet, and scratching on his sides, and that is about all you need for a diagnosis. There are a few animals that are allergic to things that are inhaled such as rug fibers or cigarette smoke. In these cases, it is fairly easy to recognize the relationship between the sneezing and the presence of these types of allergens.
With any allergy-induced sneezing it will be bilateral, which means that it affects both the right and left nasal passageways. There will be a discharge from both nostrils, however, there will rarely be any blood or pus-like material in this discharge.
Patients with allergies suffer but generally show no other signs. They eat, drink, and remain as active as they always were. Infections that cause sneezing are probably more common in humans than in dogs. Our canine friends have nothing comparable to our common cold that affects their nasal passages. Their most common respiratory infection is Kennel Cough Syndrome, but it affects the throat and windpipe, resulting in a hacking cough, that is without sneezing.
Infections: Infections that do induce sneezing in the dog are usually more serious. It may be an infection from a tooth or its root that protrudes upward and drains into the nose. There are infections that occur on membranes within the nose or sinuses, but with rare exceptions, they are just pathological organisms that happen to end up there and are not limited to this area of the body (as is the cold virus in humans). Dogs that suffer from a bacterial, viral, or fungal infection of the nose can have the condition at any time of the year. In most cases they turn into long term, chronic conditions. There is almost always a bloody or pus-like discharge from the nose and it may affect one side only or both sides.
Foreign Bodies: Foreign bodies, a picturesque term referring to an inanimate object that has gained access to the dog's body, can cause some horrendous sneezing fits in the dog. Finding a foreign body in the nose of a dog is not a rare occurrence. It always causes sneezing and there is usually some blood in the nasal discharge. As would be expected, this discharge only comes from the injured side of the nose. Typically, your veterinarian will remove the foreign body and administer an anti-inflammatory medication and antibiotic.
Tumors: In the older dog, usually eight years of age or older, we may encounter another cause of sneezing ? a tumor. They are not very common. Dogs with an intranasal tumor usually exhibit a bloody discharge from only one side and the sneezing, unlike the animal with a foreign body, starts out as only an occasional occurrence. Over a period of several weeks or months it becomes more frequent. It is a slow process, causing no rapid changes within the area. These tumors are typically malignant and therefore difficult to treat. Surgery and chemotherapy are always available, but surgical intervention in this area of the body is extremely difficult.
Unlike people, if your dog ever has a bloody nose it is always cause to see the veterinarian. And if sneezing is causing discomfort for the animal or concern for you, a visit to the veterinarian is also recommended. Chances are that it probably won't be anything serious but, like so many conditions, the sooner treatment is initiated, the easier it is to eliminate the problem.