Pets and people sneeze for two reasons. Either the membranes that line their nose are inflamed or a foreign object of some sort is present in the nostrils.
Nasal membranes become inflamed either because the pet was exposed to a chemical irritant or it has contracted a respiratory tract infection.
By far, most of the sneezing pets that I see have contracted upper respiratory tract infections. Some times the only symptom of the infection is sneezing. In people, we would call it a cold. Pet colds are caused by airborne virus and bacteria. The two most common cold viruses of dogs are the Parainfluenza virus and Type-2 Adenovirus. Both are highly infectious and are passed by sneezes from other sick dogs or from dogs that silently carry the infection. It is very common for the owners of sneezing pets to tell me that their "baby" was boarded, groomed or exposed to neighboring pets or a doggy park within the past two week. Pets that were recently obtained from animal shelters are also more likely to have these infections.
Very young and very old pets are more at risk. This is because the immune system of young animals is not fully developed. Older pets often have some age-related changes of the nasal membranes that make infections worse.
Bacteria can also cause sneezing. Both cats and dogs are susceptible to bacterial upper respiratory tract infections caused by Pasteurella, Bordetella, Streptococci and pseudomonad bacteria. Bordatella and Adeno-2 are two of the causes of kennel cough. Many of these bacteria are not particular about whose nose or eyes they irritate and can cause similar problems in you. Some pets silently carry these bacteria and virus in their system. Although they appear perfectly healthy they can spread the infections to all the animals that they contact. It is quite common for two or more organisms to be involved simultaneously in respiratory tract infections.
In cats, the two most common causes of sneezing are the rhinotracheitis virus (Herpes-1) and Calicivirus. Although sneezing may be the only sign of infection, most cats also have conjunctivitis and run a low-grade fever. Again, many healthy pets harbor these viruses and spread them. The rhinotracheitis virus is the cause of over two-thirds of the sneezing I see in cats. The incubation period after exposure is 2-6 days. Cats that harbor this virus are often infected for life. It is much like the cold sore virus of people in that stress of any sort causes these cats to resume shedding the virus. It is the bane of catteries and animal shelters. The next two most common causes of sneezing in cats are the organisms Chlamydia psittaci and mycoplasma. Both these organisms cause nasal irritation and conjunctivitis. Sneezing begins 5-10 days after exposure.
Causes of Sneezing
Certain breeds of dogs and cats have compressed nasal passages due to their conformation. Persian cats and other cats with a flat face are more likely to sneeze due to infection or irritating products. Any of the dogs breed that snore (Pekingese, pugs, bulldogs, Lhasa Apsos, Shia Tzu etc.) share this problem.
In both dogs and cats the third upper premolar tooth has roots that penetrate close to the nasal passages. If this tooth or the ones adjacent to it becomes infected, sneezing and nasal drainage are common signs.
It is quite common for pets to poke their nose into grassy or dusty areas and come away with a small portion of grass or seedpod lodges in their nostril. Any nasal drainage of this sort will be confined to the side that has the object. Most pets eventually sneeze these objects out but some of them must be physically removed.
Older dogs and cat are subject to nasal polyps, tumors and degenerative changes in their airways. . As with foreign objects, the problem is usually confined to one nostril.
Although most allergies in pets are exhibited as itching, some pets sneeze due to pollens and mold in the air.
The same household products that cause you to sneeze can cause you pet to sneeze. The most common culprit in cats is dusty cat litter that contains small spicules of silica. Perfumes, cigarette smoke, household cleaners, fiberglass, bug spray and deodorants are only a few of the products that can cause your pet to sneeze.
We try to prevent upper respiratory tract infections in dogs and cats with yearly vaccinations against the organisms involved.There is an old saw among veterinarians that sneezing left untreated lasts a full two weeks; but if properly treated it passes in fourteen days. This is not always so. Sometimes sneezing the only the first sign of a respiratory tract infection. One of the best ways to tell if the problem is minor or more major is to take the pet's temperature with a rectal thermometer. Don't bother to see if its nose is warm or cold-that never works. The normal temperature of a cat or dog is about 102.5F. If the temperature is over 103.5 it might indicate that the problem will develop into a more serious respiratory tract infection. In that case, antibiotics and a visit to a veterinarian are probably indicated. Otherwise, rest, good nutrition, and medicated nose drops containing 0.25% ephedrine sulfate will probably be sufficient. If the nostrils become raw and inflamed I dispense a bland ophthalmic ointment and have the owners clean the nose frequently with warm wet pledgets of cotton.
When Rhinotracheitis virus of cats is the cause of the sneezing it is difficult to cure the cat. When this disease attacks kitten it sometimes causes irreversible changes in linings of the nose that do not go away. As mentioned earlier, this virus often persists in cats throughout their life. Low stress, good nutrition, vitamin A and antibiotics to combat secondary bacterial infections often cause the disease to disappear or go into remission. If this treatment does not cure the problem in a few weeks, I put the cat on trifluridine (Viroptic) or idoxuridine ophthalmic drops administered in the nose four times a day. Steam administration or taking the cat into a hot shower helps cleanse the nose of exudates and open the nasal passages. I have not found acyclovir helpful in these cases. A similar drug, gancyclovir may be more effective. Because cats appetites are so reliant on their sense of smell, you may need to tempt these pets with pungent smelling foods to keep them eating.
I treat allergic Rhinitis with nasal corticosteroid spray such as Nasocort. Introducing an ophthalmic or nasal saline rinse into the nostrils three times a day is also helpful. Antihistamines such as Benadryl may also help.
Foreign bodies that have lodged in the nose require different treatment. The drainage from such objects becomes thick and yellow-greenish in color.
My biggest concern is one-sided drainage in older dogs and cats that persists beyond a week or two. Many of these cases have proven to be tumors growing within the nasal passage. A good number of these tumors are malignant. It is quite difficult to obtain a small portion of these masses for pathological examination. If they do turn out to be malignant, I refer the pets on to a veterinary oncologist for treatment.