Nasal Discharge & Sneezing
This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian.
The nostrils open into 2 major air passages that end in the throat. The nasal passages are filled with very fine scrolls of bone called turbinates. The turbinates are covered in pink tissue (mucosa) similar to the lining of the mouth. Air is warmed and filtered as it passes through the turbinates in the nose on the way to the lungs. The roof of the mouth (hard palette) separates the mouth from the nasal cavity. Anatomy of the nose (dog / cat).
Front-on view of the nose and upper front teeth of a dog showing the delicate, complex structure of the turbinate bones.
There are several causes of nasal discharge in both dogs and cats.
The age of the pet and the presence or absence of other signs influences which causes are more likely. Young puppies and kittens that are still nursing their mothers that have milk coming from their nose should be examined for a cleft palette.
Young animals with infections caused by viruses or bacteria may have nasal discharge and sneezing in addition to other signs such as cough, lack of appetite, depression and discharge from the eyes. Pets with swallowing abnormalities may inhale food causing pneumonia (lung infection) and nasal discharge.
Cats can develop polyps in the back of the throat originating from the Eustachian tube that connects the throat to the ear. These polyps can cause nasal discharge and gagging.
Older, middle to large-sized dogs with long noses are more likely to develop nasal cancer. Dogs that spend time outdoors are more likely to inhale foreign matter into the nasal passages.
The appearance of the discharge varies with the cause. Nasal discharge can be clear (serous), gray and cloudy (mucoid), thick and green (purulent), or bloody. The discharge may come from one or both nostrils.
Clear (serous) nasal discharge, usually accompanied by sneezing, may be seen in animals with allergies. The discharge usually comes from both nostrils and is intermittent. Often other allergic signs are seen as well, such as scratching, hair loss, face rubbing, and paw licking. Allergies may be seasonal.
Nasal mites are small (~ 1mm) bugs that can cause sneezing and nasal discharge.
Occasionally the mites may be seen as small white to light tan specks around the nostrils. The discharge is usually clear, and comes from both nostrils.
Mucoid and purulent nasal discharges are caused by:
- the presence of foreign matter (such as grasses or weeds) in the nose
- infection of the roots of the upper teeth
- fungal infection
- nasal cancer
Foreign matter in the nose usually causes sneezing and pawing at the nose when first inhaled but over time you may only see nasal discharge and occasional sneezing.
Pointed grass seeds like this fox-tail awn can be inhaled as the dog sniffs. The awn can get stuck in the nasal passage or can travel through the nasal passages, leave the nose in the back of the throat and then enter the airways, traveling to the lungs.
If the discharge contains blood, then fungal infection or cancer are most likely to be present. An exception to this rule is that violent sneezing from any cause can cause temporary bleeding from the nose. But if bleeding is NOT caused by sneezing, then fungal infection or cancer are the most likely causes. Nasal bleeding can be part of a body-wide bleeding problem in which case bleeding or bruising are seen in locations in addition to the nose. Tooth root abscesses and nasal foreign matter tend to cause a one-sided nasal discharge. Other causes of nasal discharge may begin from one nostril and progress to both nostrils as the disease worsens.
Laboratory tests on blood and urine do not usually reveal the cause of nasal discharge, although these tests are often performed to evaluate the general health of the pet prior to anesthesia. Some pets with allergies or nasal mites may have increased eosinophils, a type of white blood cell.
The nasal discharge can be looked at microscopically. The discharge that comes out the nostril(s) usually just contains dead cells and bacteria. Occasionally looking at the discharge will discover a cause. Since this test is easy to do, it may be performed even though most often it does NOT provide an answer.
Tests that may be performed to determine the cause of nasal discharge include:
- x-rays of the skull
- looking up the nostrils with a flexible tube called a rhinoscope (only feasible in larger dogs)
- looking at the back of the nose with a small mirror placed in the throat
- washing fluid through the nose
- biopsy through the nostrils
- CT scans of the skull
The nasal cavity is very difficult to examine. The disease in the nasal cavity can be “hidden” within the small passages of the turbinates.
Skull x-rays or CT scans of the nose are performed to look for destruction of the turbinate bones in the nose. CT scans are more sensitive and will detect destruction earlier than plain x-ray films. When the turbinate bones show damage, the most likely diagnosis is fungal infection or cancer. X-rays or CT can also detect spread of disease from the nasal passages into the air-filled cavities called sinuses.
X-ray and CT scan can also detect infection of the tooth roots, which can cause a hole to form between the roof of the mouth and the nasal passage(s). This hole is called an oral-nasal fistula.
Vigorously forcing fluid through the nose or passing a stiff plastic tube up the nostril, can be used to collect cells for microscopic evaluation and fungal culture. There are also blood tests available that can tell if an animal has been exposed to a fungus. Unfortunately this test can be difficult to interpret as some normal pets with have blood tests that are positive for fungal exposure. Vigorous flushing of fluid from the back of the throat through the nostrils, may force foreign matter out the nose.
Because of the complex structure of the nose, a tumor, fungal infection, or foreign matter can “hide” and can be missed despite a careful examination of the nose. If all other tests fail to provide a diagnosis, surgical exploration of the nose may be required.
The treatment of nasal disease depends upon the cause. Drugs can be given to that kill nasal mites. Holes into the nasal passage caused by infection of the roots of the teeth are treated by dental cleaning and sometimes tooth removal.
Fungal infections are usually caused by Aspergillus in dogs, and Cryptococcus in cats. Fungal infections are treated with anti-fungal drugs and require long-term treatment of many months. Cats with nasal fungal infection should be tested for the feline leukemia virus.
Nasal tumors are difficult to treat. The complex structure of the nose makes it impossible to surgically remove a tumor from inside the nose. Radiation therapy can be used to slow the growth of tumors in the nose. Radiation therapy is only available in select locations in large cities or Veterinary Schools. Nasal tumors are not usually responsive to anti-cancer drugs. Nasal tumors can grow into the brain causing changes in behavior or seizures. They may also break through the bones of the face causing distortion of the face.
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