What are the causes of sneezing and nasal discharge?
Although these two clinical signs may not always appear together, both are associated with disorders affecting the nasal cavity and/or nasal sinuses. While occasional sneezing is perfectly normal, repeated bouts of vigorous sneezing may indicate irritation of the nasal cavity caused by foreign bodies, viruses, air-borne irritants or rarely, nasal mites.
Nasal discharge may be caused by a number of different conditions. These include infection of the nasal cavity or nasal sinuses by viral, fungal and bacterial agents, masses such as polyps or tumors, inflammation caused by foreign bodies or allergies, irritation caused by nasal mites, and conditions extending from the mouth, such as abscessed tooth roots or oral tumors. Occasionally, nasal discharge may be associated with diseases that are located deeper within the airways.
How do we determine the underlying cause of sneezing or nasal discharge?
"A complete history and physical examination of your pet will provide vital clues."
A complete history and physical examination of your pet will provide vital clues. Details such as the duration of the sneezing or nasal discharge, as well as the characteristics of the discharge (color, thickness, presence of blood etc.), may be important. For example, a healthy dog that experiences a sudden episode of severe sneezing may have inhaled a foreign body, such as a grass awn, into the nostril. A cat with longstanding nasal discharge and a swelling over the nasal region may have an underlying infection or a tumor.
It may also be helpful to perform a series of basic screening tests to gather more information about the cause of your pet's sneezing or nasal discharge. In some instances, additional diagnostic procedures may be needed to reach a definitive diagnosis before effective treatment can be started.
What might these screening tests include?
Depending upon your pet's history and physical examination findings, these screening tests may include a complete blood count (CBC), a coagulation panel, a serum biochemistry profile, a urinalysis, a microscopic examination of the nasal discharge, radiographs of the head and/or chest, and fungal or viral testing.
If a nasal foreign body is suspected in a pet that is sneezing but is otherwise healthy, visual inspection of the internal nasal passage, using a special piece of equipment called a "scope", may be all that is needed to make a diagnosis. This procedure is called "rhinoscopy" (See below).
What could these tests indicate?
The CBC includes an evaluation of the cellular components of blood, including the red blood cells, the white blood cells, and the platelets. A hematology (blood) analyzer will provide us with the total numbers of these cells, and evaluation of a blood smear will allow us to look at the physical characteristics of these cells. The CBC might reveal reduced numbers of red blood cells, which could be due to blood lost in a bloody nasal discharge. A very low platelet count might be the cause for a sudden onset of a bloody nasal discharge. A high white blood cell count might indicate infection or inflammation in the nasal cavity.
The serum biochemistry profile andurinalysis give us an overall assessment of how well the various organ systems of the body are working, including the liver and kidneys. These tests are not likely to provide us with a definitive diagnosis for your pet's nasal discharge or sneezing. However, some diseases affecting the nasal cavity may have systemic (whole body) effects, and it is important to determine whether other organs of the body are involved.
"...prudent to evaluate your pet's overall general health ... before more complex diagnostic procedures are performed."
Since some diagnostic procedures require a general anesthetic, it is also prudent to evaluate your pet's overall general health through these tests to ensure that there are no other conditions (for example kidney disease) that need to be corrected before more complex diagnostic procedures are performed.
A coagulation profile and a von Willebrand's factor test are indicated if bleeding is noted in association with the sneezing episodes or if blood is a major component of the nasal discharge. A coagulation profile will evaluate the activity of the proteins involved in blood clotting and allow us to determine if the bloody discharge is a result of a deficiency in these coagulation factors.
Inherited deficiencies in coagulation factors are found in certain types of purebred dogs; for example, deficiency of von Willebrand's factor deficiency is common in Doberman Pinschers. However, acquired problems with blood clotting may occur in any animal, especially if advanced liver or kidney disease is present, or if the pet has recently eaten rodenticide (rat poison).
Microscopic examination (or cytological evaluation) of the nasal discharge may provide information about the underlying cause. Draining material collected from the nose using a cotton-tipped swab, is spread onto a microscope slide and then sent to a veterinary pathologist for evaluation. Cytology provides information about the types of tissue cells that are present, including inflammatory cells or cells with cancerous changes, and indicates if infectious organisms are present in the sample.
Chest radiographs may be used to evaluate the lungs if we suspect that the sneezing or nasal discharges are manifestations of lower respiratory tract disease rather than problems just within the nasal cavity. If a tumor of the nasal cavity is suspected, then radiographs of the chest may give us information about whether the tumor has spread to the lungs or chest cavity.
Testing for specific infectious agents such as viruses and fungal agents may be useful in some patients.
Infection with feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV) may make cats more susceptible to infections caused by respiratory viruses or fungal organisms. If a fungal infection is strongly suspected but cannot be confirmed based on cytological evaluation of material from the nasal cavity, then testing of a blood sample for the presence of antibodies against specific fungal organisms can be performed.
What additional tests may be required?
"Additional diagnostic tests are often necessary to determine the specific cause of a pet's nasal discharge."
Additional diagnostic tests are often necessary to determine the specific cause of a pet's nasal discharge. These tests may include radiographs of the head and nasal cavities, CT (computerized tomography) scans, rhinoscopy, tissue biopsy, or bacterial culture.
Radiographs of the nasal cavity usually require that your pet be sedated or given a general anesthetic so that the head can be properly positioned to allow optimal visualization of the nasal cavities. The radiographs will allow us to assess if there is bone loss or if masses are present.
Computerized tomography (CT) scans are only available at veterinary referral facilities. CT scans allow a more detailed visualization of the nasal sinuses and can often detect small lesions that are not evident on radiographs.
Rhinoscopy allows visualization of the nasal cavity by use of a small, flexible endoscope. A general anesthetic is required for this procedure. Rhinoscopy may allow us to see masses, foreign bodies, and the general characteristics of the nasal lining cells (nasal mucosa). Should masses or other abnormalities be noted, rhinoscopy can be used to guide us to the appropriate site for tissue sampling.
Samples of lesions within the nasal cavity can be obtained by tissue biopsy, fine needle aspiration (also called fine needle biopsy), and nasal flush techniques. The method selected will depend upon the nature of the material that we are attempting to harvest.
For example, a solid nasal mass is probably best sampled by removing a piece of tissue from the mass using biopsy forceps. This tissue biopsy is then submitted to a veterinary pathologist for evaluation. The advantage of obtaining a tissue fragment is that tissue architecture is preserved, which often makes the sample more diagnostically useful.
Occasionally individual cells from masses can be harvested by fine needle aspiration. This technique uses a fine gauge needle attached to a syringe to withdraw or aspirate cellular material from the site. This material is then submitted to a veterinary pathologist for evaluation. Fine needle aspiration is less traumatic than a tissue biopsy but the disadvantages are that architectural features are lost, and the collected material is not always diagnostic.
Finally, a nasal flush technique may be used. The flush technique involves instilling a quantity of sterile fluid into the nasal cavity and then quickly re-collecting the fluid. Cells and other material within the nasal cavity will be dislodged by the fluid, which are then collected and sent to a veterinary pathologist for evaluation. The nasal flush technique also allows us to obtain material from deeper within the nasal sinuses for purposes of bacterial culture.
"...surgical exploration of the nasal cavity may need to be performed."
If we are unable to determine the underlying cause of your pet's sneezing or nasal discharge by these techniques, then surgical exploration of the nasal cavity may need to be performed. Such a procedure would generally require the services of a specialized veterinary surgeon.