Chronic (long-term) upper respiratory tract (URT) disease (also known as chronic nasal discharge) is a relatively common problem in cats, and can have many causes.
The syndrome refers to chronic disease affecting the nose (nasal cavities) or the nasopharynx (the air passage immediately behind the nose). One of the most common forms is termed chronic post-viral rhinitis (inflammation or infection in the nose). In this condition, viral infection (eg, acute upper respiratory infection caused by feline herpesvirus – FHV or feline calicivirus – FCV) causes damage to the delicate mucosal lining inside the nose, and even to the fine turbinate bones within the nose; but the chronic signs relate to secondary bacterial infection that occurs as a result of the damaged nasal passages. This can lead to chronic persistent or intermittent signs with sneezing, nasal discharge and nasal congestion.
What are the common causes of chronic upper respiratory tract disease?
Many different diseases can cause long-term damage to the nose or nasopharynx and result in clinical disease. Some of the most important causes include:
- Post-viral or idiopathic rhinitis – Acute upper respiratory infections with FCV or FHV are common in cats, especially young cats. The severity of these infections varies greatly between cats, but in some cases (especially with FHV infection) the viral infection may do permanent damage to the delicate mucosal lining of the nasal cavities and can also damage the underlying bone. This may result in permanent changes that leave the nasal cavity susceptible to long-term recurrent secondary bacterial infection. This is termed post-viral rhinitis (nasal inflammation), and is thought to be one of the most common causes of chronic rhinitis in cats. In severe cases, the bacterial infection can spread to the underlying bone and cause an osteomyelitis (infection within the bone). The sinuses in the bones around the nose can also be affected in chronic rhinitis, so the term rhino-sinusitis is sometimes used. It is not known how many cases of non-specific or idiopathic rhinitis are due to post-viral changes, but it is suspected that this may account for a substantial proportion.
- Fungal infections – the single most common nasal fungal infection in cats is with the organism called Crytpococcus neoformans or Crytpococcus gatii. Infections with Crytpococcus gatii are more common in tropical and sub-tropical climates whereas Crytpococcus neoformans has a wider distribution. Infection is acquired through inhalation of the organism from the environment. Other fungal organisms can also occasionally cause nasal infections in cats including Aspergillus and other organisms.
- Inflammatory polyps – occasionally, multiple polyps (small inflammatory swellings/growths) arise within the nasal cavity. More commonly a large polyp arising from the middle ear or eustachian tube (the small tube that connects the nose to the middle ear) develops and this may grow within the nasopharynx causing obstruction to breathing.
- Neoplasia (cancer) – the two most common forms of tumour affecting the nasal cavity are lymphoma (a solid tumour of lymphocytes, a type of white blood cell) and adenocarcinoma.
- Foreign bodies – in cats, the most common nasal foreign bodies are plant material such as blades of grass or grass seeds. These may be inhaled into the nose in some cases or may also become lodged in the nose after being vomited in a cat which has eaten them.
- Allergic rhinitis – although uncommon, some cats will develop an allergic rhinitis that is similar to so-called ‘hay fever’ in humans.
- Dental disease – sometimes severe dental disease may result in disease affecting the tooth root (e.g., abscess development) that may affect the nasal cavity.
- Other conditions – a variety of other disease may occur, including disease due to facial conformation (e.g., extreme ‘flat-faced’ Persian cats), nasopharyngeal stenosis (where the nasopharynx becomes abnormally narrowed), and trauma.
What are the clinical signs of chronic URT disease?
The main signs of nasal and nasopharyngeal disease are:
- Nasal discharge
- Dsypnoea (or difficulty in breathing)
- Sonorous breathing (‘snoring’) due to difficulty in breathing
- Stertorous breathing (noisy breathing through the mouth due to obstruction to air flow through the nose or nasopharynx)
The nature of some of these signs may help your vet uncover the underlying cause of the disease:
- Does it affect one or both sides of the nose?
- Is there discharge from one or both nostrils?
- What is the nature of the nasal discharge – is it clear, watery, mucoid, purulent?
- Is there any blood present in the discharge? (usually, but not always, a sign of more severe disease such as fungal infection or neoplasia)
- Is there any facial swelling and change to the conformation of the face or nose? (usually, but not always, a sign of more severe disease such as fungal infection or neoplasia)
- Is there any ocular discharge (‘runny eyes’) or involvement of the eyes?
- Is there any evidence of involvement of the ears? (sometimes seen with inflammatory polyps in particular)
- Is there any enlargement of the lymph nodes around the head and neck? – if so, these may need to be investigated too
- Has there been any marked change in appetite or weight – cats with URT disease often have a reduced appetite, but marked weight loss may suggest a more severe disease
- Did the clinical signs start suddenly or gradually?
- Have the signs been getting progressively worse?
These are all questions your vet will probably ask, so it is a good idea to try to write down as much information as possible before you go to the vet with your cat.
Investigation of chronic URT disease in cats
Sometimes, on the basis of the history of your cat, the presenting clinical signs and the clinical examination, your vet may have a very good idea of what the underlying problem is and further investigations may not be necessary. However in other cases, and especially with severe disease, where clinical signs are getting worse, or where there is evidence of disease elsewhere as well, further investigations may be required.
What investigations are needed will vary from one case to another, but may include:
- Blood and urine tests – including investigation for FeLV and FIV when appropriate. Blood tests may also help to detect certain other infectious causes (such as Cryptococcus infection).
- X-rays of the nose, pharynx, chest and possibly abdomen. These can be very valuable to look for changes within the nose and elsewhere. In some situations more advanced imaging (such as CT or MR scans) will be available and used – these can give much clearer images of the internal structures in the nose and pharynx.
- Endoscopy (rhinoscopy) – while anaesthetised to take X-rays, your vet will also examine your cat more thoroughly – often by using a small endoscope placed through the opening of the nose and/or through the mouth to look at the back of the nose. This enables direct visualisation of some of the structures in the nose.
- Biopsy – frequently a valuable technique, small biopsies can be collected from tissues within the nose to be examined histologically by a pathologist, and also for culture to see what organisms may be present. Collecting biopsies will cause a small amount of bleeding, but usually this is very minor.
It is also important to remember that many of these tests may return normal or non-specific results in cases of chronic post-viral rhinitis, as this is a disease that is often diagnosed by excluding other possible causes (with supportive evidence from biopsies etc.).
Treatment of chronic URT disease
Treatment of chronic URT disease will depend on the underlying cause. Some diseases will be curable, some manageable (to control clinical signs), but in some cases treatment may not be possible or appropriate for the cat. Examples of some treatments include:
- Tumours – adenocarcinoma may be difficult to treat (although radiation therapy may be an option in some), but lymphoma in the nose may respond well to therapy with drugs (chemotherapy) and/or radiation therapy in some cases
- Fungal infections – these may respond well to appropriate therapy, but in some cases anti fungal drugs need to be combined with surgery to remove infected tissues
- Inflammatory polyps – these will often respond well to surgical removal, although – some cases may be relatively easy to resolve whereas in others more complex surgery may be needed
- Foreign bodies – these can usually be removed under anaesthesia, although in some cases surgical access to the nasal cavity may be required
- Idiopathic/post-viral rhinitis – these cases can be more difficult to manage and realistically controlling rather than curing the disease is the primary goal. Treatment options that may be considered include:
- Intermittent antibiotic use – the disease is often associated with secondary bacterial infection and antibiotics usually improve clinical signs. However, signs often do not resolve completely with antibiotics and/or recur again after a period of time
- Nebulisation therapy can help – nebulisers can be obtained from your vet or a pharmacist and produce a cloud of very fine water droplets. These are breathed in and help to moisten the airways in the nose – this is helpful in chronic rhinitis as nasal secretions can be very thick, so nebulisation will improve this and make sneezing more productive
- Proprietary human nasal decongestant drops should be avoided – these can be toxic to cats and/or cause more severe disease
- Some cats may benefit from having their nasal passages gently flushed and cleaned under anaesthetic from time to time
- In some cases, the use of topical (nose drops) or systemic (tablets or injectable) corticosteroids may be of benefit – these drugs help to relieve inflammation and in some cases of idiopathic rhinitis (e.g., where there is inflammation termed ‘lymphoplasmacytic’ – a type of inflammation that may suggest an overactive immune repsonse) their use may be valuable
- Good nursing care is also extremely important, keeping the cat’s face clean and clear of discharges, and encouraging it to eat by providing warmed up food that is strong smelling