ALISON LAURIE-CHALMERS: Vet Speak columnist explains why chronic respiratpory infections can be so serious for cats
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Buttercup was a lovely, petite tortoiseshell cat. She was a frequent visitor to the clinic, as she had chronic rhinitis symptoms.
Buttercup had contracted “cat flu” as a kitten before her owner had acquired her, and ever since she’d been prone to flare ups of her debilitating runny nose and sneezing.
There are many causes of upper respiratory tract disease. Feline viral rhinotracheitis (feline herpesvirus) and feline calicivirus are the main cause. These respiratory viral diseases are common in young cats and are highly contagious. They are transmitted through air droplets, or by direct contact with an infected cat through contact with nasal or ocular discharges, or via contaminated bedding and food bowls. The viruses may survive in a favourable environment for up to 24 hours for herpes virus, and up to 10 days for calicivirus. Over 85 per cent of respiratory diseases are caused by the feline herpes virus 1, which causes the respiratory infection known as rhinotracheitis. These viruses can persist in some cats, known as carriers, for weeks, months, or years. Some cats that have been infected with the herpesvirus or the calicivirus will remain carriers for life.
These viral infections can cause severe mucous membrane inflammation and damage, leaving the cases susceptible to secondary bacterial infection. The viral infection damages the protective mucous membranes of the respiratory tract and eyes, and allows bacteria to invade these damaged tissues, thereby causing persistent clinical signs. This can lead to chronic persistent or intermittent signs with sneezing, eye and nasal discharges and congestion. In severe cases this may spark infection of the nasal turbinate bones, an osteomyelitis, a bacterial infection of th fine bones in the nasal sinuses.
Vaccinated cats that have not been given the appropriate annual booster vaccines may become infected with one or more of these viruses, and later in life may exhibit chronic post-viral rhinitis and conjunctivitis symptoms. Or, if they have been previously exposed to respiratory viral infection as kittens, they may have chronic or recurrent signs.
There are other pathogens. Chlamydophila Felis and Bordetella are bacteria that can also cause primary respiratory infections. in ca A group of organisms called Mycoplasma can cause primary respiratory and eye infections, or play a secondary role, along with other bacteria such as Pasteurella, Streptococci and Staphylococci
As well as bacteria, some fungal infections can cause chronic upper respiratory tract disease. Also, cancers affecting the upper respiratory tract are rare but may need ruled out in certain cases. In a few cats, benign, non-cancerous polyps may cause chronic sneezing and discharge. Other causes of upper respiratory tract inflammation may need to be ruled out with further investigations and imaging, such as allergic rhinitis, trauma, foreign bodies trapped in the nose, or even dental disease.
A runny or “stuffed-up” nose is the most common clinical sign in cats with chronic upper respiratory tract infections. The nasal discharge tends to be thick and often is greenish yellow, and it may also be blood tinged. Because smell is so important to them, affected cats have a poor appetite and lose weight. There may also be inflammation in the throat, making swallowing uncomfortable and this can lead to salivation. Affected cats can also have a chronic discharge from one or both eyes. In severe cases, facial swelling and resentment of touching the face may occur due to pain. Flat-faced cat breeds, such as Persians, find this congestion extremely debilitating. In other cases, these chronic signs are relatively mild, such as episodes of sneezing accompanied by a clear nasal or ocular discharge. Cats with mild symptoms usually have normal appetites.
Some of the common symptoms are: runny nose and sneezing; difficulty breathing; runny painful eyes and conjunctivitis; keratitis; eye ulcers; gingivitis and mouth sores; lack of appetite; lethargy; fever and lethargy. These signs will be more severe in immunocompromised cats. If the infections are chronic or recurrent, then tests for the presence of feline immunodeficiency virus, or feline leukaemia virus are advised, both of which may weaken the immune system and predisposing the case to recurrent respiratory infections.
Investigations for chronic cases may involve blood samples, or swabs of the nose or eye discharges for laboratory examination, and in some cases imaging, endoscopy and biopsies may be required.
Post-viral chronic cases are very difficult to manage, and controlling rather than curing the disease is often the main goal. Antibiotics, anti-inflammatory treatments, targeted nutrition supplements and anti-viral medications are some of the methods usedtypically give an initial dramatic improvement that is frustratingly often short lived. Anti-inflammatory treatments can sometimes be of some benefit. Targeted nutritional supplements that aid in mucous membrane repair and maintenance and general immune system stimulation can be helpful, especially in chronic viral infections. And anti-viral and immune-stimulating medications may be beneficial in some severe recurrent cases. Some cases remain chronic or recurrent. The goal in these cases is to reduce a cat’s discomfort through long-term or periodic medication to improve quality of life. Good care at home is also important, keeping the cat’s face clean and clear of discharges, and encouraging them to eat by providing nutritious warmed up food that is strong smelling, such as fishy flavours.
Buttercup responded well to treatments in watching out for any recurrent respiratory symptoms. If you are concerned about any upper respiratory disease symptoms in your cat, then do contact your vet.
• Alison Laurie-Chalmers is a senior consultant at Crown Vets.
