The nose knows - Nasal disease in cats - Article 1

Nasal disease in cats can be extremely difficult to diagnose, but has been made significantly easier by the use of computed tomography and rhinoscopy.

We often receive calls late in the day, typically towards closing time, from referring vets wishing to have a feline patient seen at short notice for specialist consultation by the Cardiorespiratory Department at SARC.

Under non-emergency circumstances appointments are booked well in advance and owners make their way in an orderly manner to SARC for cardiac or respiratory workup. However, a dyspnoeic cat seen at 5pm on a Friday afternoon may not have the luxury of waiting until the next available appointment on Monday. Primary care vets are wanting both (non specialist) emergency stabilisation and specialist cardiorespiratory workup at what is well known to be the worst possible time of the week.

It is under these circumstances that the integration between the Emergency and Critical Care Department and the Cardiorespiratory Department at SARC comes to the fore.

We see a great number of cases in need of a ‘two speed’ service; firstly the hurried transfer and emergency stabilisation (inevitably during primary care consulting times or nearer to closing time), followed by the required specialist cardiorespiratory workup recommended by the primary care vet and expected by the owner.

Rather than offering either one or the other, with neither individual service being sufficient, we are able to provide a service where the Emergency and Critical Care Department can stabilise and undertake basic diagnostics (if not already performed by the referring vet) followed by a specialist workup soon after or early the next morning, depending on the condition of the patient.

Thus both problems can be solved under this difficult circumstance, giving primary care vets the best of both worlds. The types of cases we see under this circumstance include presentations of effusions, pulmonary oedema, pneumonia, ascites, general dysponea, collapse and more.

Cases are typically stabilised as best as possible for transfer at the primary care veterinary clinic or sent direct to the Emergency and Critical Care Department at SARC. If fit to travel, cases are then transferred and admitted for continuing stabilisation. If not fit for transfer, we are happy to discuss the case over the phone to assist in improving the outcome.

A varying range of diagnostics is typically completed at the primary care practice, and patients often arrive with basic screening, bloodwork and imaging already complete, though we are obviously happy to accept cases at any stage of workup.

Once patients are admitted, further emergency treatment can continue while the Emergency and Cardiorespiratory teams formulate a further diagnostic and treatment plan. This often involves telemedicine to view radiographs or blood results if specialist cardiologist Richard Woolley is not already on-site. Consultation during this stabilisation and preparation period means that when specialist cardiologist Richard Woolley is on-site he is often fully apprised of all important details.

If owners are present they are welcome to attend during further cardiac workup, including specialist cardiac ultrasound, meaning that there is a seamless transition between emergency care and further specialist cardiac workup. Once workup is complete, further emergency and critical care can then proceed, again in a seamless transition back to the Emergency and Critical Care team.

During this process owners communicate with the same staff in the same facility; all of whom have access to the same medical records and are pursuing the same treatment plan. This simplifies the communication and decision making process for owners, who can concentrate on key decisions in what is already a difficult and fast-changing situation.

If you have questions about advice or referral for urgent cardiorespiratory cases, please feel free to contact us at any time.

I have to admit I previously found cats with chronic nasal disease challenging. The big problem with nasal disease is that the nasal tissues are encased in bone and are well protected from the environment, as well as the veterinarian!

Good nasal radiographs are not only difficult to obtain but are often difficult to interpret. This is due to the small size of the feline nasal passage causing marked superimposition of the nasal structures, making identification of lesions difficult.

CT has markedly improved the ease of lesion identification in the nasal cavity by creating cross sectional anatomic images so superimposition is not an issue. Also, with the advent of post processing software (allowing the release of the inner nerd!), the CT images can be manipulated giving views from different angles and 3-dimensional reconstructions. CT imaging, like nasal radiography, is performed under general anaesthesia, and the improvement in image quality is more than worth the moderate increase in cost associated with CT.

CT should be performed prior to anterior rhinoscopy (as anterior rhinoscopy can cause damage to the nasal turbinates appearing as pathological changes on CT), but we usually examine the posterior nares before we do further imaging because the latter examination is very quick and easy and may obviate the need for CT or anterior rhinoscopy, e.g. if a foreign body is found in the posterior nasal cavity that can be removed.

Nikita, a 9 year old female neutered domestic short hair cat presented to the cardiorespiratory Service with a history of a chronic nasal discharge and increased upper respiratory noise. Various courses of antibiotics had moderately improved the degree of nasal discharge but there had been no real improvement in the increased upper respiratory noise.

At this point I would like to mention the use of doxycycline in respiratory disease. Doxycycline is a very useful agent in respiratory disease as it is not only active against Bordella sp. but also appears to have an immunomodulatory action. The recommended dose of doxycycline for both dogs and cats in respiratory disease (5-10mg/kg PO 12hrs) is higher than the dose stated on the box. Doxycycline can cause vomiting in some patients and has been associated with oesophageal strictures in cats, but administering doxycycline with food can prevent both these side effects.

Nikita was admitted for investigation of the nasal disease with the view to performing CT and rhinoscopy. Examination of the posterior nares (see image above) revealed a soft tissue mass partially obstructing the posterior nares. Biopsies of the mass were taken using biopsy forceps placed though the biopsy channel of the rhinoscope. Due to a mass being identified CT was performed to assess its extent through the nasal cavity. The CT (reconstructed to show a sagittal plane) revealed the mass to be situated above the soft palate extending forward over the hard palate (see accompanying images of a normal CT (middle) vs Nikitas’s (bottom)). Images of the rostral nasal cavity demonstrated increased fluid density due to mucus accumulation as a result of reduced drainage caused by the caudal mass. No evidence of the soft tissue mass was present in the rostral nasal cavity.

The biopsies taken from the mass in the posterior nares revealed cells consistent with a round cell neoplasia, most likely lymphoma. Nikita’s owners are currently considering surgery, chemotherapy and radiotherapy, the combination of which can have a very favorable outcome.

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