66 | How to nurse your cat ‘flu patients like a pro: the vet nurse’s guide to feline respiratory disease complex

PodcastRespiratory
Written By Laura Jones

Today we’re talking about a really common, commonly misunderstood and often frustrating disease - feline respiratory disease complex, aka FRDC or cat ‘flu.

 


When I think about those ‘flu cases, I think back to sweating in PPE in a makeshift isolation room in my earlier nursing days, spending countless hours cleaning nasal discharge, creating steam baths outside of kennel doors, and tempting tiny kittens to eat. In fact, I ended up taking two of them home - Nigel and Mavis, the two cats on this podcast cover - 12 years ago.

We know this is a disease that is MADE for nursing - there is so much we can do to support these patients. And as always, giving that great care starts with understanding what ‘flu is, and how we manage it.

Ok, so what IS cat “flu”?

Like many other diseases, cat ‘flu’ isn’t a disease in itself - it’s a complex including various infectious diseases that affect the respiratory tract (mostly the upper respiratory tract), hence the ‘official’ name of Feline Respiratory Disease Complex.

These diseases cause rhinosinusitis, conjunctivitis and oral ulceration alongside increased lacrimation, salivation and pyrexia.

Let’s start with the big ones: herpes and calicivirus.

The two specific pathogens we think of in ‘flu cases are feline calicivirus (FCV) and feline viral rhinotracheitis (aka feline herpesvirus-1 or FHV). These highly contagious viruses enter the host through the oral or nasal conjunctive and replicate within the nasal tissues and tonsils.

Clinical signs begin shortly afterwards, and patients will actively shed the virus for at least this entire period. Many cats will continue to shed the virus after clinical signs stop and will experience latent infection without clinical signs. During times of stress, illness or immunosuppression, the virus can reactivate and cause clinical signs - this is termed recrudescence.

Many cats with chronic rhinitis are thought to have previous herpesvirus or calicivirus infections, even if they do not currently show signs of active infection.

Infection with both FCV and FHV-1 is most commonly seen in kittens and unvaccinated, stressed or immunocompromised adult cats.

And then we have bacterial infections.

Mycoplasma felis, Chlamydia felis, chlamydia psittaci and Bordetellabronchiseptica have all been identified as potential causes or complicating factors in cat ‘flu. 

These can be primary bacterial pathogens, but they’re more commonly seen alongside viral infection. As the virus damages the respiratory mucosa, opportunistic bacteria can easily cause a secondary infection, complicating clinical signs and the patient’s treatment.

So those are our cat ‘flu diseases - and most of them cause similar clinical signs.

In most cases, regardless of the exact pathogen our patient has, they’ll present with:

  • Pyrexia

  • Sneezing

  • Mucopurulent or serous nasal discharge

  • Conjunctivitis

  • Rhinitis

  • Salivation

  • Anorexia

  • Dehydration

Cats may also develop ulcerative keratitis, epiphora, conjunctival oedema or hyperaemia and blepharospasm, and severely affected patients may develop ulcerative stomatitis.

FHV-1 can also cause bony changes to the nasal turbinate bones, causing long-term nasal changes, chronic rhinitis, and an increased risk of concurrent bacterial infection. 

Calicivirus is a little more complex. There are many different strains of calicivirus, and each causes different clinical signs. Some cause very mild signs, others ulceration and gingivostomatitis, and others pulmonary oedema and pneumonia. Two strains cause no respiratory signs, instead causing shifting leg lameness, pyrexia, and joint pain - referred to as ‘limping syndrome’.

Mycoplasma felis can affect the eyes and upper respiratory disease, usually causing marked conjunctival oedema and less severe nasal signs.

It’s not possible to differentiate between FHV-1 and FCV infection based on clinical signs and examination alone. These patients will need to have specific infectious disease testing if you want to isolate the pathogen involved.

Speaking of those diagnostics

A presumptive cat ‘flu diagnosis is made on the patient’s clinical signs and confirmed with further diagnostic tests. 

First, we’ve got infectious disease testing.

The preferred method of infectious disease testing is polymerase chain reaction (PCR) testing, where swabs from the oropharynx or conjunctiva are tested for pathogenic DNA. Usually, a respiratory panel that tests for FHV-1, FCV, chlamydia, mycoplasma, and bordetella is submitted.

And then there’s bloodwork.

Whilst routine biochemistry and haematology don’t show specific changes, complications like anorexia and dehydration are common. Any patient with chronic clinical signs or who is systemically unwell should have full bloods performed.

Since upper respiratory diseases are commonly associated with immunosuppression, it may also be useful to know the patient’s FeLV/FIV status (if it is not already known).

And if needed, there’s additional diagnostic procedures we can perform.

As we discussed in episode 65, diagnostic imaging and rhinoscopy may be indicated. This is usually reserved for patients with chronic clinical signs not responsive to supportive care, since viral infection is generally self-limiting in the short term.

Patients with chronic rhinitis due to historical viral infection may also benefit from therapeutic nasal flushes to manually clear mucous and nasal secretions.

Whilst diagnosis is relatively straightforward, treatment and nursing care aren’t always.

These patients need a LOT of intensive supportive care, and it can be a very nursing-heavy task. Whilst most of our treatment is supportive, there are a few specific drugs we reach for in these patients. These include:

  • Topical antiviral agents for corneal lesions associated with FHV-1

  • Systemic antiviral agents for patients with chronic FHV-1 (famciclovir)

  • Antibiotics for treatment of specific secondary bacterial infections (doxycycline is commonly used since it is effective against chlamydia and mycoplasma)

Lysine has also been suggested as a treatment for FHV-1 since it interferes with viral replication, however there’s not a great evidence base for this, and some studies do contradict each other.

Aside from this, treatment aims to support the patient’s overall health while they recover. 

Analgesia should be provided to any painful or potentially painful patient (if they’re not eating, it’s worth trialling since those ulcers are going to be sore!), antiemetics can be considered if patients are nauseous, and fluid therapy should be administered based on the patient’s hydration status.

Nursing management is intensive - and we make an enormous difference to these patients.

Particular areas to focus on include nutrition, fluid balance, special sense care and cleaning, monitoring and infection control.

Nutrition is an essential part of supporting these patients. Many are kittens with increased nutritional needs, and almost all of these patients are inappetent. If they’re not eating sufficient volumes, consider a feeding tube and get enteral nutrition on board.

The anorexia, nasal secretions and increased salivation can potentially worsen dehydration, so fluid therapy monitoring is vital. Fluid needs change during hospitalisation, so reassess your patient regularly.

Patients benefit from regular nebulisation with saline and cleaning of their ocular and nasal secretions. Keeping them clean might seem basic, but it makes an enormous difference and is fundamental to them feeling better and wanting to eat. Regular ocular lubrication should also be applied since these patients are at increased risk of corneal ulceration.

Then, we need to think about infection control. This is a highly contagious airborne disease, so patients should be housed in an isolation unit (where they can still be closely monitored) and strictly barrier nursed.

And whilst all of this treatment is great, there’s one thing better - preventing infection in the first place.

Whilst not all of these pathogens can be vaccinated against, there are a few that can. 

FHV-1 and FCV are essential core vaccines. Modified live vaccines are typically administered from 9 weeks of age, with a second dose 3 weeks later. Adult cats should be revaccinated every 1-3 years, depending on the vaccination protocol and manufacturer guidelines - I’d recommend looking at the WSAVA vaccination guidelines for more information on this.

A Chlamydia felis vaccine is also available. Whilst this is not a core vaccine, it is recommended in high-risk patients or environments and in patients with a history of chlamydiosis.

So there you have it - my guide to spotting, managing and nursing patients with so-called cat ‘flu. 

We’ve discussed a fair bit across this episode, so let’s refresh our memories - cat ‘flu isn’t just herpes and calici. It’s a complex of bacterial and viral pathogens that can be present alone or in combination. We commonly see FHV-1, FCV, mycoplasma felis, chlamydia felis or Bordetella bronchiseptica.

Most of the clinical signs these pathogens cause are the same - ulceration, congestion, sneezing, pyrexia, anorexia and dehydration, though there are a few outliers such as limping syndrome.

Care is mostly supportive and is aimed at maintaining comfort, hydration, nutrition and clearing those nasal and ocular secretions, alongside antivirals or antibiotics as needed.

And whilst these patients often need intensive nursing care and strict isolation (which can make delivering that care even more challenging!), they’re also really rewarding to nurse.

Did you enjoy this episode? If so, I’d love to hear what you think. Take a screenshot and tag me on Instagram (@vetinternalmedicinenursing) so I can give you a shout-out and share it with a colleague who’d find it helpful!

Thanks for learning with me this week, and I’ll see you next time!

References and Further Reading

Laura Jones
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67 | 5 key considerations to manage chronic rhinitis confidently as a vet nurse
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65 | Understanding nasal diseases in dogs and cats: how to give great care to your patients as a veterinary nurse