Feline clinical virology special collection

In the November open access episode of Chattering With iCatCare, Yaiza Gómez-Mejías is joined by Professor Margaret Hosie to explore a landmark JFMS special collection on feline virology, offering practical, evidence-based guidance for managing viral infections when gold-standard diagnostics or treatments are out of reach.

They discuss why an FIV diagnosis should never be treated as an automatic death sentence, how to navigate client queries around off-label antivirals for feline leukaemia virus, and unexpected dietary and lifestyle risks linked to emerging avian influenza outbreaks. Margaret also outlines accessible, cost-effective diagnostic pathways for suspected FIP, practical alternatives when first-line antivirals are unavailable, and the key clinical biomarkers clinicians can track to evaluate whether treatment courses can be safely shortened.

For further reading material please visit:

Feline clinical virology

ABCD FIP diagnostic tool

Machine learning for effusive FIP:
Dunbar DE, Babayan SA, Krumrie S, Rennie S, Waugh EM, Hosie MJ, Weir W. Applying Supervised Machine Learning to Effusion Analysis for the Diagnosis of Feline Infectious Peritonitis. Bioengineering (Basel). 2026 Jan 23;13(2):127. doi: 10.3390/bioengineering13020127. PMID: 41749667; PMCID: PMC12937978.

Machine learning for non-effusive FIP:
Dunbar D, Babayan SA, Krumrie S, Haining H, Hosie MJ, Weir W. Assessing the feasibility of applying machine learning to diagnosing non-effusive feline infectious peritonitis. Sci Rep. 2024 Jan 30;14(1):2517. doi: 10.1038/s41598-024-52577-4. PMID: 38291072; PMCID: PMC10827733.

Update on Treatment of Feline Infectious Peritonitis: European Advisory Board on Cat Diseases (ABCD) Guidelines. Tasker S, Spiri AM, Hartmann K, Addie DD, Belák S, Bergmann M, Egberink H, Frymus T, Hofmann-Lehmann R, Marsilio F, Pennisi MG, Thiry E, Truyen U, Boucraut-Baralon C, Möstl K, Hosie MJ. Viruses. 2026 Apr 9;18(4):452. doi: 10.3390/v18040452. PMID: 42043241; PMCID: PMC13120026

Host:

Yaiza Gómez-Mejías, LdaVet MANZCVS (Medicine of Cats), RCVS CertAP (Feline Medicine), iCatCare Veterinary Community Co-ordinator

Speaker:

Margaret Hosie, BSc, BVM&S, PhD, MRCVS, Professor of Comparative Virology at the University of Glasgow Centre for Virus Research

Creators and Guests

Host

Yaiza Gomez-Mejias

Veterinary Community Co-ordinator @ International Cat Care

What is Chattering with iCatCare?

Welcome to Chattering With iCatCare, the official monthly podcast of International Cat Care, hosted by Yaiza Gomez-Mejias (Veterinary Community Co-ordinator). Each month, we chatter about cats and cat-friendly practices with industry experts and contributors to The Journal of Feline Medicine and Surgery. If you would like access to our members episodes become an iCatCare Veterinary Society Member and get in touch.

[00:00:00] Yaiza Gomez: Clinicians frequently encounter barriers to diagnosing and treating viral diseases in cats. On the other hand, we often need to include these viral diseases in our differentials, especially when cats present for vague signs, which happens frequently. In this episode, professor Margaret Hosie will discuss how a new JFMS article series about virology can support evidence-based management, even when gold standard diagnostics or treatments are out of reach.

So thank you, Margaret, for joining us today. And to start with, is there something new and clinically relevant about feline immunodeficiency that deserves mention?

[00:00:43] Margaret Hosie: I think in this special collection, we have a very nice review article from Mary Nehring and her colleagues at Colorado and it's reviewing past publications on feline immunodeficiency virus.

What's the most important thing to know about FIV-ers? The [00:01:00] variable outcomes. Some cats can live a normal, healthy lifespan, but yet others develop lymphomas, for example, and can progress to clinically very significant diseases, so I think it's challenging for practitioners, but I would probably highlight a publication actually from 2015 by Pawel Beczkowski. He monitored the group of cats with FIV that were housed in single cat household, and they were very well looked after, had very frequent veterinary examinations and those cats, during the course of his three year PhD, there was only one death and that was due to cardiomyopathy, so unrelated to the FIV infection. But in contrast, in a second household, it was a lady who had an FIV infected cat herself, and she made it known that she was looking for another FIV infected cat and as a consequence, she ended up [00:02:00] taking in innumerable cats. Pawel followed over 30 from her household. So the cats were well looked after, but they didn't receive the frequent veterinary care and obviously there was quite a volume of cats living together so there was a stress situation potentially, and many of those cats died, and that gave him the opportunity to look at how the virus changed in the cats that stayed healthy and those that progressed to disease.

For now, I think the take home message for vets in practice is to advise owners of FIV infected cats that a positive diagnosis should not be a death sentence, but cats should be cared for, maybe more frequent checkups at the vet, maybe every six months, for example, and that way any secondary infections can be treated immediately, [00:03:00] and then they have a much better prognosis.

[00:03:03] Yaiza Gomez: Thank you. The longitudinal study by Morais de Almeida on raltegravir in leukemia progressive cats showed reductions in viraemia and clinical stabilisation, which is awesome, but no definitive survival benefit.

Based on this information, how do you think general practitioners can frame conversations about off label antivirals? So owners understand realistic outcomes, especially given the financial costs.

[00:03:31] Margaret Hosie: It must be very challenging for people in practice because the public have access to the internet, of course, and they're going to come up with these drugs that have perhaps showed some kind of efficacy, maybe in vitro, but not necessarily in vivo.

And so I should really declare my, an interest here, as my involvement in the European Advisory Board on cat diseases and our mission is to [00:04:00] translate research findings into useful guidelines and fact sheets to guide practitioners to diagnose, treat and prevent infectious diseases. Papers such as that study on raltegravir have been scrutinised by the advisory board and we have discussed how to frame this in their guideline on FELV, and we would say that we would not recommend its use because there's not got proven efficacy. I think it's unreasonable to expect practitioners to follow every single study that's conducted. It's better for us to synthesise the evidence and then present the evidence and the recommendation to the practitioners.

[00:04:45] Yaiza Gomez: That's so true, thank you so much.

Emerging around 2021, this highly pathogenic avian influenza seems to have reached nearly every continent.

What advice should we give to cat owners [00:05:00] regarding the outdoor access based on what the articles say?

[00:05:04] Margaret Hosie: I think where there's a known outbreak in wild birds in an area, it is advisable for cats not to have unlimited outdoor access and certainly we want to avoid cats scavenging on dead birds because obviously that's where they become infected. On the other hand, we have to weigh up the benefits to the cat of getting outdoors. I think it would be unreasonable to say keep cats indoors if they're used to going outside, but where possible limit outdoor access and access to dead birds. And of course, that automatically, I would be very strongly advised not to feed raw food diets because the raw poultry diets have been associated with transmission of infection to cats.

And in the recent H5N1 outbreak in the US that affected the dairy [00:06:00] cattle, we saw that cats on farms that were ingesting the unpasteurised milk, they were also infected, and the neurological signs were very severe and cats died from the H5N1 influenza.

Avoid raw poultry, unpasteurised milk, and limit outdoor access and predation on dead birds in areas where there's known to be high prevalence of avian influenza.

[00:06:30] Yaiza Gomez: Those are very useful things when we screen for exposure risks, thank you so much. And what's your view on how things have evolved around this influenza virus? Because it doesn't seem to have had a huge impact where I live, perhaps because I practice in an urban area. You must have an overall view of this topic that I'm interested in listening about.

[00:06:52] Margaret Hosie: I think it's really interesting that we keep studying that the occurrence of exposure of cats to [00:07:00] influenza because there's a nice study by the Dutch group which looked at cats with outdoor access and cats there are kept indoors and they saw by looking serologically that cats with outdoor access were more likely to have seroconverted i.e., being exposed to the H5N1 avian viruses, whereas the indoor cats were susceptible to the human pandemic strains, so the H1N1. And so of course this means that potentially cats are exposed to both. They could act as the mixing vessels for new recombinants. You know, I'm very much an advocate of one health and I think it's important that we have such close contact with our pet cats that we must understand the exposure rates to all the different influenza virus types.

[00:07:54] Yaiza Gomez: Let's start with FIP, which is a very trendy topic now that we've got a treatment for it. [00:08:00] Still achieving a definitive FIP diagnosis via histopathology is often financially or clinically unfeasible. What is, from your point of view, the most cost effective diagnostic combination for general practitioners to build confidence before starting therapy?

[00:08:18] Margaret Hosie: Well, again, I would probably direct listeners to the ABCD FIP diagnostic tool, which I think is the result of many discussions, as you can imagine. But we have got a good consensus and we've got this rather nice flow chart which guides practitioners through all the different sampling, starting off with signalment history and the clinical examination of course, and then routine biochemistry, haematology, and effusion analysis if it's present.

But because there were so many different factors taken into account when our clinical [00:09:00] pathologists and people in our veterinary diagnostic lab report out sample testing. We have a PhD student, Dawn Dunbar, who's been working on using machine learning to see whether it's possible to automate to an extent and pulling in all the different data that's available from cats that are being tested, and she published earlier this year on how effective machine learning could be applied to diagnosing effusive FIP and more recently, she's looked at non effusive FIP, and several parameters kind of pulled out as having the most influence on the final diagnosis, and so those are relatively accessible for practitioners.

For example, a high coronavirus titer, a high AGP, so that's alpha one glycoprotein, that's a very good marker. [00:10:00] Hyperglobulinemia, so these are untied total proteins. These are all things that are relatively accessible because we appreciate that it's not always going to be possible to get a good biopsy for doing immunohistochemistry, which is the kind of gold standard.

[00:10:16] Yaiza Gomez: Brilliant. Yeah and these multiplex fluorescent immunocytochemistry, is this something different to the immunochemistry we did before?

[00:10:26] Margaret Hosie: Yes, I think it is. It's a new fancy method, but yeah, it'll be very expensive, I imagine and it's not something that every lab will be able to offer immediately.

[00:10:37] Yaiza Gomez: According to one of the articles, oral remdesivir is non-inferior to oral GS for achieving short term remission in non-effusive FIP. How do you think investigating multiple oral drugs help us navigate the availability or the lack of availability of certain drugs or the financial constraints that we've been experiencing when treating [00:11:00] FIP?

[00:11:00] Margaret Hosie: I think in the UK we've been incredibly fortunate that both the compounding pharmacy have been able to supply with GS-441524, which I'll just call GS from now on, because that is the drug of choice for treatment, can be given orally, but because that's not available in all countries, it's been necessary to look at alternatives for what people are able to access.

And so this paper was important to show that you, generally  remdesivir is being given as an injection where cats can't tolerate oral medication, and so the fact that oral  remdesivir is giving reasonable results is good in countries where it's not possible to access the GS.

I don't know that the costs of GS versus  remdesivir, but I think they're all quite expensive and that leads on to studies that are showing that shorter courses can be as [00:12:00] effective. Originally it was 84 days. It was suggested that that can be cut down to 42 days now, but so that, that will cut the cost.

[00:12:11] Yaiza Gomez: That's really good news. One of the articles by Kamiyoshi showing that there's some potential helpful use of the serum amyloid A and alpha 1 acid glycoprotein, which allowed a large percentage of cats to stop treatment earlier at 54 days without relapsing. So what's your take on the conclusions of this study?

[00:12:34] Margaret Hosie: Well, I think that's the shortest duration study that's very consistent with a previous publication by Katrin Hartmann that showed that 42 days courses could be effective. But I think what this article shows is that it's good to monitor your  serum amyloid A and alpha 1 acid  glycoprotein, and perhaps you could also measure viral loads to [00:13:00] decide when you can stop treatment because you want to have as short a treatment period as possible to avoid any adverse effects.

[00:13:10] Yaiza Gomez: Is this new treatment of FIP the most exciting thing that has happened since you started your career as a researcher in cats?

[00:13:18] Margaret Hosie: It's been incredible. It has been a total game changer. It's very exciting time, very, yeah.

[00:13:25] Yaiza Gomez: Wow. And how do you feel about this series of articles?

[00:13:28] Margaret Hosie: I think I've just always had an interest and a passion for feline viruses.

When this opportunity came up, I couldn't say no to have a special collection on feline viruses. Yeah, it's just been great and it's lovely to see the work from all over the world together in this special collection.

[00:13:47] Yaiza Gomez: Well, I think that brings us to the end of a fantastic conversation. A huge thank you to Professor Margaret Hosie for sharing her expertise and practical insight with us.

And if you'd like to dive deeper into the research [00:14:00] we've discussed today, be sure to check out the special collection on Feline Viral Infectious in the Journal of Feline Medicine and Surgery. Thank you for listening, and thank you for everything you do for feline health. We'll see you on the next episode.