In a previous article, we looked at some of the new drugs that have recently become available for treating FIP in cats. Feline Infectious Peritonitis in cats is traditionally considered a largely incurable and fatal disease. However, we ended with some hope as new advanced antiviral drugs were starting to hit the market. Since, these drugs have become easier for veterinary surgeons treating cats with FIP to acquire, and this author has had one successful (so far) experience in using them. We will now discuss a case of a kitten with FIP that this author has been managing.
Table of contents
Remember, this is just one case!
Please note that all of the following is anecdotal information from a single case, not backed by any peer reviewed evidence, and all errors are the author’s. Nevertheless, this case provides a good example where these drugs gave hope to an otherwise hopeless prognosis, and may be food for thought for owners and vets considering treatment for FIP.
The background
A four-month old female British shorthair kitten presented to us as ‘subdued for two days’. She was still bright and playing, but ‘just not quite right’. While she was off her food, she was still drinking. She had a bloated belly. The owner had sadly had cats with FIP before, and was concerned this cat had FIP as well.
On exam, she was bright and well, with a slight skin tent due to dehydration, and a bloated but comfortable abdomen. Her eyes and gums were icteric (yellow), and her temperature was normal. As we were concerned with her colour, we took bloods. The blood sample was very watery.
Test results
A blood test showed this kitten was anaemic, with a low white blood cell count, low electrolytes and low creatinine and urea (waste products from protein breakdown). Curiously, her protein levels and liver enzymes were normal. We scanned her abdomen using ultrasound which showed a large amount of fluid – this was aspirated and it was bright yellow and clear.
The diagnosis confirmed
We spoke to the owner and advised that based on the current information, wet FIP was likely but not the only possible disease. The owner had previously diagnosed FIP in their cats via testing, but by the time the results were received the cats had died, so the owner was keen to start treatment. We advised that treatment may not work if this was not FIP but we were happy to risk it given the kitten may die if we waited any longer. We thus presumptively diagnosed wet FIP and elected to start treatment.
The treatment plan
It was relatively easy to order the injectable Remdesivir/GS-5734 online from our specialist supplier – it arrived the next day. The drug was 10ml of ready-made liquid in a glass bottle, 10mg/ml. By this time, the kitten had visibly deteriorated, was much less bright, her colour was more yellow, she had a temperature and her anaemia was worsening. A blood transfusion was discussed, but we decided it was not worth the risk to her or the donor.
Doses were taken from the North Downs Specialist Referrals protocol. The first dose of the drug was given to the kitten by the author under the skin (as she had wet FIP with no neurological or ocular signs, we opted for 10mg/kg once daily dose). Since the kitten was still relatively bright, the owner chose to continue treatment at home. Initially, the owner found it difficult to administer at home, as the drug was thick and painful to inject, and the kitten was wriggly. Local anaesthetic cream and sedative tablets were attempted, but the owner eventually managed with assistance from a friend. There were no other side effects, no worsening of the bloated abdomen or uncovering of neurological signs.
After 9 days the owner reported a huge improvement!
The kitten was brighter, more playful, her yellow colour was mostly gone, her temperature was normal and her bloated belly was almost completely back to normal. Progress was rapid and positive, so we elected to switch to oral GS-441524 tablets (from the same supplier, NOT the illegal black-market imports which are untested and whose contents aren’t known). These were also very easy to order and arrived within two days. The tablets were 50mg each, tuna flavoured, came in packs of 10 and could be split in half relatively easy (dose 10-12mg/kg SID without food).
The owner has found the oral tablets much easier to give than injections, and the kitten eats the tablets without complaint (the tuna flavour seems to help!). The owner did note that sometimes the tablets did not break evenly in half, but the dose margins were wide enough that it shouldn’t matter considerably.
Update 22nd November:
Over the past weeks and months, the little kitten with FIP has grown into a big beautiful girl. She has had no symptoms of FIP at all, is eating and drinking well, bright and bouncy and playful. On her last blood test, two weeks after stopping her medication, all parameters were normal. At this point, we can officially consider her ‘cured’ of FIP, though the owner is aware relapses are possible and will keep monitoring her for any signs of this. Though it is still early days, she has made a remarkable recovery from an almost certainly fatal disease.
Where are we now?
At the time of writing, the kitten is on day 27 of her 84 day course, and is doing remarkably well. She is bright, playful, no longer yellow in her gums, and is generally back to her normal self. On a recent blood test, her anaemia was completely gone.
We will be seeing her regularly over the next few weeks, with the plan being to test her blood and assess her around day 84. Should she remain well, not relapse, and have no abnormalities on her blood test, we can consider her successfully cured of presumed FIP. We will update this article once the treatment has ended.
Summary:
- FIP is a viral disease of young cats, causing depression, weight loss, anorexia, fluid-overload, organ damage, brain and eye damage, and death
- Diagnosis is difficult and often not definitive
- Treatment was traditionally only palliative, and FIP was almost always fatal
- New drug options, GS-441524 and Remdesivir/GS-5734, have shown huge promise in successfully treating 80% or more of cats with FIP
- Most information is anecdotal and full-scale scientific studies are scarce
- The drugs were initially difficult to acquire, but are now more widely available within the UK
- They are still prohibitively expensive for most clients
- Drug administration varies depending on the client, cat and disease
- Owners can administer both injectable and oral forms of the drug at home
- Anecdotally, the injections can be difficult to give at home. The drug appears to be painful to administer to some cats
- For those that can afford it, the drugs are potentially the best chance FIP-positive cats will have
- For those that cannot afford the drugs, FIP unfortunately remains a highly fatal disease
Further Reading
Papers:
Other Information:
FIP in cats – is there now hope?
Feline Infectious Peritonitis (FIP) Statement June 2022 – The London Cat Clinic
Successful FIP treatment with remdesivir – RVC
Feline Infectious Peritonitis (FIP) – North Downs Specialist Referrals
Treatment of FIP in cats with subcutaneous remdesivir followed by oral GS-441524 tablets – Zenby Cat
Discussion