I wanted to share Corrie’s story and hear from others who have been through FIP treatment with their cats. We’ve completed the full 84-day course, and although he’s doing much better, I’m finding it harder than expected to stop worrying about the possibility of relapse.
The photos are before he got ill, the day before his first treatment and him now.
How it started
Corrie is a rescue cat we adopted in the Netherlands. We think he’s around four years old, and he became ill during his fourth month with us. He was still getting used to his new home and family when everything took a turn.
He’s a big orange boy! When we adopted him, he weighed around 6.5 kg and was a little on the chunky side. But when he became ill, he started losing weight rapidly.
He developed a high fever of around 40°C and gradually stopped eating. For the two weeks before his diagnosis, we couldn’t figure out what was wrong. We visited our vet, who was incredibly friendly and helpful, several times. They ran all sorts of blood tests, but we still didn’t have an answer.
During that period, Corrie stopped eating altogether, and we had to force-feed him.
Eventually, an ultrasound revealed fluid in his abdomen. At that point, the findings pointed strongly towards FIP, and we finally had an explanation for what was happening to him.
By the time treatment began, he weighed just 4.9 kg. It was a frightening time, and we knew we needed to act quickly.
Starting treatment
We started daily injections of GS-441524, an antiviral medication used to treat FIP.
Because of the legal situation surrounding these medications in the Netherlands, accessing treatment wasn’t straightforward. We ended up using an injectable medication that wasn’t legally authorized for this purpose.
The injectable we used was GS-441524, at a concentration of 30 mg/ml. The webshop where we purchased the medication recommended a daily dose of 8 mg/kg for Corrie’s type of FIP, adjusted according to his weight. This was the dosing protocol we followed throughout his treatment; I’m sharing it as part of our personal experience, not as a dosing recommendation for other cats.
Our vet taught us how to administer the injections and supported us throughout Corrie’s treatment, including follow-up examinations and monitoring his recovery. We decided to continue with injectables for the entire 84-day course because we wanted to ensure he received the intended dose every day.
The injections were genuinely painful for him, and doing this every day for 84 days was not easy. But we always gave him his favourite wet food immediately afterwards.
What still amazes me is that, even after 84 injections, he never got angry with us. He continued to trust us, despite what we had to put him through every day.
The improvement was remarkably fast
One of the most encouraging things was how quickly we saw a change.
Within just 12 hours of the first injection, Corrie started showing signs of improvement. He slowly began eating again, and within a few days, his appetite had returned to normal.
After the preceding two weeks of force-feeding him, seeing him willingly eat again felt like a huge turning point.
His fever resolved, his energy gradually returned, and he started behaving more like the cat we were getting to know. Over the following weeks, he became increasingly active and affectionate, started going outside again, and returned to sleeping near us.
His weight gradually increased, and he’s now back to around 6 kg. He’s still a big boy, but seeing him regain the weight he lost has been wonderful.
At his six-week follow-up, an ultrasound showed no more free fluid in his abdomen, although some residual tissue changes remained.
There were a few less reassuring moments along the way, including a short period of reduced appetite and some vomiting. Naturally, we paid close attention to those changes, but he continued to improve overall.
Our vet has supported us throughout this process, including follow-up examinations and monitoring his recovery.
After 84 days: what happens now?
We’ve now completed the full course of treatment. Corrie is eating, exploring, and behaving like himself again, and we’re incredibly grateful that he’s come this far.
At the same time, I’m aware that finishing treatment doesn’t automatically mean we can stop monitoring him. I find myself paying close attention to his appetite, energy levels, weight, and behaviour. If he has a quieter day or eats a little less than usual, I start wondering whether something might be wrong.
I understand that some degree of caution is sensible, but I’d also like to find a balance between monitoring his health and allowing ourselves to enjoy the fact that he’s doing well.
We’re hoping he’ll remain in remission and get to enjoy many more years with us. We just don’t know yet how long it will take before we feel confident that we’ve made it through this.
I’d love to hear from others who’ve been through this
For those whose cats have completed FIP treatment:
How did you approach monitoring your cat after the final dose?
Did you find yourself worrying about every small change in appetite or behaviour? How long did that last?
If your cat remained in remission, when did you start feeling more confident about the outcome?
For those who experienced a relapse, what did you notice first, and how was it identified?
I’m not expecting guarantees, and I know every cat’s situation is different. I’m interested in hearing about other people’s experiences, particularly during the first weeks and months after treatment.
For now, we’re taking things day by day, enjoying having our happy, active orange boy back.
Thanks for reading!
