Please tell me a cat can recover from severe URI

I really do need some reassurance that a cat can recover from a very severe URI (vet thinks both herpes and calici).

My 11 year old, otherwise very healthy cat developped a URI 12 days ago, she's been at the vet's since last Thursday because I couldn't get her to eat/drink anymore (hypersalivation and severe nose congestion).

She's been on antibios from very early on, been on a drip since thursday (BUN a bit high but creat normal, vet feels it is the dehydration that is causing the slightly higher Bun)

She is also on the European Interferon 3 injection programme since last Friday.

I went to see her today and it just breaks my heart - I'm so desperately wanting to see signs of improvement but all I see is my poor little darling so tired and listless, she sleeps on one of my jumpers, but doesn't really react when she sees me.

The vet tech feels there is less nasal discharge, but she now shows a few ulcers on her tongue.

She does manage to keep down most of the liquid food they feed her (they started via nasal tube, but now manage with a syringe).

Does anyone else have any experience of such a bad bout of cat flu and how long can it last before I see some sign of her getting better? 

I feel so scared at the moment.

Thank you for reading this.

When Tyson was 9 mo old he devoloped a horrible case of Calici/Mycoplasma. His symptoms progressed very quickly.

He went from mildly I'll to critical literally overnight. He had several blisters on his nose when I went to bed (no other symptoms) and was critical when I awoke 6 hours later. By the time I got him to the vet (we were there at opening) he had a 106.7 temp, was congested and very lethargic. Within an hour of being at the vet he had gone into acute renal failure due to a mucus plug.

All in all it took about 3 months for him to get completely well.

We used a combination of meds:
Famcyclovir (antiviral)
Doxycycline (antibiotic)
Baytril (antibiotic)
Prednisolone (steroid - for fever)
Buprenex (pain medication)
L-Lysine (immune support)

He also received IV and SubQ fluids, nebulizer treatments and other supportive care.

I want to mention that while Tyson was so sick, his brothers just developed a single ulcer either on their tongue or on the nose. They were treated with Famcyclovir only and recovered within a few days.

On the flip side of Tyson, I lost my 17 year old to a URI back in May after it progressed to his lungs and the infection became resistant to antibiotics. He spent 4 days in oxygen as a last ditch effort to give his body a chance to fight. He was recovering from a boute of pancreatitis and had begun eating well on his own 2 days before his URI symptoms started. So, his immune system was already weak from this.

All this to say that, yes, a cat can recover from a severe URI; but there are a lot of factors individual to the cat.

I really hope you are able to see some improvements with your baby and can take her home soon!

Thank you