I have not heard back from you and you do appear to be offline.
I have to be away to see some kitty patients of my own just now, but promise to check back on you when I return. In the meantime, I do want to leave my thoughts about Sapphire so far.
As I hinted before, cat flu is an umbrella term for a range of agents that can cause flu like symptoms. The main agents of this group are the viruses known as Herpes and Calicivirus; as well as the bacterial agents, Chlamydophila felis, Bordetella, and occasionally Mycoplasma.
Now I suspect that she has not been tested to pinpoint which is to blame since I can see some treatments that are specific to particular agents (ie L-lysine is a feline herpes treatment & Ronaxan is something we' d use for C. felis or Mycoplasma). And while it looks like a lot of bases are being covered, if she is struggling to get over this and response to treatment, then you might want to discuss diagnostics with her vet. Because if you can pinpoint the agent, you can perhaps target treatment to that agent and discontinue any non-necessary treatments (which perhaps wil make her feel less harrassed and perhaps be more inclined to eat for you).
As I noted before, the Bisolvin doesn't typically affect appetite (unless you are putting it directly into her food an she is a picky kitty. And in that case, you can mix the small dose with water and syringe it separately.). Rather cats that have rhinitis and are congested will often be off their food because they cannot smell it (Feline logic dictates that if they cannot smell it, then it may not be food. And often that means that they will not eat it). Furthermore, with agents like the feline herpes or calicivirus, we can see viral induced oral ulcers. And in those cases, the associated oral discomfort can lead to a reluctance to eat.
In these cases, if congestion is to blame, we can usually get them eating by using smelly wet foods or even warming the food up a bit in the microwave. If the cat has oral ulcers, then sometimes pain relief needs to also be initiated. And if the cat is still resistant, then sometimes we do need to syringe feed them through this, support them with IV fluids (or even IV nutrition at some specialist practices) or even place a feeding tube (This is typically reserved for severe cases). In regards XXXXX XXXXX feeding, we often use Hill's A/D (LINK). This is a critical care diet that is comes as a soft, palatable pate. It is calorically dense, so a little goes a long way nutrition-wise and it's a means of getting calories into them even if we can't get a huge volume of food in. Some cats will eat it (since it is soft) when warmed up. But it can be made into a gruel by adding water, which they can then lap or we can syringe into them.
Alternatively, there is an animal version of Ensure (balanced for animals dietary requirements) called Clinicare Canine/Feline Liquid Diet (LINK). It is actually by the same people who make Ensure, but is formulated to meet out pet's dietary needs. Your vet should be able to order it for you but it is available without a prescription (some pet stores and even Amazon stock it). They also make one specifically for older cats with kidney troubles, and this could be an alternative for an older cat. And again it is a means of providing nutrition for them if we cannot get them to eat properly on their own.
Otherwise, when I had asked after the use of supportive care here, I was referring to some of the non-medicinal supportive measures that we do find useful for cats with these conditions. If she is congested, then we do often find steam treatment can be helpful for them. If she is at home with you, then you can take her in the bathroom while you run a hot shower. The steam will help loosen and clear some of the snot congesting her. You can also use a baby nebulizer, but often cats don't like things held up to their faces. That said, you can alternatively make little ‘steam tents' with her in their carrier, the nebulizer, and a bed sheet covering them both.
If she is building up mucus that the steam isn't shifting, use a cotton ball moistened with warm water to wipe away crust and mucus. Use saline nasal drops (like Ocean Mist) but not anything medicated. Tilt the head back and drop two to three drops in one nostril. Cats hate this, but it helps. After the drops go down, you can let the head up and wipe away any discharge that gets loosened. Then repeat with the other nostril.
Overall, anorexia is not an unusual feature of cat flu. Often it is secondary to congestion or to oral ulcer induced discomfort. But no matter the cause, we do have to persevere with treatment against the flu agent, potentially modify treatment to relieve congestion or pain, and also maintain nutritional support (even if it means syringe feedings, IV fluids or a feeding tube). So, I would consider any of the above you are not already doing. And if Sapphire is struggling with her aged immune system to fight this agent, then do consider taking steps to identify which cat flu agent is causing her troubles to then target her treatment effectively.
I hope this information is helpful.
Please do let me know if you have any further questions.
If you have no further questions, feedback is always appreciated.
All the best,
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