Hello Sue, I'm Dr. Deb and will do my best to help you today.
It's certainly possible that the kitten gave Monty the Feline Flu (the most likely scenario) but it's also possible that it was a pre-existing condition since he was also a foster cat.
Cats who are exposed to the herpes virus can retain this virus in their bodies for their entire lives; it can remain dormant until triggered to emerge. There are a lot of triggers such as stress (although it's not always easy to identify what might stress a cat!), changes in weather, changes in food, certain drugs, trips to the vets, etc.
The underlying cause of Monty's symptoms now are somewhat irrelevant but I just thought I would point out the slight possibility that the kitten wasn't at fault for making him sick....although I'm rarely a big fan of coincidence!!
When cats develop feline flu, we typically don't dispense oral antibiotics unless there's a green or yellow color to any nasal or ocular discharge. Since these are primarily viruses, they have to run their course, similar to a cold in a human, which is usually around 7-10 days.
But, I do have a few suggestions which may help Monty feel better.
1. Use warm water to clean the eyes and nose of any discharge that builds up. Over the counter artificial tears can be used to flush out the eyes if they become affected.
2. Nasal decongestant drops can be helpful although many cats don’t like them very much as you can imagine. They should only be used for three days in a row, with one drop in each nostril; otherwise what’s known as a rebound effect may occur
a. Pediatric otrivin=0.05% xylometazoline
b. “Little Noses" Decongestant Nose Drops with phenylephrine hydrochloride
c. Afrin (oxymetazoline)
d. "Little Noses" Saline Spray/Drops non medicated which can be used more than three days in a row.
3. Continue to provide humdity as you have been since this can help loosen up secretions.
4. There are no safe over the counter cold remedies that we might take but antihistamines can help some cats:
Benadryl at a dose of 1/2 of a 25 mg tablet given twice daily or
Chlorpheniramine at a dose of 2-4 mgtwice a day or
Claritin at a dose of 2.5-5 mg twice or
Zyrtec 5 mg/cat once or twice a day
It is important to ensure that the formulations used contain ONLY the antihistamine and are not combination products (e.g. Claritin-D contains pseudoephedrine, which could cause very significant adverse effects in a cats.
Sedation is a common side effect with these kinds of drugs.
I hope this helps and that he's feeling better soon. Deb