Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern for your farm cats.
It sounds as if they have developed an upper respiratory infection (aka Feline Flu) since this condition can be contagious between cats and often causes the symptoms you mention.
The Feline Flu is similar to colds in humans in that they are usually secondary to viruses:Herpes or Calici viruses are the two most common causes of this condition in a cat.
Secondary bacterial infections can develop (the nasal and/or eye discharge can be green or yellowish in color) and when this happens, antibiotics are usually dispensed.
These cats can often run low grade fevers and not feel like eating or drinking although this isn't true for all patients.
These episodes typically last anywhere from 10-14 days but when multiple cats are involved, they can continue to pass the infection back and forth although herpes viruses can remain in the body for years (and continue to cause low grade symptoms).
My suggestions for them would be as follows (since it may not be practical to have them all seen by a vet).
1. Continue to 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.
2. Nasal decongestant drops can be helpful although many cats don’t like them very much as you can imagine. The medicated ones (a-c below) 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. This is one reason why I prefer "d":
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. L-lysine can help with any eye issues. Herpes viruses can settle in the eyes and cause low grade chronic issues there as well as acute problems. This supplement would be given daily (250 mg) but doubled if there is a flareup (500 mg) later on. The feline product is available on the internet as either a chewable treat or a paste; the human version comes in a capsule and the contents can be sprinkled on wet food and given this way as another option.
4. Probiotics such as Forti Flora have been shown to help many of these cats with the Feline Flu; probiotics aren’t just useful for gastrointestinal issues. This particular product is available as a powder which is sprinkled on the food every day and can be purchased at many pet/grain stores or online.
I hope this helps to provide options for you to consider. Deb