If he is vomiting and bringing up food or yellow stomach liquid it may be one of the foods you are feeding. Don't give him any food for 6 hours, he can have water. After that time start him back on cooked chicken, chicken baby food, or lunch meat. If no vomiting after 24 resume a new bag of your regular food. If you feed canned food, watch for one variety causing vomiting.

If he is gagging up nothing or white phlegm, he is not vomiting, he has a flare up of the respiratory virus and is gagging from an irritated throat.

The cats do not have to "catch" the virus, it's in their system. Although the virus is contagious, I would assume your other cats immune systems will keep them protected. If not, the following applies to them also.

The upper respiratory virus in cats is caused by a herpes virus (not contagious to humans). Every cat has been infected with the virus as a kitten. Most cats have been vaccinated for this virus with their routine vaccinations. The virus never goes away; it just goes dormant in the body. During periods when immunity goes down, the virus can flare up and show signs of infection somewhere in the body.

Spring and fall seems to be a common season for these viral flare ups, just like the human flu season. Stress events frequently lower immune resistance and can bring on a flare up of the virus. In mature, vaccinated cats the signs tend to be mild and self-limiting.

As long as your cat continues to eat and has no colored (yellow/green) discharges from its nose or eyes, the signs you are seeing should resolve in 5-7 days.

If your cat stops eating, develops more significant discharges, or if the signs worsen or persist, call your veterinarian for an examination.

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