https://www.backyardchickens.com/threads/more-chick-problems.1119822/Look on the box and see if it contains propylene glycol which may be toxic. Some part of it may and some may not like the cream vs the suppository. I can't exactly remember but if it doesn't contain propylene glycol you should be good to use it. @azygous I believe knows more about it.
You're thinking of Ethylene Glycol, which is anti freeze.