Is FortiFlora necessary when on antibiotics?

My kitty had one of his anal glands rupture and continued to lick it until it was a lesion the size of a quarter.  We didn't notice, because he wasn't sick, ate regularly, etc.  As soon as we visually noticed it, we took him to the vet, where they took his temperature, checked his heart, etc. and pronounced him healthy, other than the lesion.  But, then they gave us antibiotics and insisted he needed FortiFlora to go with the antibiotics.  I'm not a medicine person, my kids have never been on antibiotics and they are in their 20's and I don't like the idea of feeding meds to my cat, that aren't necessary.  I feel you can't trust the vets, as it appears to be all about the money.  So, any advice, experience, and rationale out there?  Thanks!  All comments appreciated.

Probiotics after antibiotics is a good idea since antibiotics mess up the GI system from the destruction of all bacteria including the good ones. However, Fortiflora is not a particularly good probiotic. It has animal digest as the first ingredient which makes it tasty but is a horrible ingredient otherwise. It's a single strain probiotic (e. faecium only). Those of us who provide probiotics to our cats on this site recommend these two human grade probiotics.

The antibiotics don't seem to be messing with his GI system, at least any physically noticeable signs.  Does that make a difference?

I am surprised that there's no stomach upset or loose stool from the antibiotics, but if not, then he probably will be just fine without probiotics.

As there is an infection going on, antibiotics are the best treatment option. For how long does he have to take them?

One of my cats had antibiotics in two courses - first  5 days and then 8 days and he had loose stools that only cleared with about two month (give or take) of probiotics, Entero Chronic and change in diet. I do not support over medicating, but I think that probiotics could do more good than cause harm, or at least this is my experience in using the,. I am actually still upset with my vets for not recommending them for Harley while he was taking antibiotics.

Good News!  Joey is all better and we didn't have to give him the probiotics!  Honestly, I think the cone keeping him from licking his wound is what healed him...Of course, this is my personal opinion.  However, I am a big proponent of our own bodies will heal themselves, which is why my kids have never taken antibiotics and they are very, very healthy.  Now the vets want to throw meds at our animals everytime "they sneeze" just like the doctors do with kids...  So, happy to say, Joey is happy, healthy, his lesion is completely healed and the vet is even willilng to take back the probiotics, since we never opened the package.  Win win!   I appreciate everyone's input.  Thanks!

Glad he is all better!