Convenia

I have just Googled this drug, and can see why you are worried. However, if you research any human or animal drugs you will find horror stories. Sometimes headache remedies give headache as a possible side effect! One of my cats was given a single-injection antibiotic, I don't know which one, and she responded quickly. My neighbour who is a vet told me at the time that these have revolutionized cat treatment as giving tablets can be such a problem for some animals and their owners! She did not mention any contra-indications.
I think you have to trust your vet on this and try not to worry, obviously being vigilant for any reaction.
I look forward to hearing that your beloved Trinity is improving in the near future. Give him a tickle from me!

It's forty four years since my ginger cat had a single injection antibiotic which settled a nasty dose of bronchitis - so not such a recent development.

I don't know this drug, but I was worried last year when our vet gave one of our cats a new flea treatment and I later read about cats that had died after using it. However it was very effective and the cat was fine. I think you just have to trust the vet.

Thank you so much for your replies! I know I am a worrier where Trinity is concerned, only he had a rotten start in life, having been run over at 3 months and having a back leg amputated. He also has to have regular steroid jabs, as he is allergic to cereals, grasses, etc. He chose us at the sanctuary at 6 months and is a constant joy! Funny, brave, a real terror and so affectionate! I have lived with dogs most of my life and cats for a large part of it and have loved them all. However, and I'm sure you know the feeling, sometimes one in particular seems to stand out. Trin is one of those! Thanks again.