overdose of antibiotics in senior cat?

Question
Our 15 year old tabby was seen at a Vet ER on Sunday, June 3, with an abcess - suspected anal sac. She was given a convenia injection .33cc and put on Orbax daily. The wound was debrided and sutured with a guaze drain. When we took her to her regular vet, he was concerned with the initial surgery - the drain had been stitched to the tissues, hence it drained nothing. Upon opening the wound, there was serious necrotic tissue, so a reconstruction was necessary. He administered another Convenia injection .34cc, gave her a penicillin injeciton, and a Gentocin injection. Both vets gave her Buprenex for pain. Not that it really matters, but we paid $1000 at the ER vet and only $250. at our regular vet (including overnight observation) - we love them and they love cats!
My concern is, has she been overmedicated and if so, is there anything we can do now? She is very lethargic, but with spurts of great energy (jumping up and down off the bed or running up and down stairs). She is eating and drinking regularly, and eliminating daily - but her BMs are runny and green. My biggest worries are the two Convenia injections 4 days apart and the side effects I read on Gentocin. We are still giving her Orbax .9cc everyday. Will call the vet on Monday. Thanks Jessica. Her blood work looked great, despite her age - so far, she has just had some pancreatitis and small bowel malabsorption, but nothing else. On M/D diet and B-12 shots. We have her off the E-collar for now because she is not licking the wound - but she is happy to be grooming her face and feet!

Answer
Hi Connie,

The poor little dear!

I don't think you have a lot to worry about in terms of overdosing. Most cats are given a benzopen (injectable penicillin) shot before surgery, and if an infection is present, they will be sent home with another antibiotic. It's preferred to wait 10 days between Convenia injections, but because germ-fighting activity does peak when administered and then it begins to drop off, and your cat is battling such a serious infection, your vet may have wanted to repeat it sooner.

I'm not exactly sure why all the medications were necessary. My vets avoid gentamicin as an injectable because of the possible side effects. The Convenia really had all your bases covered. So I think that would be a question for the vet. As for the Orbax, this is a very potent antibiotic usually reserved for life-threatening infections. But not as many germs are susceptible as are to Convenia. I suspect this was given so the Convenia and Orbax could make up for each other's weak spots.

I'm thinking that your kitty's down time may have to do with the Buprenex. This causes drowsiness. But if you think she's doing poorly for another reason, certainly get her in. The diarrhea could be caused by any of the antibiotics. A tablespoon of plain yogurt each day, if she likes it, may help.

Good luck!
Jessica