Hi , I'm James DVM MRCVS and would like to help you with your question
Sorry but lymecycline (the active substance of tetralysal) is not licensed for animals meaning it has not been tested to see if it's harmful or even useful to use on animals . it can even be dangerous.
As such I would strongly recommend against it.
There are many other antibiotics which do work on animals very well and that would be specific to different illness , to that end you must have a vet first see your dog to determine which one would be the best
I hope this helps.
if you wish to discuss the matter further please let me know .
all the best