I have also been giving her benadryl. I tried penicillin injections for about a week but that did not take care of it. When I took her to the vet, he put her on vetmedin for congestive heart failure, also lasix. IOf coiurse, that really didn't do anything for the cough. I took her back and he guessed that it was the trachea thing. I did get it cleared up for a while but then spring came and she seems to have a lot of problems with allergies. She jusyt seems to get worse and worse no mastter what I do. I was wondering if tetracycline would be better to give her than penicillin.