Bella has a terrible cough and some sneezing. We originally thought it was kennel cough but after antibiotics she still had it, (this was about 2 1/2 months ago. Then the vet said it was because she was teething. I took her back to the vet and he said she has allergies that cause the cough so I gave her Periactin and it didn't help. Now I am giving her Clarantine and there has been a minor improvement. Does anyone else give antihistamines to their dog? What has worked for you?