My dog suffers from allergies and our local veterinarian has prescribed antihistamines, as needed. I also suffer from allergies and my doctor prescribes a decongestant along with my allergy medications, to prevent sinus infections. My question is this; can dogs take decongestants, and if so, which ones do you recommend? She is a 20 mo. old, spayed Newfoundland (mostly); wt.- appox. 95 lbs.