Ariel has had a runny nose for a couple days now, and 2 days ago, she started coughing. The day she started coughing, she threw up twice and would barely touch her food. I was so stressed out as we never had this experience with our other dog. And, whatever it was Ariel had, my 2.5 year old dog caught it, and they both started coughing/gagging the same day. We took them both to the vet yesterday morning, and they were both diagnosed with Kennel Cough. Ariel weighed in at 1.9 lbs, which means she lost 0.2 lbs since her last visit 1.5 weeks ago.

Maybe because she wouldn't touch her food before the visit?
Anyway, my question is ... How did she get it? My older dog, Belle, is up to date on all of her vaccinations, and Ariel has not been in contact with any other dogs, except Belle, since we got her. Belle has not been in contact with any other dogs as well. Ariel hasn't been playing outside, as she doesn't have all of her shots. She seemed perfectly fine the first week she was with us - eating, playing, etc. Are there any other ways in which she might have gotten it? The vets gave them both antibiotics, and said that it may take 2 weeks for Ariel to get better. Belle's vet [Belle is at VCA, and Ariel is with Banfield's Puppy Wellness Plan] said it may take 4-16 weeks. The range from the two vets are so different, and am so confused! How long does it usually take for them to overcome this?