How long does it take for anitibiotics to start working for kennel cough?

Our 11 week old puppy that we adopted from the animal shelter 9 days ago was diagnosed today with kennel cough & pneumonia. She is coughing, very lethargic & won't eat or drink. The vet gave her an antibiotic in shot form & gave her fluids. He said that she had a guarded prognosis, meaning she might make it, might not. I'm very worried, we've only had her for 9 days, but we are already attached. I'm just wondering if she does pull through, how soon should I start seeing improvement?

There are two types of vaccines for kennel cough. The inject able vaccine takes a while to have an effect, so it is not the best choice if you are in need of rapid protection. The intranasal (inhaled through the nose) vaccine has a quicker effect and is best for more immediate pet contact situations.Kennel cough causes bouts of high pitched, honk-like coughing that keeps both you and your pet awake at night for up to 2 weeks. Onset of this bacterial disease occurs abruptly after contact with infected dogs. "During an infection, dogs generally keep up their normal activity level and don’t feel too sick," There is no cure for kennel cough except time. Thus, prevention is the best way to contend with this disease. "However, kennel cough is self-limiting and will generally clear up in a couple of weeks even without any medication."Owners should be aware of possible secondary infections, which may lead to pneumonia. If pneumonia sets in, antibiotics may be necessary to help clear the infection. At this stage, getting phlegm out of the dog‘s system is key for recovery. Intense coughing can be painful for your pet, so limit activity; the more your dog moves around, the more he will cough.If you have other dogs in the house, they will probably get kennel cough too, but you can take some precautionary measures. Separate everyone, and wash your hands after contact with each dog. Use bleach to clean areas where your sick dog has been."If your pet is coughing for more than 2 or 3 days without signs of improvement, bring your pet to your veterinarian,""Your canine’s cough may not be kennel cough." IF you see any secondary signs, such as depression, lack of appetite, fever, blood in phlegm, or difficulty breathing, bring your pet into your local veterinarian for assessment andtreatment.Most importantly, if your dog does have kennel cough, do not take him into a situation where he will put other dogs at risk of infection. This is very contagious!Most people do not vaccinate their dogs against Kennel Cough unless they are going to be around other dogs, or in a kennel or are a show dog. My parents have a kennel and require all dogs to have their vaccine.