Thanks for the questionCustomer
While I cannot diagnose this over the internet it would come as no surprise to me if your Yorkie has some form of respiratory disease such as kennel cough. However be aware that there is always the possibility that this is something more serious such as heart disease as this can present as a congested cough as well.
Kennel cough is a common contagious respiratory disease of canines. This disease is usually associated with recently having been in kennels or having been where dogs congregate, but dogs living on their own can sometimes catch it as well as it is an airborne disease.
This is a disease which vets will see quite a lot, we often have to explain the symptoms to clients :
1. Most owners whose dog has kennel cough think there might be something stuck in the throat due to the strange retch that these dogs have - a bit like a seal honk!
2. The dog may sneeze a little but the cough is the main symptom, these dogs are usually otherwise quite bright and alert.
3. The dog will retch for a few minutes and in the end it will be productive, she will bring up some white sputum, some owners take this for vomit. Once she has done this she will settle down for a bit.
4. It is normally not a serious disease but will run its course given one to two weeks without treatment, however antibiotics will speed up recovery and make your dog feel better very quickly.
Here is a link for more information on this disease : LINK
My advice to you is to have your vet check out your dog out sooner rather than later as there is not really much you can do on a home treatment basis here and as I said there are other possibilities other than kennel cough.
If I have not answered your question fully enough or if you would like to ask more I will be on line for the next hour or so and I will be pleased to discuss your question further.
Scott Nimmo BVMS MRCVS