Thank you for the additional information.
I am sorry to hear about the cough that Lucy has developed in the last 10 days. The most common causes of a cough that occurs more often when she is excited, exercises, or eats are:
- Heart disease
such as a weak valve or valvular disease
- A collapsing trachea which is the most common cause in smaller breed dogs - this is basically where the trachea is made up of a very flimsy cartilage that folds or collapses when she is breathing faster
- Allergic bronchitis
- Mild pneumonia from bacteria or fungal infections
- Kennel Cough
on an infection of the trachea/bronchi
At this time the best way to get an exact diagnosis would be to take Lucy to your vet to have an exam performed. Your vet will most likely also want to take an x-ray to get a better diagnosis of where the cough is coming from. I do not think that you need to rush to the vet tonight unless Lucy starts to really have labored breathing or becomes very lethargic, but I would consider taking her to the vet within the next couple of days if possible.
Your vet will be able to give her some medications to stop or reduce the cough based on the exact cause. For now if you wanted to give her something you can use some Robitussin DM
very safely. The dose for dogs is 1/4 of a teaspoon for every 10 pounds every 8 hours. This can cause some drowsiness but is otherwise very safe.
Overall a collapsing trachea would be the most likely cause since she is a smaller breed dog. Most of the time getting her to calm down and relax is all you need to do to help her though some dogs do require cough suppressants to make sure that they do not have any trouble breathing. Here is a very good website that describes this disorder in more detail for you:
Hope this helps to answer your question - if not or if you have any more questions please feel free to reply by clicking on the "reply to" button. Thank you for your question!