My Small Yorkie Is Trembling And Panting, What Is Wrong?

My 19 month old border collie, female, ate about an hour and a half ago.   Same food she has been using for several weeks.   We discovered her about an hour ago, trembling and panting.   She seems to want to be in a dark quiet place.   She has never done this before.   We live in argentina, rural, and can not get a vet at this hour.   It is winter here but not very cold at the moment.   This seems to have happened suddenly.

Both trembling and panting can be normal in dogs after the exercise or when they are excited. Only excessive panting is not good sign. Shaking or trembling and panting can be due to pain. Following are some common causes of this condition in dogs.

1. Pain
2. Anxiety
3. Excitement
4. Fever
5. Fear
6. Dehydration
7. Heartworm
8. Heart diseases
   
9. Anemia
10. Hypothyroidism
11. Poisoning

Treatment depends upon underlying cause. So, take your dog to vet.