These are my Pomeranians, Sullivan and Duke. They come on a lot of, but not all trail rides with me. If I am going on a longer ride, I will often take turns carrying them in the saddle with me.
These are my Rott./Husky named Bear, and our newest family member - a lab/husky/Mastiff, named Basta. Bear is the greatest trail dog. He comes on all of my longer trail rides. He hates being left in the yard if we ride out with the horses. He is pretty good about moving on past dogs we come across and such (thanks to an e-collar), and he keeps pace very easily with the horses. I do not know yet if Basta will be a good trail dog as he is only just 3 1/2 months old.
Here is Bear, Dez, and I at the end of about 10 miles - a lot of which was at canter pace.