Sleeping bag for a dog

[Wok de dog]

For an upcoming long distance walk I have purchased a tarp, bivvy bag and plan to wild camp with my dog.
I bought an alpkit extra big bivvy to accommodate my dog, a small terrier but he struggled to fit in my sleeping bag too.
Has anyone else had this problem? Any advice on a bigger sleeping bag or does a dog sized one exist? Maybe I will need to butcher a cheap bag and stitch it for him.

[tall-story]

I just about choked on my coffee reading this its a dog it will be more than happy out side any sleeping bag, and more to the point how on earth do you sleep with a dog scratchin ticks etc all nite