Short spine syndrome is a very rare congenital defect. Part of awareness Tilly raises is to never breed dogs with short spine syndrome.
Here is more Tilly:

Short spine syndrome is a very rare congenital defect. Part of awareness Tilly raises is to never breed dogs with short spine syndrome.
Here is more Tilly:

They have normal sized organs but all squished together. They generally do not need or get surgery - they are either euthanized because the organ compression and pain are severe or they can live relatively normal lives.
They do not automatically have shorter life expectancy. Quasi the Great (dog with SSS) is 14 years old this year.
It does impair mobility, and the degree to which it does will affect their quality of life.
The bottom line is, we actually don’t know everything there is to know about SSS because it’s so rare.
Source 1: https://petcube.com/blog/short-spine-syndrome-in-dogs/#what-is-the-life-expectancy-of-a-dog-with-short-spine-syndrome
Source 2: https://theconversation.com/jimothy-the-raccoon-has-short-spine-syndrome-but-this-condition-can-affect-dogs-too-288270