How many dogs break their hind legs or back in a year?

It's difficult to provide an exact number for how many dogs break their hind legs or backs in a year as there is no comprehensive, centralized collection of such data. The incidence of these injuries can vary based on several factors, including breed, age, activity level, environment, and other circumstances. Some sources or studies may provide estimates or approximate figures, but the total number is likely influenced by numerous variables and can vary over time.