Complex sentence: Degenerative disc disease can also occur in other mammals besides humans; it is a common problem in several dog variants and attempts to remove this disease from dog populations have lead to several crosses, such as the Chiweenie.
Split into simpler sentences: Degenerative disc disease can also occur in other mammals besides humans. It is a common problem in several dog variants and attempts to remove this disease from dog populations have led to several crosses, such as the Chiweenie.