Complex sentence: The post-operation dogs were assigned a pain score eight times within a 72 hour time-frame, and thought significantly lower pain scores were found in the treatment group after 36 hours, they did not differ from the control group at any other time.
Split into simpler sentences: The post-operation dogs were assigned a pain score eight times within a 72-hour time-frame. Though significantly lower pain scores were found in the treatment group after 36 hours, they did not differ from the control group at any other time.