Some of Sassy's immediate concerns include shock and blood loss.  These can be addressed in part by placing an intravenous catheter and beginning intravenous fluid administration. 

The next most pressing concern is minimizing further damage to intestines and other abdominal structures as well as infection in the abdomen (otherwise known as peritonitis).  The abdomen is a "sterile" environment and with large sections of her intestines dragging the forest floor there has been a large introduction of foreign material and bacteria that can cause a fatal infection.  This is best addressed by surgery and antibiotics.  However, based on the severity of her injuries, let's look at her long-term prognosis.

Based on the injury to her intestines, it is obvious that a large section will need to be removed.  This will predispose her to a problem known as short bowel syndrome.  In this syndrome, an animal has decreased ability to absorb nutrients from ingested food due to loss or damage of a large section of intestine.  This frequently manifests as diarrhea (often greasy), weight loss and lethargy.