Based on what I can tell from the pictures, the laceration is full thickness meaning you may be able to see organs etc. with a good light and stretching if she tolerated it. Infection, of course, is a risk; However, keeping internal organs moist is key. After a good clean out, I would advocate stitching or stirristrips to close the wound. Even if not sealed perfectly, granulation tissue will eventually seal the gaps. A gauze wrap and chicken sweater will help with supporting and prevention of dehiscence.
A nice long acting antibiotic injection will help keep those infections at bay and then supportive care from there.
Bear in mind, many of our ointments, peroxides, etc. etc. are meant for superficial and external wounds. Ensure anything sprayed into that gaping wound is safe for non-superficial wounds.
Keep us updated and best of luck!