After crate rest is complete a dog needs to have proper total nutrition for the body to rebuild, for the discs and spinal cord to heal and nerves to regenerate. Healing continues on for many weeks and months, it takes a lot of energy and nutrients.

During crate rest after surgery or with conventional treatment, diet changes are not recommended. Figuring out if diarrhea/stomach issues are food or med related is problem during IVDD treatment.

Commercial kibble

Find a dog food that has two animal proteins listed in the first 3 ingredients, preferably the first two, and that is preserved naturally with vitamin C or E (avoid chemicals BHA, BHT, ethoxyquin or propyl gallate). Look for specifically named meats such as chicken, chicken meal, turkey, turkey meal, lamb, lamb meal, eggs.

Avoid beef/chicken/turkey/lamb byproducts, generic meats such as meat meal, fish meal, poultry meal. Avoid any food that contains corn as a first ingredient (ground or otherwise).

Don’t choose a food based on supplements like glucosamine, chondroitin and probiotics as generally they are not included in large enough doses to actually provide a therapeutic effect in kibble. Purchasing a stand-alone supplement product is likely to bring better results.

There are many good choices of kibble or canned food once you know what to look for, pick one that fits your pocketbook. How to grade your dog’s food, some brands rated at end of article.
http://blog.bigdogsporch.com/2006/09/canine-nutrition-101-rate-your-dogs.html

Dog food labels 101. Learn what the ingredients mean:
http://www.dogfoodproject.com

This site rates dog foods available, both kibble and canned:
http://www.dogfoodanalysis.com

More on diets

Confer with your vet before changing prescription diets for dogs with health issues such as heart, liver, alergies, etc.

A list specializing in proper nutrition in a diversity of diets whether commercial, home-cooked or raw. Support for healthy dogs and those with disorders such as liver, skin, heart, etc.
K9Kitchen

Good information regarding food and nutrition:
Dogaware