OK Johelian. What you should do is some searching in the archives. There is a wealth of information there. Discussion and exchange of information is great and that’s why we are all here but is is best to look for the answer before you ask the question. Below you will find some answers to your questions that I cut out of old posts after 5 minutes of searching.
cat food is very high in fat content and is not good for your tegu or any other reptile. There's an awful lot of salts in the cat food, not enough calcium. The D3 content it's way too high to feed dog/cat food can and probably will lead to health problems.
If you knew what I know about the pet food industry and the standards to which they are held, you would know there is no such thing as "high quality" cat food.n/p
Canned foods also have added vitamins and minerals. The problem is that they are TOO digestable. Tegus need some roughage to prevent diarrhea.
A diet with cat food included can lead to renal failure,kidney stones due to high A content, metabolic bone disease, and several other complications.
Now, why do people think adding canned dog, cat, or so-named monitors diets, are a good choice? This I cannot answer, but a little thought would help. Its cheaper, you have to ask yourself why? there are many reasons that these companies can produce and a canned food thats cheaper, and in my mind, none of the reasons are good. I could say that these foods are made up of hormone raised this and that, or whats left over from other food processes, but I will just say, think about it. I could also say, I'am sure these companies do the best they can to make a great product, well, lets think about that too. And be cheap. Lets think about how come it doesn't rot in the can. The companies often say its proven or tested, I have to say, who tested it and what was the test, as far as I know, none of this was ever disigned by monitor keepers, except the turkey diet.