If I remember correctly, melamine was added because it has a high nitrogen signature. And tests for protein present are based on the amount of nitrogen present in a sample. In fact, special formuas for pets with distressed kidneys are usually labelled NFE, such as Purina NF, meaning nitrogen free. In those foods, the proteins are gained from vegetable sources, such as soy, so that the animal still gets protein while giving the kidneys a rest.
When an animal, such as a human or a dog or a cat consumes animal protein, nitrogen is released. Normally, this nitrogen is passed out of the body in urine. When the kidneys are distressed, they can't process the nitrogen so well and it backs up in the system, causing nausea and lethargy.
So, the scam with melamine is to up the nitrogen content, making it look like it's just full of protein.
The way you treat your dog in this life determines your place in heaven. - chukchi proverb
