Diet and magnesium

When Kaydees behavior began to worry me (see earlier blog), I noticed a product called 'stress less' on the market. The website claims: 'All animals need to have the correct balance of calcium and magnesium. When a dog is highly strung or becomes stressed, anxious, nervous or excited, they burn off magnesium. This allows calcium to overload muscle and nerve cells and replicates the rise of adrenaline. This can cause erratic behaviour, aggressiveness and/or tightening of muscles.' (Muscle cramps in humans have been successfully treated with magnesium compounds). The vet added a magnesium assay to Kaydees blood tests, and this indicated that she was a little low in magnesium. So I gave her the stress less product at the recommended level. A month later the test was repeated, and the magnesium levels were only slightly higher. My vet did not seem terribly convinced by any magnesium level theory. I stopped supplementing Kaydee, and this happened to coincide with the time she went lame again. Her behavior also deteriorated. Possibly coincidendal, and possibly her behavior is associated with pain and nothing to do with magnesium. My vet has suggested putting K on a veterinary diet to exclude anything that might cause digestive aggrevation, which in turn might cause reduced absorbtion, which might lead to low magnesium levels. It is likely to be much more complicated, as all the electrolytes need to be balanced for the biochemistry to work properly, however I remember from A level biology that a balance of calcium and magnesium ions is required for muscle contraction and relaxation. I have tried to find a canine nutritionist for some knowledgable insight into this. I did get the following useful information: 'Unsuitable diets can cause a build-up of waste toxins which accumulate in the body and build-up over a period of time, eventually beginning to interfere with the proper function of the body’s system. As the body tries to maintain a balance the toxins are eliminated in many forms, including muscle cramps.' Also: 'Muscle glycogen stores supply approximately 70% of the energy required for exercise with fats providing the rest. High carbohydrate levels in a diet maximum muscle glycogen reserves which may reduce the occurrence of the muscle cramps as well.' And finally: 'We do recommend cutting out all treats and tit-bits however adding cooked green vegetables, potatoes and boiled eggs will increase the magnesium intake.' The path I have decided on is to change her diet, to try and learn enough to make informed choices to make her diet as nutritionally balanced as I can, and one that contains as few other added chemicals as possible (and one that I can keep her on long term, including affording it, so the prescription diet is out!) I have started investigating barf, have started adding raw and home prepared foods to her diet, and will probably do half raw food and half a premium quality organic pre-prepared dog food. At the moment she is still getting the extra magnesium supplements. My other dogs have been fine on a premium kibble for years, but can I do better?
All comments welcome!