Here is the diet to which I was referring:
A diet suitable for cats and dogs with certain lower urinary tract problems that produce bladder stones or crystals in an acid urine (struvite) consists of: 1.5 lb of cooked ground chuck beef, with the fat retained, 1/4 lb of cooked calf’s liver, one cup cooked rice or mashed potatoes , 1 teaspoon canola oil, 1 teaspoon of phosphorus-free calcium carbonate (crushed calcium lactate or calcium gluconate) or 8 "regular Tums" tablets, one quarter Centrum tablet, 100iu of vitamin E. Fifty-six-84 ml (2-3 ounces) of water can be added during cooking if the cat or dog prefers a moister food. The addition of a taurine tablet and the vitamin E from drug store is advisable in cats of all kinds. Taurine deficiencies can lead to heart problems. Vitamin E (alpha-tocopherol acetate is known to slow the aging process by scavenging free-radicals). Taurine deficiencies can lead to heart problems. Vitamin E (alpha-tocopherol acetate) is known to slow the aging process). Feed approximately 1/4-1/2 lb per ten pounds each day or the amount that maintains optimal body weight. This formula is designed to keep magnesium and phosphorus levels in the food to a minimum. In dogs, bladder stones can sometimes be dissolved using a diet low in protein (not under 15%) which has added salt or potassium chloride to increase water consumption. Most of these dogs need antibiotics as well. In cats with oxalate bladder crystals, the addition of potassium citrate (300mg/day) will sometimes cure the condition. When used in dogs to encourage oxalate crystals to dissolve, the dose is 300mg/10 pounds body weight to a maximum of 1,800mg/day mixed in the food or given as a flavored treat.
This diet will work for oxilate and struvite crystals.
There is not a big problem with keeping the dog on the diet longer but most vets will try the diet for a few months and then opt for the surgery after that time period is over. You COULD keep the dog on the diet for a lifetime if you saw good results.
Since struvite dissolves in acid urine, these diets contain ingredients to keep the urine acidic.
Does this help more? Let me know if there is something that I did not answer! You had a lot of questions!