Dog Rocks to lower nitrogen levels in urine. Do they work?

Dog Rocks do nt alter the Ph of the urine in any way. It is not the acidity that kills the grass but high levels of Nitrogen,

A couple possibilities that come to mind about why Rosie's urine is only now killing the grass could be 1. Has her activity level  diminished in some way? Her body will use up nitrogen if she is more active but if she is less active the nitrogen her body does not use will be eliminated in her urine and  feces. 2. Have you fertilized recently with a fertilizer containing nitrogen? If so this could have increased the nitrogen content in the grass (nitrogen in fertilizer combined with nitrogen in urine ) to the point  it is now to concentrated for the grass to deal with and is now burning or killing the grass. 3. Has the weather changed or 4. your watering schedule? If it has been rainy and wet consistently and has just now turned dry the urine being deposited in the grass and getting to the roots is not diluted by the rain / watering and moisture and again has become to concentrated. You can add water to the urine within the first few hours (say 6-7 hours) and it will dilute the urine or nitrogen and salts in the urine. If water is added later than that it is probably to late to help. 5. There are microbes (naturally occurring microbes) in healthy soil. These microbes help break down the nitrogen and salts in the urine so the grass can use it as nutrients instead  of  the damage because of over  concentration. If these microbes have been reduced or eliminated by something (like certain fertilizers)  then this could  make it so the grass can not longer handle the urine. There are products that are sold for eliminating urine damage to grass by adding these microbes to the soil. All of these things have and effect on it. Changing your dogs diet will also affect the urine thus affecting the grass but you already said you have not changed her diet. The type of grass also makes a difference. Of course you would not have changed your grass but for others that read this some grasses are less tolerant to the excess nitrogen and salts and others more tolerant.. There are grass diseases the appear the same as urine spots.

I have been using Dog Rocks for years, they are brilliant. I have 3 dogs, and no brown patches on my lawn.