[anonymously]

I would go by whatever prescription food your vet recommends, I would get the vet’s approval for anything otherwise.

http://www.vetbook.org/wiki/dog/index.php/Silica_uroliths

Silica is a rare urolith which may cause urolithiasis and cystitis.

The role of diet in spontaneously occurring silica urolithiasis has not been determined, although plants are often an abundant source of silica.

These uroliths have been reported in many breeds, mainly purebred dogs[1].

Urolithiasis in middle-aged male dogs is the most common presenting problem[2]. The stones are usually multiple and develop in the bladder and urethra. Silica uroliths are radio-opaque. They frequently, but not always, have a characteristic ‘jack-stone’ appearance.

Identification requires spectrographic analysis and cannot be made with kits for qualitative stone analysis.

When present, urinary tract infections should be eliminated. Diets high in plant proteins should be avoided.