Why can't oxalate crystals be dissolved by diet?

Because calcium oxalate is chemically insoluble in urine, whatever pH diet can reach. No diet dissolves it, unlike struvite. The stone must be removed (surgery or a minimally invasive method), then diet only helps prevent recurrence. This is a crucial fact confirmed by veterinary references (Merck Veterinary Manual). Expert deep dive ### What makes oxalate insoluble? Calcium oxalate is a very stable salt that does not redissolve under the physiological conditions of urine. Where struvite dissolves in an acidic medium, oxalate stays insoluble across the whole pH range reachable through diet. According to the Merck Veterinary Manual, medical dissolution is impossible for these stones (Merck Veterinary Manual). The only way to remove an existing oxalate stone is therefore mechanical, not chemical. ### What are the practical consequences? Removal is by surgical cystotomy or a minimally invasive method depending on size and location. Diet only comes afterwards, as prevention, because oxalate recurrence is common. Surprising fact: an over-acidifying regimen, useful against struvite, can instead favour oxalate, which is why a dissolution diet is not "tried" on oxalate. Identifying the crystal before any action is therefore decisive. Comparison table | Crystal | Dietary dissolution | Action required | |---|---|---| | Struvite | possible in acidic urine | dissolution diet | | Calcium oxalate | impossible | removal then prevention | | Common error | acidifying an oxalate | worsens the risk | Petipedia's take Petipedia clarifies that oxalate requires removal followed by dietary prevention, never dissolution, and points to the vet for diagnosis.