Calcium oxalate in the cat: how to prevent recurrence
10-year-old neutered cat that had cystoliths removed; analysis shows 100% calcium oxalate. For years he has eaten an acidifying dry food to 'prevent crystals'. Ionised calcium is normal.
Which preventive measure is most appropriate?
chevron_right Show answer and explanation
A. Increase water intake with wet food to dilute the urine and stop using acidifying diets
Correct. Calcium oxalate does not dissolve with diet; prevention relies on diluting the urine (low specific gravity) and avoiding excessive acidification, which increases urinary calcium excretion.
B. A struvite dissolution diet, which will also dissolve any remaining oxalate
No diet dissolves calcium oxalate. Struvite dissolution diets are acidifying and may promote oxalate formation.
C. Restrict dietary calcium as much as possible
Severe calcium restriction leaves more free oxalate in the gut, which is absorbed and excreted in urine. It is not recommended.
D. Supplement with vitamin C to acidify the urine
Vitamin C is partly metabolised to oxalate and increases urinary oxalate excretion. It is contraindicated in cats with oxalate uroliths.
lightbulb Key takeaway
In cats with calcium oxalate: more water, no excessive acidification, measure ionised calcium (idiopathic hypercalcaemia) and monitor with periodic radiographs to remove small stones before they grow.
Test yourself with 10 random questions
Urinary system · 100 questions, a different test every time
Related questions
Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.