Oxalates are anti-nutrients found in certain plant foods that bind to calcium in the digestive tract, forming insoluble compounds that cannot be absorbed. This reduces the bioavailability of dietary calcium and, in susceptible dogs, can contribute to calcium oxalate bladder stones — one of the most common types of urinary stones in dogs. High-oxalate foods include spinach, Swiss chard, and beet greens.
Spinach contains roughly 750–900mg of oxalates per 100g, making it one of the highest-oxalate foods — there is no "recommended" oxalate intake, but dogs prone to calcium oxalate stones should minimize high-oxalate foods. Low-oxalate alternatives like kale, bok choy, and broccoli provide similar nutrients without the calcium-blocking effect. Cooking and draining water reduces oxalate content somewhat.
0.03% of daily nutrient intake
Oxalate Level makes up 0.03% of your dog's total daily nutritional requirements by weight. That's a tiny amount — but it matters.
Oxalates are not a nutrient, so there is no deficiency state. They are something to be aware of rather than something to supplement.
Chronic high oxalate intake can reduce calcium absorption, contribute to calcium oxalate bladder or kidney stones (especially in predisposed breeds like Miniature Schnauzers, Bichon Frises, and Lhasa Apsos), and in extreme cases irritate the urinary tract.
| Life Stage | Size | Min | Max | Unit | Notes |
|---|---|---|---|---|---|
| Adult | medium 10-25kg | 0 | 100 | mg | Not a nutrient but an anti-nutrient to limit. Dogs prone to calcium oxalate stones should minimize high-oxalate foods. |
Source: general veterinary consensus
Oxalates bind to calcium in the digestive tract, forming insoluble calcium oxalate crystals that cannot be absorbed. This reduces the bioavailability of dietary calcium and, in susceptible dogs, contributes to calcium oxalate bladder stone formation.
What this means: If your dog is prone to calcium oxalate stones, choose low-oxalate greens (kale, bok choy, broccoli) over high-oxalate options (spinach, chard). When feeding moderate-oxalate foods, pair them with calcium-rich foods so the oxalate binds calcium in the gut rather than in the urinary tract.
