Stewart is better for sensitive stomachs if the dog tolerates beef — it has one ingredient and no additives. Ziwi Peak offers more protein source variety (lamb, venison, mackerel) which matters if your dog has a known beef intolerance. Ziwi is also significantly more expensive. For dogs without protein-specific issues, Stewart is the leaner, simpler choice.
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Ingredient transparency comparison
Stewart Beef Liver: one ingredient. Beef liver. That is the complete list.
Ziwi Peak treats vary by formula, but most contain multiple ingredients including the primary protein source, organs, bone, and often New Zealand green mussel or other additions. The ingredient list is short by commercial standards but longer than a single-ingredient treat. For elimination diet purposes, this distinction matters.
If you are trying to identify a food trigger through elimination, Stewart's single-ingredient formula is cleaner. You know exactly what you are testing. Ziwi's multi-ingredient formulas, while high quality, introduce more variables to account for.
Protein source options
| Brand | Available proteins in treats | Single ingredient? |
|---|---|---|
| Stewart | Beef liver, chicken liver, chicken breast, salmon, venison liver | Yes (each flavor) |
| Ziwi Peak | Lamb, beef, venison, mackerel & lamb, chicken | No — multi-ingredient formulas |
Both offer variety, but the single-ingredient nature of Stewart's line means each option is truly isolated. A dog that reacts to chicken will not react to Stewart's salmon treats; with Ziwi's multi-ingredient formulas, cross-reactions are less predictable because the protein is combined with organs and additives from the same animal or other sources.
Price per ounce comparison
Stewart: approximately $1.96/oz for the 16oz pouch. Ziwi Peak treats typically run $3.50–5.00/oz depending on the size purchased and the retailer. The price gap is significant, and for owners using treats at daily training-session frequency, the cost difference accumulates quickly.
Ziwi's higher price reflects New Zealand sourcing (their primary selling point is 100% New Zealand-raised animals), their quality certifications, and a premium brand positioning. Whether that premium is worth it depends on your dog's specific needs and your budget.
Which is easier on a sensitive stomach
For a dog with general digestive sensitivity without known protein allergies: Stewart is the safer starting point because its ingredient simplicity makes reactions easier to attribute. If the dog reacts, you know it is beef liver. If it does not react, you have found a usable treat.
For a dog with confirmed beef intolerance: Ziwi's lamb or venison options may be appropriate, though you need to check each specific formula for any added beef-derived ingredients. Alternatively, Stewart makes a venison liver and salmon treat that are still single-ingredient but non-beef options.
Fat content matters here: Stewart beef liver is 10% minimum fat. Ziwi's formulas vary but are generally in a similar range. Neither is a low-fat treat; dogs with pancreatitis need vet guidance regardless of which brand you choose.
When to choose Ziwi Peak instead
Choose Ziwi when: your dog has a known beef intolerance and you want a premium treat from a different protein source with strong provenance claims. New Zealand-raised lamb or venison represents a genuinely different protein profile from typical North American beef, which can matter for dogs with extensive food allergy histories who have reacted to multiple common proteins.
Choose Stewart when: your dog tolerates beef, you need training-frequency quantities (cost matters), you want the cleanest possible ingredient list for elimination diet purposes, or you are comparing price-per-training-session over a month of use.