Once you’ve chosen an ingredient direction, quality controls determine whether the product is likely to be effective—and safe.
1) **Testing proof:** Look for a published **certificate of analysis** (COA) or batch testing that includes contaminants. For fish oil, confirm screening for **heavy metals** (and ideally PCBs/dioxins).
2) **Freshness metrics:** Oxidized oils can be less useful and more irritating. Brands that disclose oxidation testing (e.g., **peroxide value** and anisidine value, or a combined TOTOX) give you a clearer read on freshness.
3) **Packaging and storage:** Prefer light- and oxygen-protective packaging (dark bottles, blister packs, nitrogen-flushed softgels). Follow **storage** directions—some oils need refrigeration after opening, and heat exposure during shipping can matter.
4) **Dosing transparency:** The label should state EPA/DHA (or other actives) and provide dosing guidance **per kg** (or per lb) so you can match your dog’s size and goal. If dosing is only “one chew for all dogs,” it’s often underpowered for large breeds.
5) **Calorie impact:** Oils and chews add calories; account for this if weight management is a concern.
If a product can’t show testing, freshness standards, and clear per-kg dosing, it’s hard to call it “best.” (Author, Year)
