Why position on the ingredient list matters
Third ingredient means trout comprises likely less than 5% of that chew's total content — a negligible amount for your 35 kg Lab. Manufacturers use small quantities of fish proteins like trout for palatability rather than nutritional impact. At his size, even if the chew was 10% trout (unlikely), it wouldn't approach levels that affect his system.
Compare this to eating a single bite of actual trout fillet — the chew contains perhaps 1/50th of that amount. The fish undergoes extensive processing when made into supplements, breaking down proteins and fats into highly digestible forms unlikely to trigger sensitivities.
How big dogs handle trace fish proteins
A Labrador's digestive system manages novel proteins more easily than smaller breeds, with greater enzyme production and intestinal capacity. What might give a 5 kg dog loose stool often passes unnoticed in a dog his size. The trout in supplements is also typically hydrolyzed — pre-digested during manufacturing to prevent reactions.
His weight provides another buffer: the same chew given to a 5 kg dog delivers seven times more fish protein per pound of body weight. For your Lab, it's metabolically insignificant unless he has known fish allergies, which you'd have noticed from regular food before now.
When supplements cause more concern than ingredients
The glucosamine itself is more likely to cause soft stools than the trout content, especially if this is his first time with the supplement. Some dogs experience mild digestive upset when starting joint supports, unrelated to the protein sources. This usually resolves within three doses as their system adjusts.
Watch his next bowel movement for texture changes — slightly looser stool is common but shouldn't progress to diarrhea. If it does, the culprit is probably the supplement base (often including sweeteners or binders) rather than the minute fish component. Always introduce new chews with a meal to slow absorption.
Why water matters after any supplement
Glucosamine supplements tend to pull water into the digestive tract, which can cause mild dehydration if your dog doesn't drink adequately. The tiny amount of trout protein increases this need slightly due to its high digestibility rate. Offer fresh water immediately after he takes any chew, especially if he's prone to gulping treats without chewing thoroughly.
For a 35 kg dog, aim for at least two cups of water within the hour after the supplement. This helps prevent any constipation from the binding agents while ensuring proper nutrient absorption. The trout content is so minimal it doesn't require special hydration beyond normal good practice with supplements.
The full verdict, portion guidance and serving notes are collected on the Trout food facts page.