A diet trial only works if the record is exact
When a dog has recurring stomach trouble, a diet trial is an experiment, and an experiment is only as good as its notes. Memory is not good enough here. After two weeks, no owner can honestly recall whether the loose stool came before or after the portion increased, or whether the good days coincided with the new food alone or with a quiet weekend and no treats. A daily log written at the time turns a frustrating blur into evidence your vet can use to decide whether this food helps your dog.
Set up the log before the first trial meal, with the same columns every day. You need the food exactly as fed, the amount served, the amount actually eaten, and the output side of the story: stool consistency and frequency, any vomiting, gurgling, grass eating, flatulence that is unusual for him, and his appetite and energy. Fixed columns matter because the days you most want to skip recording are usually the messy days that carry the most information.
Record food the way a stranger could repeat it
Write the food in full detail on the first day and whenever anything changes: the exact product or home-cooked ingredients, the form it was served in, and how it was prepared. Then record amounts with the same measure every time. Weighing portions on a kitchen scale is the most reliable method during a trial, because scoops vary between people and between days, but if you use a cup or scoop, use the identical one and note the level honestly rather than rounding to what the plan says.
Log everything else that passes his lips, without exception. During a stomach trial, treats, chews, training rewards, table scraps, scavenged items on walks, and food stolen from another pet can all invalidate a week of careful feeding. The cleanest approach is to pause treats entirely or use a tiny amount of the trial food itself as the reward, as your vet advises, and to write down lapses when they happen rather than quietly restarting the count. One honest note about a stolen sandwich explains a bad day better than a mysterious setback in an otherwise perfect log.
Score the output side consistently
Describe stool the same way each day so changes are visible. A simple scale you define at the top of the log works: firm and formed, soft but holding shape, loose, or watery, plus how many times that day and whether there was urgency, straining, mucus, or blood. Note timing in relation to meals in rough terms, such as overnight or shortly after eating, because patterns linking a meal to a reaction are exactly what your vet will look for.
Protect the trial from everyday drift
Do not change two things at once. If you switch food and also change feeding times, portion size, and treats in the same week, the log cannot tell you which change helped. If your vet has advised a gradual transition onto the new food, record the mixture proportions each day during that transition, because symptoms during a changeover mean something different from symptoms on the full new diet.
Contact your vet promptly during a trial if your dog vomits repeatedly, passes blood, refuses food for a full day, seems in pain, becomes lethargic, or loses weight noticeably. A trial is a planned observation, not a reason to push through signs that need care, and your log will help the vet judge what is happening.
At the review, hand over the whole log rather than summarizing it. The pattern across days, including the lapses and bad days, is what makes the record trustworthy and the next decision sound. Storing that day-by-day log alongside his other health records in KinsLe Pet Passport means the full trial, not just its conclusion, is there for any vet who treats him next.