Fuel the work, not just the dog
A dog running in harness several times a week is an athlete with a training load, and his food should match the week's work rather than an average pet day. The generic guide printed for an average pet dog undershoots a dog in harness work, while simply doubling dinner overshoots him in a single gut-straining meal. The sensible middle is a structured rise, spread across the day and adjusted by what his body tells you.
Start from his current food and weight. A complete food that already suits his stomach is the base to build on; endurance training is the wrong moment to gamble on novelty, because you need to know that loose stools mean workload or timing, not an untested recipe.
Timing meals around the harness
The firmest rule is separation: no substantial meal in the couple of hours before a run, and no run straight after a full bowl. A stomach working hard on food while the body works hard in harness invites vomiting, discomfort and, in deep-chested breeds, raises a risk vets take very seriously. Give a small, early light meal if a morning run follows a long overnight fast, then save the main feeding for afterwards.
After the run, let him cool, settle and drink in small amounts first. Once breathing is normal and he is relaxed, usually after a comfortable pause rather than the moment you unclip the line, feed the day's larger meal. That post-run meal is where recovery happens, supplying the energy the run spent and the protein ongoing training demands. Evening runs simply reverse the pattern: main meal afterwards, with a modest earlier feed keeping him comfortable through the day.
Portions across a training week
Raise the overall ration gradually as training builds, adding a little to the post-run meal first, and judge the result weekly by condition. You should feel his ribs easily beneath a thin layer, see a waist from above and the side, and watch muscle develop over shoulders and thighs. Losing condition on a rising workload means the ration still lags the work; softening over the ribs during a lighter week means rest days are being fed like run days.
That is the other half of the plan: rest days are not run days. Trim portions slightly when no session is scheduled, keeping meal times and the food itself identical so his gut sees rhythm rather than randomness. Weigh him regularly during a training block, because the scales catch drift weeks before the eye admits it, and discuss sustained heavy training, rapid weight change or a dog who fades late in runs with your vet, who may advise a food built for working dogs.
Water, extras and the small print
Hydration is feeding's partner. Offer water before leaving, in small stops on long sessions where practical, and freely in modest amounts afterwards rather than allowing one frantic, enormous drink. Training treats should be tiny and counted, because a pocketful of rewards across several sessions quietly becomes another meal. Avoid experimenting with rich fatty extras the night before a hard run in the hope of loading him like a human marathoner; dogs use fuel differently, and a greasy experiment most reliably produces a messy run.
Warm-up, cool-down and rest days between hard efforts protect the body the food is fuelling, and appetite is itself a training signal: a dog who suddenly leaves meals during a block may be overreached, sore or unwell, not stubborn.
Running the plan as a household
Canicross weeks involve early starts, muddy returns and more than one person often feeding the athlete. A written rhythm, run days marked, meal times and amounts set against them, rest-day portions noted, stops the post-run feast being served twice by two kind people. Keeping that training-and-feeding week visible in KinsLe Care Teams means whoever is home feeds the running dog for the work he actually did that day.