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from the dog health hub

Why tummies improve before skin

by Ben, co-founder · updated July 2026 · 1 min read

Two dogs switch to the same food on the same day. Two weeks later, one family is celebrating the best poos in months while the other stares at the same scratching and wonders if anything's happening. Both dogs can be right on track.

The gut is quick

When tummy trouble is food-related, it tends to respond fast - often within about two weeks of a full switch. The early wins to look for: firmer poos, smaller poos, fewer of them, less gurgling, less of the 3am grass-eating urgency.

Skin is slow

Skin runs on a much longer clock. Skin cells take weeks to turn over, and the immune reaction behind food-allergic itching winds down gradually rather than switching off. The biggest review of food-allergy studies found about half of food-allergic dogs show a marked drop in itching by week three, more than 8 in 10 by week five, and over 95% by week eight.

That's the whole reason a proper food trial runs eight weeks. A fortnight tells you almost nothing about skin.

What to do with this

  • Weeks one and two: judge the tummy only. Poo quality is your early signal.
  • Don't read anything into the skin before week three. No change yet means nothing.
  • From week four, compare against your day-one video, never against yesterday.

the evidence

Skin timeline: Olivry, Mueller & Prélaud 2015, BMC Veterinary Research. Gut response: Allenspach 2016, via Today's Veterinary Practice.

So if the poos have improved but the scratching hasn't budged, the food is agreeing with them and the skin simply hasn't had time yet. Keep going.

the food behind the guide

One novel protein.
None of the usual suspects.

Some Grub is a cold-pressed, hypoallergenic dog food built around insect protein — a protein most dogs have never met, which is the whole point of a food trial.

See the food →

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