Senior dog new food intolerance advice

A senior dog developing a reaction to food they've eaten for years is more common than people realise — as dogs age, their digestive systems become less resilient and intolerances can emerge even to previously well-tolerated proteins. True food allergies are actually less common than intolerances, and the most effective fix is usually an elimination diet using a novel or hydrolysed protein source they haven't eaten before. To point you in the right direction: what symptoms are you seeing, how long has this been going on, and has your Cairn Terrier seen a vet recently?

That pattern — itchy skin, ear irritation, and soft stools together — is a classic food intolerance presentation, and the fact it's developed gradually after years on the same food fits the senior dog picture well. The vet's advice to switch protein is spot on. What I'd want to know before recommending something specific: is she on any joint supplements or other foods alongside her main meals, and is she currently at a healthy weight? At 13, Cairn Terriers can start losing condition, so the food needs to support that too.

Great — a healthy weight at 13 means you have more flexibility with food choice, and you're not dealing with a dog who needs a therapeutic diet. Since she's been on fish for four years, you want to move to a protein she genuinely hasn't had before. Turkey is a good novel protein choice for dogs with a fish-based history, and it tends to be gentle on older digestive systems. I'd recommend Forthglade Complete Grain Free Turkey with Potato — it's a wet food, which also helps with hydration in senior dogs, uses a single named protein, and has no common allergens like wheat or dairy. The texture is soft, which suits older dogs well. Switch over 10 days, replacing about 25% of the old food with the new each few days. Keep the glucosamine chew going — there's nothing in Forthglade Turkey that will clash with it.

Skin symptoms are the slowest to resolve — typically four to eight weeks before you see meaningful improvement, even if the food is the right call. The digestive symptoms like loose stools often settle faster, sometimes within two to three weeks of a clean switch. The key is keeping everything else constant during that period — no treats with fish or mixed proteins, no table scraps. If symptoms haven't improved at all after six weeks on the new food, it's worth going back to the vet to discuss a hydrolysed protein diet, which breaks proteins down small enough that the immune system usually won't react. But try the novel protein route first — it works well in the majority of cases.

Good plan. Keep a simple log of her symptoms — even just a quick note every few days — so you can see whether things are genuinely improving. At 13 she deserves a bit of detective work to get her comfortable again, and the signs are good that this is straightforward to fix.