Senior Food Made My Dog Sick — How to Switch Safely

Vomiting after three days on a new food is a really common sign that the switch happened too fast — the gut simply hasn't had time to adjust, and sensitive dogs like Dalmatian mixes can be especially reactive. Senior dogs genuinely do need different nutrition: lower calories, easier-to-digest protein, and joint support tend to make a real difference at this stage. But the right food only works if the transition is slow enough for the stomach to accept it. To help you find something that'll stick, can you tell me a bit more — what exactly were you feeding before you made the switch, and what senior food caused the vomiting? Also, does your dog have any known sensitivities or health conditions beyond her age?

That makes a lot of sense. Four days is too fast for most dogs, and going from a well-established premium food like Eukanuba straight to a supermarket own-brand is a fairly significant ingredient and quality shift — not just a flavour change. The vomiting is almost certainly a transition reaction rather than a sign the senior formula itself is wrong for her. The good news is she has a solid baseline on Eukanuba, which gives us something to work back from. One question before I suggest something: is she currently back on the Eukanuba Adult, or has she been off food since the vomiting started?

Perfect — being back on the Eukanuba means you have a clean starting point, which is exactly what you need. For a 10-year-old Dalmatian mix with a sensitive stomach and no specific health conditions, I'd go with Hill's Science Plan Adult 7+ Active Longevity with Chicken. It's a well-formulated senior kibble with highly digestible protein, reduced phosphorus to support kidney health as they age, and added glucosamine and chondroitin for joints. Crucially, its ingredient profile is close enough to premium adult foods like Eukanuba that the transition is much smoother than jumping to a budget brand. Hill's is also widely trusted by vets and is available in various bag sizes on Amazon UK. For the transition itself: go over 10 days minimum — 75% old, 25% new for the first three or four days, then 50/50 for another three, then 75% new for two days, then full switch. If you see any loose stools, just pause at that ratio for an extra two days before moving on. Don't rush it.

You're right to flag that — Dalmatians have a well-documented quirk where they process purines differently from other breeds, which can lead to urate crystals in the urine. The practical implication is that you want to avoid very high-purine proteins like organ meat or game-heavy formulas, and keep her well hydrated. Hill's Science Plan 7+ actually works reasonably well here because it uses moderate chicken-based protein rather than organ-heavy or red-meat-heavy ingredients, and the reduced phosphorus supports urinary tract health more broadly. If she ever shows signs of straining to urinate or blood in urine, that's a vet conversation rather than a food swap — but for a healthy dog managed on a sensible senior diet, you're in good shape. Just make sure she always has fresh water available, especially during the transition.

That's exactly the right approach. Give it the full 10 days and don't be tempted to speed up even if she seems fine — stomachs can be deceptively tolerant for a few days and then catch up with you. If she sails through the transition, you'll have a solid senior food that should serve her well for years. Good luck with her.