How to Switch Dog Food: A 7–10 Day Plan
Switch your dog's food gradually over 7–10 days by mixing more new food into the old each day. Here's the schedule, signs of upset and when to call a vet.
Sunny · · 4 min read
The safest way to switch dog food is gradually, over about 7–10 days. Each day you mix a little more of the new food into the old, so your dog's gut has time to adjust. A sudden change is one of the most common causes of tummy upsets in dogs.
Whether you're moving from puppy to adult food, changing brands, or following your vet's advice, the method is the same.
Why go slowly?
Your dog's digestive system, including the bacteria in their gut, gets used to a particular diet. Different foods vary in protein, fat, fibre and ingredients. Swapping overnight can lead to diarrhoea, vomiting, wind or a dog who won't eat. Going gradually gives the gut time to adapt and helps fussy dogs accept the new taste.
The 7–10 day transition plan
Use the feeding guide on the new food's packaging to work out the total daily amount for your dog's weight, then split it between old and new food like this:
| Days | Old food | New food |
|---|---|---|
| 1–2 | 75% | 25% |
| 3–4 | 50% | 50% |
| 5–6 | 25% | 75% |
| 7 | 10% | 90% |
| 8 onwards | — | 100% |
For a slower 10-day switch — a good idea for puppies, older dogs and dogs with sensitive stomachs — spend three days at each stage instead of two. Some dogs need two weeks or more, and that's fine.
Signs the switch isn't going well
Mild changes in stool, such as slightly softer poos for a day, are common. Slow down if you notice:
- loose stools or diarrhoea
- vomiting
- lots of wind or a gurgling tummy
- your dog leaving food or picking out the old kibble
If this happens, go back to the last mix your dog was comfortable on and stay there for a few extra days before moving on. Keep treats and table scraps to a minimum during the change so you can tell what's causing any upset.
Switching from puppy food to adult food
Puppy food has extra calories, protein and carefully balanced minerals to support growth. When to switch depends mainly on your dog's expected adult size:
| Adult size | Typical switch age |
|---|---|
| Small breeds | Around 10–12 months |
| Medium breeds | Around 12 months |
| Large breeds | Around 12–18 months |
| Giant breeds | Up to 18–24 months |
These are rough ranges. Large and giant breeds need food designed for large-breed puppies, with controlled calcium and energy to support healthy bone growth, so don't switch them too early. Your vet can check your puppy's growth and tell you when they're ready — a good time to ask is at a routine visit, such as their vaccination appointments.
When a quick switch is necessary
Sometimes you can't go slowly — your dog's food has been recalled, it's unavailable, or your vet has prescribed a special diet. In that case:
- Ask your vet whether the new food can be started straight away (many prescription diets can).
- Feed smaller meals more often for the first few days.
- Watch closely for vomiting or diarrhoea.
Avoid sudden switches for puppies and dogs with health conditions unless your vet advises it.
Tips for fussy eaters
- Stick to set mealtimes and pick up uneaten food after 15–20 minutes.
- Warm wet food slightly to bring out the smell.
- Avoid adding lots of human food to tempt them — it can create a fussier dog. Some foods, like onion and garlic, are dangerous; see our list of foods that are toxic to dogs.
- If your vet recommends a temporary bland diet for an upset stomach, our guide to feeding rice to dogs explains how it's usually done.
Frequently asked questions
What happens if I switch dog food too quickly?
A sudden change can cause vomiting, diarrhoea, wind or a dog refusing to eat. Most dogs recover once they go back to the old food and switch more slowly.
When should a puppy switch to adult food?
It depends on size. Small and medium breeds are usually ready at around 10–12 months, while large and giant breeds may need puppy food until 12–24 months. Ask your vet for your puppy's breed and growth.
Can I mix wet and dry dog food?
Yes, as long as both are complete foods and you reduce the amount of each so the total calories stay the same. Introduce any new food gradually.