How do I change my dog’s food?

ByDerek

Changing your dog’s food sounds simple.

Finish one bag and open another.

For some dogs, that causes no obvious problem. For others, a sudden change can lead to loose stools, diarrhoea, wind, vomiting or simply refusing the unfamiliar food.

Unless your vet has advised you to change immediately, I would normally introduce a new diet gradually.

That gives your dog’s digestive system time to adjust and gives you a much better chance of noticing whether the new food actually agrees with them.

For wider feeding advice, start with my Dog Food & Nutrition Guide.

Summary

  • Change your dog’s food gradually unless your vet advises otherwise.
  • No single transition timetable suits every dog.
  • For many dogs, around 7 to 14 days is a sensible transition period.
  • Start with mostly the familiar food and a small amount of the new food.
  • Gradually increase the new food while reducing the old food.
  • Dogs with sensitive stomachs may need a slower transition.
  • Puppies should normally stay on their familiar food while settling into a new home before unnecessary dietary changes.
  • Do not repeatedly switch foods to treat persistent diarrhoea, itching, or other symptoms without veterinary advice.
  • Prescription and therapeutic diets may need a transition plan from your vet.
  • Contact your vet if your dog develops repeated vomiting, significant diarrhoea, blood in their stool, lethargy, pain, food refusal or another worrying change.

Table of contents

Why should I change my dog’s food gradually?

Your dog’s digestive system becomes accustomed to their usual diet.

Changing the ingredients, protein sources, fat levels, fibre, calorie density and other parts of that diet suddenly can sometimes upset digestion.

The PDSA advises introducing a new dog food gradually, rather than switching overnight, and currently suggests allowing roughly two weeks for the process.

The British Veterinary Association also recommends making significant changes to a dog’s diet gradually to reduce the risk of digestive problems.

[EXTERNAL LINK: BVA – What Should I Feed My Dog?]

That does not mean every healthy dog needs exactly 14 days.

Some dogs tolerate changes easily.

Others need considerably longer.

The dog in front of you matters more than reaching a particular percentage on a particular date.

How long should it take to change dog food?

For many healthy adult dogs, I would allow approximately 7 to 14 days.

PDSA currently uses a transition lasting roughly two weeks.

WSAVA advises a slow transition over at least several days for healthy pets and notes that animals with medical conditions may require longer.

[EXTERNAL LINK: WSAVA – Feeding Method Questions]

I prefer not to turn this into a rigid rule.

If your dog has eaten the same food for years and has a sensitive stomach, I would be more cautious than I might be with a healthy adult dog who has previously changed foods without difficulty.

A simple dog-food transition schedule

This is an example rather than a prescription.

Days 1 to 3

Keep feeding mostly the familiar food.

Introduce only a small amount of the new food.

PDSA currently suggests initially offering a small amount separately so you can see whether your dog is willing to eat it.

Days 4 to 6

If everything appears normal, begin increasing the new food while reducing the old food.

You might now be feeding roughly:

75% old food

25% new food

The percentages do not have to be mathematically perfect.

The important point is that most of the diet is still familiar.

Days 7 to 9

If stools, appetite and general behaviour remain normal, you can move towards approximately:

50% old food

50% new food

Days 10 to 12

Continue towards:

25% old food

75% new food

Days 13 to 14

If your dog is doing well, phase out the remaining old food.

You can then feed the new diet.

Some dogs will manage this more quickly.

Some should move more slowly.

Don’t increase the new food simply because the calendar says it is Tuesday if your dog’s digestion tells you otherwise.

Do I have to use exact percentages?

No.

You will often see transition charts using:

75/25

50/50

25/75

They are useful because they make the principle easy to understand.

They are not magic percentages.

Your dog does not know whether today’s bowl contains precisely 24% or 27% new food.

What matters is making a progressive change while watching how the dog responds.

Should I mix the old and new food together?

For most dogs, the two foods can be gradually combined.

PDSA’s current approach starts by offering a small amount of the unfamiliar food separately before beginning to mix increasing amounts into the established diet.

That can be useful if you do not yet know whether your dog likes the new food.

If your vet or the food manufacturer has given you specific transition instructions, follow those instead.

What should I watch during the transition?

Do not just watch whether your dog empties the bowl.

Also notice:

  • appetite
  • stool consistency
  • number of bowel movements
  • vomiting
  • excessive wind
  • abdominal discomfort
  • changes in thirst
  • energy
  • itching
  • skin or ear problems
  • weight
  • general behaviour

A small temporary stool change does not necessarily mean the new diet is unsuitable.

But persistent or worsening symptoms deserve attention.

What if my dog gets diarrhoea after changing food?

A sudden change of diet is one possible cause of diarrhoea.

PDSA notes that diarrhoea associated with a food change will often settle relatively quickly in an otherwise well animal, but persistent, worsening or concerning diarrhoea needs veterinary advice.

[EXTERNAL LINK: PDSA – Diarrhoea After a Change of Food]

If loose stools start while you are transitioning, I would not simply keep increasing the percentage of new food.

Slow down.

If appropriate, return to the previous stage of the transition that your dog was tolerating.

Contact your veterinary practice if the diarrhoea is significant, repeated, persistent or accompanied by other symptoms.

Young puppies, older dogs and dogs with medical conditions may need veterinary advice sooner.

For wider first-aid and health information, see my Dog Health & First Aid Guide.

[INTERNAL LINK: /first-aid.html]

When is diarrhoea more worrying?

Contact your veterinary practice if your dog has diarrhoea alongside:

  • repeated vomiting
  • blood in the stool
  • significant lethargy
  • weakness
  • obvious abdominal pain
  • refusing food or water
  • dehydration
  • collapse
  • another significant change in behaviour

Do not automatically assume that diarrhoea during a food transition was caused by the food.

Dogs can develop gastrointestinal illness for many reasons.

What if my dog vomits after changing food?

One isolated episode may have many possible explanations.

Repeated vomiting is different.

Stop treating the transition as a simple feeding problem and contact your veterinary practice if your dog repeatedly vomits, appears unwell, cannot keep water down, seems painful or develops other worrying symptoms.

Changing food should not be used to explain away signs of illness.

My dog refuses the new food

That does not necessarily mean anything is medically wrong.

The smell, texture or flavour may simply be unfamiliar.

Avoid immediately adding increasingly exciting extras just to persuade your dog to eat it.

Otherwise, a dog can quickly learn:

“If I leave this, something better appears.”

First ask whether your dog is still eating their familiar food normally.

If their appetite has suddenly reduced across all food, rather than just the unfamiliar product, consider whether something else may be wrong.

PDSA advises taking a significant change in appetite seriously, particularly when there are other symptoms.

[EXTERNAL LINK: PDSA – Why Is My Pet Off Their Food?]

Do I need to change my dog’s food at all?

Not necessarily.

Dogs do not have to eat a constantly changing menu simply because humans often prefer variety.

If your dog is:

  • eating a complete food appropriate for them
  • maintaining a healthy body condition
  • digesting it well
  • generally healthy
  • happy to eat it

there may be no nutritional reason to regularly switch flavours or brands.

My What Does Complete Dog Food Mean? guide explains what I mean by a complete main diet.

[INTERNAL LINK: /what-does-complete-dog-food-mean/ WHEN PUBLISHED]

Reasons you might change dog food

There are plenty of sensible reasons.

For example:

  • a puppy is approaching adulthood
  • your dog’s nutritional needs have changed
  • your vet has recommended a different diet
  • your dog needs a therapeutic food
  • the existing food is no longer available
  • the manufacturer has changed the formulation
  • your dog consistently refuses the existing product
  • the diet is impractical or unaffordable
  • your dog needs a different calorie density
  • dental problems make the existing texture difficult
  • your dog’s health circumstances have changed

The reason for changing food should influence how you make the transition.

Changing from puppy food to adult food

This should not be based simply on reaching your dog’s first birthday.

Smaller dogs generally mature sooner than large and giant breeds.

The appropriate time depends partly on expected adult size and physical development.

Once your dog is ready for adult food, introduce the new diet gradually rather than finishing the puppy food one evening and replacing it completely the next morning.

For detailed puppy advice, see my Puppy Feeding Guide.

[INTERNAL LINK: /puppy-feeding-guide/ WHEN PUBLISHED]

My Bringing a Puppy Home Guide covers the wider feeding, sleeping, toilet and settling routine during the first weeks.

[INTERNAL LINK: /bringing-a-puppy-home.html]

Changing a new puppy’s food

Bringing a puppy home is generally not the moment I would choose to make an unnecessary food change.

They are already dealing with:

  • leaving their mother and littermates
  • new people
  • a different home
  • new smells
  • a new sleeping arrangement
  • changes in daily routine
  • new experiences

PDSA recommends initially continuing with the food and routine the puppy was used to with the breeder or previous carer.

[EXTERNAL LINK: PDSA – Your Dog’s Diet]

Once the puppy has settled, you can make a gradual change if there is a genuine reason to do so.

What about rescue dogs?

The same principle applies.

A newly adopted dog may already be dealing with substantial change and uncertainty.

If their existing diet is known, suitable and available, keeping the food familiar initially can remove one unnecessary change.

There may be good reasons to alter it later.

But I would rather change things thoughtfully than decide everything in the dog’s previous life needs replacing on day one.

Changing between dry and wet food

You can change from dry food to wet food or the other way around.

The gradual transition principle still applies.

One important difference is portion size.

Wet and dry foods contain very different amounts of moisture and can have very different calorie densities.

Do not assume that:

100g dry food = 100g wet food.

Follow the feeding guidance for the new product and adjust the overall quantity accordingly.

For more detail, read my Wet, Dry, Fresh or Raw Dog Food? guide.

[INTERNAL LINK: /wet-dry-fresh-raw-dog-food/ WHEN PUBLISHED]

Can I feed wet and dry food together?

Yes, provided the foods are suitable for the dog and the total amount remains appropriate.

If both foods are complete, do not simply feed the full daily allowance of one plus the full daily allowance of the other.

That may substantially overfeed the dog.

Manufacturers may provide mixed-feeding instructions.

My How Much Should I Feed My Dog? guide covers portion sizes and total daily intake in more detail.

[INTERNAL LINK: /how-much-should-your-dog-eat.html]

Changing from kibble to fresh food

The word “fresh” does not alter the basic transition principle.

Introduce it progressively.

Check:

  • whether the new food is complete
  • whether it is appropriate for your dog’s life stage
  • how much needs to be fed
  • storage instructions
  • refrigeration requirements
  • how long an opened portion can be kept

If you are unsure how to interpret the packaging, see my How to Read a Dog Food Label in the UK guide.

[INTERNAL LINK: /how-to-read-a-dog-food-label-uk/ WHEN PUBLISHED]

Changing to raw dog food

If you are considering raw feeding, there are two separate questions.

Is the diet nutritionally appropriate?

And can it be handled safely?

A commercial raw diet can be complete, but uncooked animal ingredients introduce additional hygiene considerations.

Do not assume that a transition to raw needs to happen overnight because somebody online says different food formats cannot be mixed.

For my broader comparison, read Wet, Dry, Fresh or Raw Dog Food?

[INTERNAL LINK: /wet-dry-fresh-raw-dog-food/ WHEN PUBLISHED]

If you are considering raw feeding for a puppy, a dog with a medical condition or another dog with specific nutritional needs, discuss the change with your veterinary team.

What about homemade dog food?

Moving from a complete commercial diet to a homemade diet is a much bigger decision than changing brands.

A bowl containing meat, vegetables, rice and other apparently healthy ingredients is not automatically nutritionally complete.

If homemade food will become your dog’s main diet, use a properly formulated recipe developed for the individual dog by an appropriately qualified veterinary nutrition professional.

Do not use the transition period to gradually replace a nutritionally complete food with an unbalanced homemade mixture.

Changing food because my dog is itching

I would be careful here.

Itching, ear problems and skin irritation can have many possible causes.

Food is only one possibility.

Repeatedly changing brands and protein sources can make a proper investigation more difficult.

If your vet suspects an adverse food reaction, they may recommend a controlled elimination diet.

That needs to be followed accurately.

Treats, chews, table scraps and flavoured products can all interfere with the trial.

Do not keep randomly changing food in the hope of finding the ingredient responsible.

Changing food because my dog has a sensitive stomach

“Sensitive stomach” is a broad description rather than a diagnosis.

Some dogs genuinely tolerate certain diets better than others.

But persistent:

  • diarrhoea
  • vomiting
  • weight loss
  • abdominal discomfort
  • excessive wind
  • appetite changes

deserve veterinary investigation rather than an endless cycle of new foods.

If your dog has repeatedly reacted badly to diet changes, speak to your vet before starting another one.

Prescription and veterinary diets

If your dog has been prescribed a veterinary diet for a medical condition, follow the transition plan provided by your veterinary team.

This may apply to dogs with conditions including:

  • kidney disease
  • pancreatitis
  • diabetes
  • gastrointestinal disease
  • urinary conditions
  • confirmed adverse food reactions
  • significant obesity

Some dogs need a particularly gradual transition.

In other situations, the medical need for the new food may change the normal approach.

That decision belongs with the vet treating the individual dog.

The BVA recommends discussing dietary changes with your veterinary team when dogs have allergies or specific nutritional requirements.

[EXTERNAL LINK: BVA – What Should I Feed My Dog?]

Should I change my senior dog’s food?

Getting older does not automatically mean a dog needs to change food on a particular birthday.

Some older dogs remain healthy and maintain a good body condition on their existing diet.

Others develop changes in:

  • weight
  • muscle condition
  • mobility
  • digestion
  • teeth
  • appetite
  • health

that make another food more appropriate.

If an older dog suddenly loses weight, stops eating normally or develops digestive changes, I would not simply switch to a packet labelled “senior”.

Speak to your vet and find out whether something else is going on.

Do treats need changing gradually?

It depends on the dog and the treat.

One tiny unfamiliar training treat is very different from replacing half of the dog’s daily calories.

But introducing several new rich treats at once can still cause digestive problems.

This is especially worth remembering around:

  • Christmas
  • birthdays
  • training classes
  • holidays
  • new puppy arrivals
  • new treat deliveries

If you introduce something unfamiliar, start small.

For more on choosing treats and keeping track of the total amount, read Dog Treats: How to Choose the Right Treats for Your Dog.

[INTERNAL LINK: /treats-for-your-dog.html]

Do not forget training rewards

Food given outside the bowl still counts.

If you are changing the main diet while also introducing several new high-value training treats, it can become difficult to know what caused a digestive reaction.

Keep things relatively simple during the transition.

Part of the new complete food may eventually be useful for everyday training if your dog values it.

My Training Rewards for Dogs guide explains how I choose reward value according to the situation.

[INTERNAL LINK: /training-rewards.html]

What if I am going away?

I would avoid making a major unnecessary diet change immediately before leaving your dog with somebody else.

If your dog develops diarrhoea, vomiting or food refusal after you leave, it becomes harder to know whether the problem is:

  • the new food
  • stress
  • illness
  • treats
  • scavenging
  • something else entirely

My own pet-care approach is to maintain familiar routines.

The Finchley Dog Walker Welcome Pack asks owners to tell me about recent dietary changes, new treats, supplements and foods their pet must avoid.

[INTERNAL LINK: /welcome-pack/]

If a food change is genuinely necessary before a house sit, make it early enough that you know the dog is tolerating the new diet before you go away.

How I handle food changes when caring for your dog

I do not change a client’s dog’s food without permission.

If you have recently changed the diet, I want clear instructions about:

  • which food is being replaced
  • which new food is being introduced
  • where you are in the transition
  • how much of each food to give
  • how the food should be stored
  • which treats are permitted
  • what your dog’s normal stools and appetite are like
  • what you want me to do if something changes

Consistency matters when somebody else is following the routine.

[INSERT RELEVANT HOUSE-SITTING CTA HERE]

My simple food-change checklist

Before changing your dog’s diet, ask:

Is there a good reason for the change?

Do not switch simply because somebody online says your existing format is wrong.

Is the new food complete?

If it is going to become your dog’s main diet, check its nutritional purpose.

Read What Does Complete Dog Food Mean? if you are unsure.

[INTERNAL LINK: /what-does-complete-dog-food-mean/ WHEN PUBLISHED]

Is it appropriate for my dog?

Check age, life stage and any health requirements.

How much does my dog actually need?

The new food may contain a different number of calories per gram.

Check the feeding guidance.

Do I have enough old food left?

Do not wait until the old bag is empty before deciding to transition.

Keep enough to make the change gradually.

Can I keep everything else fairly consistent?

Avoid introducing five new treats and a new main diet at the same time.

Am I watching the dog rather than just the timetable?

Appetite, stools and wellbeing matter more than reaching the next percentage on a particular date.

Frequently asked questions

How many days should I take to change my dog’s food?

For many healthy dogs, around 7 to 14 days is a sensible guide.

PDSA currently recommends a slow change over approximately two weeks.

Some dogs tolerate a faster transition while sensitive dogs may need longer.

Can I change my dog’s food immediately?

Sometimes there may be a veterinary reason to do so.

For an ordinary planned diet change, gradual introduction is generally preferable.

What happens if I change dog food too quickly?

Some dogs may develop loose stools, diarrhoea, vomiting, wind, digestive discomfort or food refusal.

Others may appear unaffected.

Should I stop the new food if my dog has diarrhoea?

Do not continue increasing it automatically.

Slow the transition and contact your vet if diarrhoea is persistent, significant or associated with other symptoms.

Can I mix two dog foods together?

Yes, in many situations.

During a transition, gradually mixing increasing amounts of the new food with decreasing amounts of the old food is a common approach.

Can I mix two different brands of dog food?

Yes, provided they are appropriate for your dog and the total amount remains suitable.

The important issue is the complete diet and total calorie intake rather than whether both foods display the same logo.

Can I change from wet food to dry food?

Yes.

Make the change gradually and remember that wet and dry foods have different moisture and calorie densities.

Follow the feeding guidance for the new diet rather than replacing one gram with one gram.

Can I change from kibble to raw food?

A gradual transition can still be used.

Raw feeding also involves separate nutritional and hygiene considerations that need to be considered before making the change.

My dog will not eat the new food. Should I leave it down until they do?

I would not turn feeding into a battle.

Check whether your dog is otherwise eating normally and whether there are any signs of illness.

If appetite has significantly changed rather than your dog simply disliking one unfamiliar product, contact your veterinary practice.

Should I change my dog’s food if they are itchy?

Not without considering other possible causes.

Speak to your vet if itching is persistent, particularly before starting an elimination diet or repeatedly removing ingredients.

Should I change food before my dog goes to a sitter?

Avoid an unnecessary major change immediately beforehand.

Keeping the normal food and routine makes it easier for the sitter and easier to identify any unexpected health changes.

Dog Food & Nutrition Guide

[INTERNAL LINK: /dog-food-nutrition.html]

How Much Should I Feed My Dog?

[INTERNAL LINK: /how-much-should-your-dog-eat.html]

What Does Complete Dog Food Mean?

[INTERNAL LINK: /what-does-complete-dog-food-mean/ WHEN PUBLISHED]

How to Read a Dog Food Label in the UK

[INTERNAL LINK: /how-to-read-a-dog-food-label-uk/ WHEN PUBLISHED]

Puppy Feeding Guide

[INTERNAL LINK: /puppy-feeding-guide/ WHEN PUBLISHED]

Wet, Dry, Fresh or Raw Dog Food?

[INTERNAL LINK: /wet-dry-fresh-raw-dog-food/ WHEN PUBLISHED]

Dog Treats: How to Choose the Right Treats for Your Dog

[INTERNAL LINK: /treats-for-your-dog.html]

Training Rewards for Dogs

[INTERNAL LINK: /training-rewards.html]

Dog Health & First Aid Guide

[INTERNAL LINK: /first-aid.html]

Trusted external information

PDSA: Your Dog’s Diet

[EXTERNAL LINK: PDSA]

PDSA: Diarrhoea After a Change of Food

[EXTERNAL LINK: PDSA]

British Veterinary Association: What Should I Feed My Dog?

[EXTERNAL LINK: BVA]

WSAVA: Global Nutrition Guidance

[EXTERNAL LINK: WSAVA]

Final thoughts

Changing dog food does not need to be complicated.

For most healthy dogs, make the change gradually.

Start with mostly the familiar diet.

Introduce a small amount of the new food.

Increase it progressively while reducing the old food.

Then watch your dog.

Their appetite, stools, comfort and general wellbeing tell you more than whether you have reached day seven on a feeding chart.

Some dogs can change relatively quickly.

Others need much longer.

And if your dog has persistent digestive problems, a diagnosed medical condition, significant food refusal or another worrying symptom, stop treating it simply as a question of changing brands and speak to your veterinary team.

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[INSERT VETERINARY DISCLAIMER]

This guide provides general information about changing food for healthy dogs. It does not replace individual veterinary advice. Speak to your veterinary practice before making significant dietary changes if your dog is growing, pregnant, has a diagnosed medical condition, receives a prescription diet, has persistent digestive problems or has previously reacted badly to dietary changes. Contact your veterinary practice promptly if your dog develops repeated vomiting, significant or bloody diarrhoea, lethargy, pain, weakness, persistent food refusal or another worrying change.

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