How to Introduce New Foods Without Upsetting Your Dog’s Stomach
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Switching your dog’s food can be stressful for both pet and owner-even a tasty upgrade can cause digestive upset if done too quickly.
A gradual diet transition is key to preventing vomiting, diarrhoea, or decreased appetite.
Table of contents
Why Do You Need To Transition Slowly? Why Some Foods Upset Dogs’ Stomachs More Than Others Signs Your Dog Has an Upset Stomach What to Do if a New Food Upsets Their Stomach Supporting Digestion During Transition Introducing Years – Smart, Fresh Dog Food The 7 Day Transition Plan for Years Conclusion
Why Do You Need To Transition Slowly?
A dog’s digestive system needs time to adjust to new amounts and sources of proteins, fats and fibre. Research shows that gradual diet changes significantly reduce rates of diarrhoea in pets.
Veterinary associations recommend transitions over five to seven days as standard practice. And pet owners regularly report that sensitive dogs fare better when changes are made slowly.
Why Some Foods Upset Dogs’ Stomachs More Than Others
Many commercial dog foods are made with ultra-processed ingredients, artificial additives, and low-moisture content-all of which can irritate your dog’s digestive system.
Kibble and canned foods tend to be cooked at high temperatures, which denatures proteins and reduces nutrient availability. They also often have high amounts of simple carbohydrates, such as wheat, white potato and white rice, which can negatively impact the blood glucose of your dog. This is often associated with behaviours like becoming frantic after a meal, or crashing and becoming grumpy an hour or two after eating. It's also common for these types of foods to list "meat by-products" as an ingredient, which can lead to unknown food intolerances, and has unknown nutrient composition and availability.
Fresh food, like Years, is different. It’s gently cooked to retain nutrients and made from real, whole ingredients - lean meats, vegetables, seeds, and herbs - with no artificial preservatives. Plus, its high moisture content supports hydration and helps keep digestion regular.
This is why dogs often adjust better and feel healthier on a fresh food diet. It’s closer to what their bodies naturally expect.
Common Ingredients That Upset Dogs’ Stomachs
Many commercially available dog foods contain ingredients that are harsh on your dog’s digestive system - especially when fed long-term or introduced without care. While some dogs tolerate these ingredients, others may develop chronic digestive issues as a result.
- High cereal content – Ingredients like corn, wheat, soy, and rice bran are often used to add calories to the food. These ingredients have a higher glycaemic index which can quickly raise blood glucose in an unsustainable way, leading to large fluctuations.
- Meat meals and by-products – These are rendered from various animal parts and can vary widely in quality. They're often harder to digest than fresh meat and are often heavily processed.
- Artificial preservatives and flavours – Chemicals like BHA, BHT, and artificial dyes are still used in some dry foods, and have been linked to gut irritation and food sensitivities.
- Excess fats – Many mass-market foods include added animal fats or greasy trimmings to improve palatability, which can overwhelm your dog’s digestive system and increase the risk of pancreatitis.
Switching to a high-quality fresh food like Years avoids these common irritants. Years is made from real, recognisable ingredients - whole cuts of meat, fresh vegetables, fruits and seeds - with no artificial additives or poor quality ingredients. For many dogs, this leads to noticeably better digestion and fewer stomach issues, especially when the transition is done gradually.
Better digestive health can have wide-reaching benefits for dogs, including improved longevity by supporting nutrient absorption and overall organ function, a reduced incidence of disease through a stronger immune system, enhanced emotional regulation by maintaining a healthy gut-brain connection, and better behaviour as a result of improved comfort, reduced stress and balanced energy levels throughout the day.
Signs Your Dog Has an Upset Stomach
Here are some signs your dog might not be adjusting well to a new food:
- Soft or runny stools
- Increased flatulence
- Vomiting
- Loss of appetite
- Lethargy or low energy
- Whining or restlessness after meals
- Abdominal bloating or discomfort
If any of these occur during a transition, pause and evaluate. Minor loose stools in the first few days are common and often resolve without issue. But persistent symptoms should not be ignored.
Years subscribers can access a free 15 minute call with our canine nutritionist to talk through any transition problems they may be having.
Click here to email the customer service team to book a call.
What to Do if a New Food Upsets Their Stomach
- Slow the transition. Go back to the previous successful ratio, where your dog was symptom-free, and stretch the process over more days.
- Temporarily revert to their old food if symptoms worsen or they stop eating entirely.
- Avoid treats or other dietary variables during transition periods.
- Hydrate. Ensure your dog drinks enough water, especially if experiencing diarrhoea. Try adding Years bone broth to their water to encourage them to drink.
- Contact your vet if symptoms persist longer than 48 hours, or if you notice blood in the stool, repeated vomiting, or signs of dehydration.
In many cases, a slower pace and added probiotic support can make all the difference.
Supporting Digestion During Transition
- Monitor stool quality daily. Aim for a log-shaped, firm consistency.
- Stick to consistent feeding times.
- Avoid feeding high-fat or unfamiliar treats during the transition.
- Consider digestive supplements or prebiotics (some are built into Years' Breed Health+ blend).
- Stay observant. Trust your instincts-if your dog seems off, adjust the plan or consult a professional.
Introducing Years – Smart, Fresh Dog Food
Years is a fresh, wholefood dog nutrition system developed by chefs and veterinary nutritionists at Years.com in Nottinghamshire. It uses prime cuts of unprocessed meat, fruits, vegetables, seeds, and tailored Breed Health+ supplements with probiotics to support gut health and digestion. It currently holds the highest rating (96%) of all UK fresh dog foods on All About Dog Food.
Because Years meals are nutrient-dense and compositionally different from kibble or generic wet food, a careful transition is recommended.
The 7 Day Transition Plan for Years
Follow this plan to help your dog adjust gently:
|
Day(s) |
% of Years food |
% of Current food |
| Days 1–3 |
25% |
75% |
| Days 4–5 |
50% |
50% |
| Day 6 |
75% |
25% |
| Day 7 |
100% Years |
0% |
We’ve found this works well for most dogs. But for sensitive tummies, you might stretch this over 10 days or even longer. You know your dog best-go at the pace they need.
Conclusion
- Always transition to a new food slowly, ideally over 7–10 days.
- Watch for signs of stomach upset and adjust the pace if needed.
- Avoid high-fat, spicy, or inconsistent foods during transitions.
- Hydrate, monitor closely, and contact a vet if symptoms worsen.
- Years food is designed to be gentle and nutritious-but every dog is different. Go at their pace.
What should I do if my dog won’t eat their new food?
If your dog refuses new food, try mixing in small amounts with their current meals and increase gradually. Warming the food slightly or adding warm water can enhance the smell and encourage fussy eaters. Most picky dogs adjust with time and consistency.
Can I switch my dog’s food faster than 7 days?
Speeding up a dog food transition isn’t recommended. Switching too quickly can cause diarrhoea, vomiting, or loss of appetite. Stick to a gradual 7–10 day plan to protect your dog’s digestion - especially if they have a sensitive stomach..
What if my dog vomits after eating new food?
If your dog throws up after eating new food once, it may just be part of adjusting. But repeated vomiting, lethargy, or signs of discomfort should not be ignored. Pause the new diet, revert to their previous food and speak to your vet before continuing the transition..
Is Years dog food good for sensitive stomachs?
Yes. Years is formulated for easy digestion using fresh and whole ingredients while the Years Complete Nutrition System contains an added probiotic. It’s free from common irritants like cereals, artificial preservatives, and meat meals-making it an excellent option for dogs with sensitive stomachs or food intolerances.
About the author
Alyssa
Alyssa Ralph – MSc PGDip BSc(Hons)
Alyssa is a dual-qualified Clinical Animal Behaviourist and Canine Nutritionist with three degrees in behaviour, welfare and nutrition. She specialises in the link between emotional wellbeing and diet, helping dogs and their caregivers lead healthier lives. Having supported hundreds of dogs with issues like reactivity, anxiety and fussy eating, her work often transforms both health and behaviour.
