How to help manage your pet's chronic digestive issues

LAST UPDATED 31st MARCH 2025

This article is written by Pet Circle veterinarian, Dr Belinda Stancombe in partnership with Hill's Pet Nutrition.

Do you have a pet who has ongoing digestive issues? Have you already tried multiple different treatments and feel like nothing is working? Don't worry, you're not alone!

Managing a pet with long-term digestive issues can be frustrating and costly (as well as messy!). Multiple trips to the vet can be stressful for both our pets and ourselves, and it is easy to become disheartened along the way.

Unfortunately, the reality is that diagnosing and treating chronic gastrointestinal issues can be a long and winding journey, as often multiple diagnostic tests and treatment trials are involved. However, it is important to keep your mind on the end goal, and work closely with your vet to find the most appropriate plan for your pet so they can live a happy and healthy life.

If your pet is suffering from digestive upsets and requires some extra support, schedule an appointment with your vet to enquire about how a therapeutic diet, like Hill's Prescription Diet, may help.

Gastroenteritis Explained

Gastroenteritis is inflammation of the gastrointestinal tract (the stomach and intestines), and in simple terms refers to an upset stomach. Gastroenteritis is quite a common condition in our pets and can be due to many different causes with a wide range of symptoms.

    Common causes of gastroenteritis include:

  • Dietary indiscretion: eating spoiled foods or non-food items
  • Infectious causes: bacteria (eg Salmonella), viruses (eg parvovirus) or parasites (eg Giardia)
  • Changes in intestinal flora
  • A food allergy or sensitivity
  • Gastrointestinal ulcers
  • Gastrointestinal cancers
  • Foreign bodies
  • Intestinal obstruction
  • Medications
  • Toxins
  • Other diseases (eg kidney and liver disease)

    Common signs of gastroenteritis include:

  • Diarrhoea, commonly large volumes of watery stools with increased frequency
  • Vomiting
  • Blood in the stool, or black tarry faeces
  • Lethargy
  • Abdominal pain
  • Nausea, drooling, swallowing frequently
  • Decreased appetite
  • Dehydration

The Role of Therapeutic Veterinary Diets

What are therapeutic veterinary diets?

Therapeutic veterinary diets are foods which may be recommended by your pet's treating veterinarian to help manage specific health conditions.

Many retail diets can offer some extra digestive support without requiring a vet recommendation, like Hill's Science Diet Perfect Digestion, and Hill's Sensitive Stomach and Skin. They may help pets with mild stomach issues but are not specifically designed for pets with diagnosed health conditions.

That's where therapeutic veterinary diets come in. They do require a veterinary recommendation and are aimed at providing nutrition for pets with an already established health condition. Therapeutic veterinary diets, like Hill's Prescription Diet, are generally recommended by a vet for a pet suffering from an ongoing issue, and may also be used long-term to reduce the recurrence of signs of certain health conditions. Therapeutic veterinary diets are tailored to meet the key nutritional needs of pets with specific health conditions and provide benefits backed up by scientific studies.

Therapeutic veterinary diets should only be used under the recommendation and supervision of your pet's veterinarian. Pets on a therapeutic vet diet will require regular check-ups with their vet to make sure that their diet is still required, as their dietary needs may change over time.

How do therapeutic veterinary diets work?

Nutrition plays a key role in the management of chronic gastrointestinal issues, which makes sense given the job of the intestinal tract is to digest and absorb nutrients. Nutrition is so important that it is even possible to manage certain conditions with dietary therapy alone.

There are a variety of therapeutic gastrointestinal diets available from premium science backed brands, like Hill's Prescription Diet, that help the digestive tract in different ways. This includes being highly digestible (Hill's i/d Digestive Care), containing increased fibre (Hill's Gastrointestinal Biome), food and skin sensitivities (Hill's z/d) and being low in fat (Hill's i/d Low Fat Digestive Care) or food and fat sensitivities (Hill's z/d Low Fat ).

Diet Range Product Information Benefits Suitable for:
Hill's Prescription Diet Gastrointestinal Biome


•Specifically formulated to nourish the gut microbiome and promote regular healthy stools for pets prone to gastrointestinal upset •Clinically shown to help firm loose stools in 24 hours and reduce risk of recurrence
•Proprietary ActivBiome+ Digestion ingredient technology shown to rapidly activate beneficial gut bacteria and support a healthy GI microbiome balance
•Unique blend of prebiotic fibres to promote regular bowel movements and help balance digestive function
•High levels of omega-3 fatty acids (DHA & EPA)
•Adult cats and dogs
•Loose stools
•reduce stress for cats that have digestive upsets
•Complex gastrointestinal disorders
Hill's Prescription Diet i/d Digestive Care


•Clinically shown to help settle digestive upsets. •Highly digestible formula to ensure easy nutrient absorption
•High levels of electrolytes and B vitamins to replace nutrients lost from digestive upset
•Soluble and insoluble fibres (including prebiotic fibre) to promote regular bowel movements and help balance digestive function
•Complete and balanced for puppies and kittens, as well as adults
•Adult cats and dogs
•Digestive upsets
Hill's Prescription Diet i/d Low Fat Digestive Care

•Great tasting low fat nutrition clinically shown to help settle fat-responsive digestive upsets in dogs. •Low fat and highly digestible to help improve digestion, nutrient absorption & lower blood fat levels
•ActiveBiome+ Digestion ingredient technology rapidly activates the gut microbiome to support digestive health and well-being
•Unique prebiotic blend & ginger to promote beneficial gut bacteria activity & improve stool quality
•Enriched with clinically proven antioxidants & Omega-3 fatty acids
•Adult dogs
•Digestive upsets
•Dogs with fat sensitivities
Hill's Prescription Diet z/d Low Fat and Food Sensitivities

•Delicious low fat formula with highly digestible, hydrolysed soy protein for food & fat sensitivities •Low fat formula specially formulated to help manage food sensitivities in dogs
•Hydrolysed soy protein to minimise the risk of adverse reactions
•ActiveBiome+ Digestion ingredient technology rapidly activates the gut microbiome to support digestive health and well-being
•Promotes a urinary environment that reduces the risk of struvite and calcium oxalate crystals
•Adult dogs
•Dogs with fat sensitivities
•Dogs with food sensitivities
•Dogs with adverse food reactions
Hill's Prescription Diet z/d Skin and Food Sensitivities

•Delicious, highly digestible, specialised nutrition to help cats and dogs with skin and food sensitivities and digestive issues •Digestible and gentle formula with natural fiber to promote regular bowel movements
•Designed to reduce skin and gastrointestinal reactions to food
•Enhances skin and coat health with increased levels of essential fatty acids
•Enriched with essential fatty acids to nourish skin and promote a shiny coat and antioxidants such as Vitamin C and E to support a strong immune system
•Adult cats and dogs
•Cats and Dogs with food sensitivies
•Cats and Dogs with adverse food reactions due to food allergy or intolerance
•Cats and Dogs with food-related skin irritation

When should you consider Therapeutic Veterinary Diets?

Therapeutic vet diets are recommended for use once your pet has a diagnosed medical condition that would benefit from tailored nutrition. Typically introduced following diagnosis (e.g. pancreatitis), these diets are especially helpful for chronic digestive issues as they can help with common signs of digestive issues and reduce the risk of future flare-ups. Your vet may recommend a therapeutic vet diet alone or in conjunction with other treatments.

If retail diets have failed to improve symptoms or if symptoms recur, a therapeutic diet may be recommended. Therapeutic diets are nutritionally complete and balanced, allowing pets with chronic digestive issues to remain on them long-term under veterinary supervision.

For pets with acute gastrointestinal signs, like vomiting or diarrhoea due to dietary indiscretion (i.e. eating something they shouldn’t), short-term use of a therapeutic diet such as Hill's i/d Digestive Care may suffice until symptoms resolve, followed by a gradual return to the regular diet under veterinary guidance.

Your pet's treating veterinarian can provide tailored advice on nutrition based on your pet's specific needs and medical history. They will provide a detailed plan for your pet and let you know the best time to introduce the therapeutic vet diet.

Transitioning to a Therapeutic Diet

When introducing your pet to a therapeutic diet, do so gradually over the course of 7 days to avoid any tummy upsets. We recommend keeping approximately a week's worth of your old food in reserve for this.

    We recommend the following:

  • Day 1-2: Mix 25% of the new food with 75% of the old food.
  • Day 3-4: Mix 50% of the new food with 50% of the old food.
  • Day 5-6: Mix 75% of the new food with 25% of the old food.
  • Day 7 onwards: Feed 100% of the new food.

It's not uncommon for picky eaters to turn their nose up at something new, and by introducing a new food slowly this helps increase their acceptance of it. Other ways to help tempt fussy pets to accept their new food include mixing the kibble with some warm water, mixing in some therapeutic wet food, and heating the wet food in the microwave for a short burst to help improve the flavour and release a strong aroma that pets love.

To help make the transition as smooth as possible, maintain a regular feeding routine and use the same bowl placed in the same area, at the same times each day. Also, make sure that all members of your household are aware and on board with your pet's new diet plan, as unfortunately a lack of compliance is a common reason for dietary treatment failures.

When doing a food trial for pets with gastrointestinal disease, you should generally expect to see symptoms improve within 2-4 weeks of feeding the therapeutic diet solely, although this can vary between individuals. If you are not seeing improvement after that time, please consult with your pet's treating veterinarian to see if another type of diet is indicated.

For more information, read our handy article: How to Introduce a New Food to Your Pet.

Further Reading

Your Dog's Digestive System Explained

Best Sensitive Stomach Food for Pets

How To Make Dental Care Easier

Tick Paralysis in Dogs and Cats

How To Make Travelling Less Stressful For Cats

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