What is IBD?

Inflammatory Bowel Disease (IBD) refers to a group of disorders that cause long-term inflammation in the wall of the gut and persistent or recurrent gastrointestinal signs. IBD is a commonly diagnosed cause of chronic vomiting and diarrhoea in dogs and cats and can also be associated with a range of other symptoms.

The condition involves the accumulation of large amounts of inflammatory cells in the wall of the intestines (and sometimes in the stomach as well) which results in the disruption of normal digestive processes and absorption of nutrients. IBD is thought to be caused by a number of factors including environment, diet, genetics, microbiome (bacteria and other microbes that live in the gut) and the immune system. The most similar condition in humans is Crohn's disease.

Inflammatory Bowel Treatment at VSS
Inflammatory Bowel Treatment at VSS

Common signs of IBD are

  • Chronic vomiting (may be waxing and waning over weeks or months)

  • Chronic diarrhoea

  • Loss of appetite

  • Bloating

  • Abdominal pain

Less common signs include

  • Weight loss

  • Blood in stools (which may be visible or microscopic)

  • Vitamin B12 (Cobalamin) deficiency

  • Lethargy/malaise

  • Increased flatulence

  • Behavioural changes

  • Intermittent pain episodes (e.g. prayer posture)

  • Accumulation of fluid in the abdomen or other spaces in the body if protein levels drop too low

Diagnosis of IBD

A clinical diagnosis of IBD relies on several conditions being met:

  • Gastrointestinal (GI) signs that occur chronically (over a period of at least 3 weeks or more)

  • Exclusion of infectious or other causes of GI signs

  • Evidence of inflammation in gut tissues demonstrated on biopsies

In the absence of biopsies to confirm the presence of inflammation in the gut, these disorders may also be referred to as chronic enteropathies.

There are many reasons your pet may present to a veterinary clinic for vomiting and diarrhoea so other conditions need to be ruled out before considering treatments for IBD.

Some of the tests used to investigate GI signs may include:

  • Screening blood tests (usually consisting of a complete blood count and general biochemistry panel) - This may help investigate for other causes of vomiting and diarrhoea in your pet such as kidney or liver disease. These tests may also reveal changes that may be a result of chronic vomiting or diarrhoea, such as low protein levels.

  • Additional specific blood tests may also be suggested:

o   Cortisol levels or a full ACTH stimulation test may be needed to rule out a condition called Addison's Disease, a hormone disorder that can mimic the symptoms of IBD. Addison’s (also known as hypoadrenocorticism) requires targeted treatment different to that used for chronic enteropathies.

o   Testing the blood for Vitamin B12 (otherwise known as cobalamin) may also be recommended. Many patients with chronic GI disease can be low in this vitamin and gut healing may be delayed or prevented if low levels persist. Supplementation with oral tablets or injections will be recommended if your pet’s levels are too low.

  • Faecal testing - parasites or intestinal worms can be a cause of abdominal upset and may occur even if patients are thought to receive regular worming prevention. Faecal samples can also be analysed for evidence of infection with particular bacterial pathogens so that appropriate antibiotics can be prescribed, if indicated.

  • Abdominal ultrasound - this is a non-invasive test that involves the use of sound waves to investigate for any structural changes to the abdominal organs. While the GI tract is focused on to determine if any focal masses or changes in the layering of the wall can be observed, all other abdominal organs are assessed as well. Often in IBD patients this scan returns normal results but it can be useful to rule out any problems that may require different intervention (such as surgery to remove an intestinal foreign body or a mass). Additional information on ultrasound at VSS can be found at

  • A treatment trial with multi-day use of an anti-parasitic medication will also be used to further rule out worms or parasites that may not always be apparent on faecal testing. A few days’ treatment with an inexpensive, low-risk medication is strongly recommended before progressing to more invasive testing.

If no diagnosis is reached with the initial tests, your vet will often consider a food trial with a special diet as the next step.

Dietary manipulations are important to try as studies have shown that many pets will respond to strict diet changes without further intervention needed. Animals that show improvement after diet trials are said to have a Food Responsive Enteropathy (FRE). There are many options for types of foods, additives and diets that can be used to see if they benefit your pet. They may include:

  • Low fat foods. (e.g. Royal Canin GIT low fat, Hills low fat)

  • Dietary changes designed to alter the types or amounts of microbes that live in their gut (referred to collectively as the ‘microbiome’). This may include

o   specific foods such Hills Gastrointestinal Biome

o   the addition of probiotics (e.g. Fortiflora)

o   altering fibre intake (e.g. by adding pumpkin, psyllium husk or Metamucil).

  • Hydrolysed protein diets: 

o   These are foods that aim to limit the body’s recognition of proteins that commonly cause allergies in dogs and cats (e.g. Hills z/d, Royal Canin hypoallergenic, Purina HA).

  • Novel protein diets:

o   These are diets that are designed to provide proteins (and in some cases, carbohydrates) that pets have not been fed previously to prevent the body from reacting to them.

o   There are many options for commercially available diets that have been formulated to be complete and balanced for your pet (E.g. Prime 100 comes in many protein varieties such as salmon, wild boar, duck or crocodile; Royal Canin also has a duck and potato diet)

o   In some cases, elimination diets focusing on just one or two ingredients are trialled until symptoms improve. Once the gut has recovered sufficiently, foods are added back in until a long-term complete and balanced diet that the pet will tolerate can be achieved.

  • If home-prepared diets are preferred to commercially available ones, a consultation can be arranged with a veterinary nutritionist to design a custom diet for your pet’s individual needs.

It is very important that during a food trial the recommended diet is the ONLY thing that the pet consumes. Any access to other foods has the potential to reintroduce an allergic reaction and additional inflammation, or reduce the effectiveness of microbiome-altering additives. This will likely cause the recurrence of GI signs.

We generally expect to see a response within 2 weeks of starting a diet change but maximal response is seen within 4-6 weeks. It is important to remember this is a diet TRIAL, and food changes are not a one-size-fits-all approach. As reactions can be unique to each individual, it is sometimes necessary to work through a number of diets before a suitable one is found to control your pet’s symptoms. In some cases, once your pet is in remission it may be possible to reintroduce some food types without flare-ups.  But for other patients, they may need to remain on a specialised or very restrictive diet life-long.

When on these diets it’s important to avoid any flavoured food products in addition to treats. This includes all chews, rawhides, treats, and sometimes even flea/tick prevention. Please speak to your veterinarian about topical or unflavoured parasite prevention if your pet is on a strict food trial.

What if my pet doesn’t respond to these diet interventions?

Additional treatment trials may include adding in antibiotics such as metronidazole or tylosin. Animals that do not respond to food changes but improve with the use of antibiotics may be classified as having an antibiotic-responsive enteropathy (ARE). In general, animals that have FRE tend to have a better prognosis than those with ARE. While antibiotics are required to control symptoms in some cases, long-term antibiotic use may result in complications due to the development of resistance or adverse medication effects.

Additional testing?

Gastrointestinal biopsies are recommended if treatment trials are not successful. Biopsies allow microscopic examination of the tissues present in the wall of the GI tract (a process called histology) which may show evidence of inflammation, ulceration, or invasion of cancerous cells.

Biopsies can only be obtained through procedures that require a general anaesthetic. There are two options for biopsy collection:

  • Endoscopic biopsies are a less-invasive option that allow small samples of the innermost lining of the stomach, first part of the small intestine and colon to be collected through the use of a flexible endoscope. Recovery time is usually quick after an upper or lower GI (colonoscopy) endoscopic procedure. The biopsies obtained only sample a small portion of the gut and stomach wall, but in many cases, can be representative of GI disease without having to resort to surgery. Additional information on endoscopy at VSS can be found at

  • Surgical biopsies can sample the large central portion of the intestines that cannot be reached endoscopically, and can obtain full-thickness biopsies which may show changes in deeper tissue layers that endoscopic biopsies can’t. Surgical approaches are more invasive, and the trade-off for larger samples is the longer recovery time post-procedure. Animals can often be discharged the day after surgery if there are no complications, but must be kept quiet for at least 10-14 days after their procedure while they heal from their incisions.

Other treatment options

If your animal is not responding to diets or further interventions, medications that suppress or modify the immune system may be required. Options can include budesonide, cyclosporine, dexamethasone or prednisolone. Some patients may not respond to one treatment but improve on another. Due to their significant effect on the immune-system and potential for adverse effects, it is usually recommended that GI inflammation be documented through biopsies before these medications are used. A positive response to this therapy means your pet would be classified as having an immunosuppressive responsive enteropathy (IRE).

Prognosis of IBD

IBD generally can’t be cured but in many instances symptoms can be controlled, improving quality of life for pets and owners.

Working through the diagnostic and treatment approaches for chronic GI symptoms requires substantial commitment from owners. The goal is to improve symptoms in the least invasive ways with the least potential for adverse effects.

Some pets experience disease that is difficult to control by any means. Fortunately, those with non-responsive enteropathies (NRE) are the exception rather than the rule when it comes to chronic GI symptoms and IBD. Studies show that most pets can show improvement with the right treatment. However, even well-controlled pets can experience flare-ups from time to time. Your veterinary team is here to help you through all steps of your pet’s management.

The most important thing to remember about IBD is that it’s a trial-and-monitor type of disease with regards to treatment. There is no perfect formula that will work for every case and often a combination of management strategies are needed, which may include diet, supplement, antibiotic and/or immunosuppressive interventions. Improvements are likely in time, and patience is required to ensure we achieve the right diagnosis and treatment for your beloved animal.

Would you like more information about patient care from VSS?

Here are links to additional resources that may be useful to assist in the home care of selected pets after discharge:


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