Inflammatory Bowel Disease (IBD)
This is not the same as Irritable Bowel Syndrome (IBS).
Why does this happen?
The full cause isn't known. Something stimulates the immune system and causes ongoing inflammation in the intestines. Possible triggers include parasites, toxic byproducts from bacteria living in the intestine, and food proteins.
IBD is a "diagnosis of exclusion"
There is no single test that confirms it. Instead, other diseases are ruled out one by one — and when they've all been excluded, the answer is IBD. This is why the diagnostic process below involves so many steps.
Why does my vet think my pet may have IBD?
A little vomiting or diarrhea here and there seems fairly standard for dogs and cats. Cats groom themselves and bring up hairballs; dogs eat all sorts of things they shouldn't. So the signal isn't any one episode — it's frequency.
Usually these patients don't seem obviously unwell. The signs are limited to the intestines:
- Vomiting, diarrhea, or both
- Gradual weight loss over time — nothing sudden
- Cleaning up hairballs or vomit more often than you did with previous pets. Vomiting more than once a month is not normal.
- Realising your pet hasn't passed a normal stool in weeks or months
How is IBD diagnosed?
Step one is checking all the other causes of intestinal disease.
Blood panels — four part
- Rule out widespread problems such as liver and kidney disease
- Pancreatitis and TLI — pancreatic inflammation, or trouble releasing digestive enzymes
- Hyperthyroidism — thyroid and metabolism problems
- Vitamin B12 and folate levels — problems absorbing nutrients through the intestines
Fecal testing
- Requires broad testing, especially in young pets or those with a history of being housed with multiple animals
- Needs PCR testing for Giardia, Cryptosporidium, Salmonella, Tritrichomonas, and Clostridium perfringens
Addison's disease screening (dogs only)
- Often causes symptoms that come and go
- Can produce several unrelated-looking symptoms at once — allergies, weakness or dizziness, trouble sleeping
- Known as "the Great Imitator" because it mimics so many other diseases
After ruling out other diseases
If those results come back normal or negative, the next step depends on how your pet is doing.
Path A
The unstable patient
If your pet isn't feeling well, is losing weight, has a poor appetite, or has low blood protein levels, there are two options to consider: referral, or a trial with medication.
In these patients the concern for lymphoma — cancer — is considerably higher, which is why moving quickly matters.
Path B
The stable patient
Further testing to identify the full extent of the problem: gallbladder sludge, which parts of the intestine or stomach are affected, whether the kidneys are aging too quickly, blood vessel issues, adrenal swelling, and possible cancer in the liver, intestines, kidneys, lymph nodes, or pancreas.
Alternatively, we may recommend starting the treatment trials below and assessing the response.
Comparing the diagnostic options
Ultrasound
Cannot completely rule cancer in or out.
Worth knowing: lymphoma is common in cats and can occur at any age.
Surgery
Can assess cancer, but doesn't assess other problems well.
Performed at a regular veterinary practice; more affordable; allows full intestinal assessment.
Endoscopy
Can assess cancer, but cannot assess other problems.
Performed at a specialty hospital; easier recovery for the patient; allows only partial intestinal assessment.
Treatment trials — three levels
Treatment is approached as a series of trials, working from the least invasive option upward.
Level 1
Food responsive IBD
With a normal albumin level and no vitamin B12 deficiency, there's roughly a 50:50 chance of responding to diet alone, with no medication needed.
Option 1 — hydrolyzed protein diets
The most consistent success. Hydrolyzed proteins are "predigested" into pieces too small to stimulate the immune system.
Option 2 — novel protein diets
Feeding an unusual protein the pet hasn't encountered before, such as rabbit, venison, or alligator.
Expect about a month to see a good response, with improvement starting in the first two weeks. Continue any medication until then.
Level 2
Antibiotic responsive IBD
Metronidazole or tylosin are often used to change the balance of intestinal bacteria.
- At least a two-week trial. If your pet shows good improvement, lifetime treatment may be needed.
- Metronidazole has some drawbacks with long-term use. Tylosin is widely used this way instead, though it's very bitter.
Level 3
Steroid responsive IBD
Stopping the inflammation by suppressing the immune system. Steroid treatment requires blood testing every six months.
- Corticosteroids (prednisone or prednisolone) — the strongest option. Long-term use in cats carries a risk of heart failure, so cats on steroids need careful monitoring.
- Budesonide — stays mostly within the intestines, acting on the lining directly with little absorbed into the bloodstream.
- Cyclosporine or chlorambucil — used in cases that don't respond to steroids alone.
Is your pet vomiting more than once a month?
That's worth investigating. IBD takes patience to diagnose, but it's very manageable once we know what we're dealing with.