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Ixnay on the IBD: An update on handling patients with chronic enteropathies
When it comes to chronic gastrointestinal cases, its time to throw out your outdated terms and diagnoses.
Photo: Getty Images. Illustration: Hannah Wagle. Calling all chronic enteropathies! Wait, are you calling all your chronic gastrointestinal (GI) cases inflammatory bowel disease, or IBD, without doing a histopath of the small intestine because the owner won't let you biopsy?
STOP IT. CVC educator Craig Ruaux, BVSc (Hons), PhD, MACVSc, DACVIM-SA, says the term “inflammatory bowel disease” is outdated. Even in the cost-conscious world of private practice, there are new, more rational ways to approach your chronic enteropathy patients than, “Let's just pull out the pred and see what happens” that provide a better standard of care and won't break the bank.
Add an “I” for idiopathic
When veterinary professionals discuss chronic enteropathies, the term IBD is thrown around quite a bit. But Dr. Ruaux thinks IBD is markedly overdiagnosed in chronic gastrointestinal cases and is being used as a catch-all term for any time the small intestine is inflamed. There are a lot of diseases outside of IBD that can cause small intestinal inflammation, he says, and the underlying pathology is very different than true IBD.
When it comes to IBD, idiopathic inflammatory bowel disease (IIBD) is a more accurate term, says Dr. Ruaux. IIBD is a diagnosis of exclusion. It implies you've done a complete workup, including a minimum database, a fecal flotation and GI panel, and acquisition of biopsy samples of the intestines. If not, your diagnosis is chronic enteropathy of unknown origin. Only diagnose something to the level with which you can describe it, Dr. Ruaux says.
Geez, those GI signs
Chronic enteropathies, regardless of the underlying cause, often present in a very similar manner, Dr. Ruaux says. Signs may include weight loss, lethargy, vomiting, diarrhea and appetite alterations-in dogs, at least.
Cats love to break all the rules. They often present polyphagic with large, voluminous diarrhea. They may also have steattorhea because chronically inflamed intestines lose the ability to absorb fat. Unabsorbed fat in the intestine stimulates diarrhea by osmotically drawing water into the lumen and by fostering an environment for the bacterial toxins. Cats with chronic enteropathy with steatorrhea that look like they have exocrine pancreatic insufficiency almost never do, Dr. Ruaux advises.
The deets on diagnostics
If this is the first time you are seeing a chronic enteropathy patient, Dr. Ruaux recommends starting with a complete blood count, serum chemistry profile, urinalysis, fecal flotation and GI panel, if the owner will let you. If you give a simple explanation of why you need these tests, such as, “We need to rule out causes outside the GI tract that cause diarrhea,” or “Knowing serum cobalamin and folate concentrations will help us determine the extent of the disease and guide appropriate treatment decisions,” you are more likely to get a yes to go ahead with diagnostics. Just remember to keep communication simple!
In cats, Dr. Ruaux recommends that the GI panel include trypsin-like immunoreactivity, cobalamin concentration, folate concentration, pancreatic lipase immunoreactivity, and Spec feline pancreas-specific lipase test. It is useful to know if cats with chronic diarrhea also have chronic pancreatitis, as that will influence your treatment decisions. Dr. Ruaux notes that the canine pancreas-specific lipase test is less important in chronic enteropathy canine patients unless they present with vomiting.
Need a reminder about why folate and cobalamin are important diagnostic markers? I did too. Folate is only absorbed from the duodenum and is decreased in cases of chronic duodenal mucosal inflammation. Cobalamin is only absorbed from the distal small intestine and is a very specific marker for distal ileal mucosal disease. Low cobalamin and folate concentrations are indicative of severe diffuse disease, and this will limit the efficacy of oral therapy for IIBD. Supplement with cobalamin and folate before instituting therapy, Dr. Ruaux says.
As results of a GI panel can take up to five days, Dr. Ruaux recommends performing an abdominal ultrasonographic examination to inspect intestinal wall thickness while you are waiting.
If an owner has financial constraints, Dr. Ruaux says forget the ultrasound and go straight to endoscopy or exploratory laparotomy and biopsy. While the ultrasonographic exam can tell you whether there is abnormal wall thickness, Dr. Ruaux finds abdominal ultrasonography has a low sensitivity and specificity for diagnosing GI disease, except in some cases of protein-losing enteropathy. Furthermore, doing an abdominal ultrasonographic examination does not change the diagnostic need for an intestinal biopsy, except in cases of very old or debilitated patients where anesthesia is a concern or patients with a palpable abdominal mass.
When it comes to choosing biopsy via exploratory laparotomy vs. endoscopy, Dr. Ruaux says it really only matters in cats with GI lymphoma. GI lymphoma is located in the ileum and you cannot reach the ileum with endoscopy unless you use a transcolonic approach. If you only sample from the proximal intestine, you may miss the disease.
Specifics on treating those nonspecifics
If histopathologic examination of the intestinal biopsy samples reveals nonspecific inflammation, Dr. Ruaux rules out lymphosarcoma and lymphatic drainage diseases. Infectious disease, intestinal dysbiosis, food responsive disease and IIBD all read as nonspecific inflammation. For nonspecific inflammation patients, Dr. Ruaux takes a five-step approach. These steps can still be followed if the client declines biopsy, as long as the client knows you are treating empirically.
Prescribe fenbendazole at 50 mg/kg for five days to treat for occult giardiasis or other intestinal parasitic infections.
Dr. Ruaux does not use metronidazole to treat giardiasis because he thinks that in order to successfully eliminate giardiasis, you must use doses that are toxic.
Treat any cobalamin or folate deficiencies.
Rule out a food-responsive enteropathy (FRE) by instituting a dietary modification trial.
Dr. Ruaux prefers using a novel protein diet over a hydrolyzed diet. If he can, he will also prescribe a low-fat diet because of fat's ability to cause osmotic diarrhea if it is unabsorbed from the lumen. More than 60% of cats with chronic enteropathy signs show improvement with diet modification, according to Dr. Ruaux, and don't need corticosteroids. Dogs with classical FRE tend to be younger, large-breed dogs and can respond well to diet modification therapy.
Even though he prefers diet trials to last four to six weeks, Dr. Ruaux says that if there is no improvement after two weeks, it is likely the animal will not respond. If the patient isn't responding to a hydrolyzed diet, it is still possible to have a FRE that is reactive to the underlying protein source in the hydrolyzed diet, and a novel protein source must be chosen. At this point, if the owner is tired of the diarrhea, it is appropriate to continue the diet trial and also move to step 4.
Rule out small intestinal bacterial overgrowth (SIBO) or antibiotic-responsive enteropathy with an antibiotic trial. Oh, and it's no longer called SIBO.
Dr. Ruaux says the more appropriate term is “intestinal dysbiosis.” SIBO implies that the patient's intestine has too many organisms or an overgrowth of pathogenic organisms. But in patients with chronic enteropathy, they tend to have a change in the GI microbome that is correlated with dysfunction. Time to join the cool kids and change up your terminology.
Dr. Ruaux continues the diet trial and adds in 20 to 25 mg/kg of tylosin twice daily for four to six weeks, as well as probiotics and prebiotics. For clients that feed raw food or home-cooked food to their pets, a prebiotic such as fructooligosaccharide powder can be purchased from the health food store and should constitute 1% of the diet, which comes out to 1 g powder/100 g of food fed. For those clients who find this cost-prohibitive, explain that prebiotics are formulated into GI therapeutic diets.
What about metronidazole? Dr. Ruaux only uses metronidazole for patients with stress colitis or sepsis. He prefers that his patients receive tylosin over metronidazole for treatment of chronic enteropathy.
No improvement? Time for corticosteroids.
If you are 21 days into the trial and the pet is not responding, it's time for corticosteroids and a diagnosis of IIBD. Dr. Ruaux prescribes 1 to 2 mg/kg prednisone (or prednisolone for a cat) per day. Pharmacokinetically, there is no difference between once-a-day and twice-a-day administration. If the patient is a dog that is not responsive and there is evidence of a protein-losing enteropathy, then Dr. Ruaux will add in chlorambucil to increase survival time.1
For intestinal dysbiosis, food-responsive enteropathy or true IIBD, client education is as important as diagnostics and therapy, Dr. Ruaux says. Stress to veterinary clients that you are managing the disease, not curing it, and it will take trial and error to both obtain a diagnosis and treat the problem, especially in patients that have more than one condition. Advise clients that the gut is chronically inflamed, and it takes time and testing to figure out the root cause or causes. Many clients have their own GI distress journeys, and I have found that they understand the diagnostics and treatments surprisingly well. Be hands-on with these patients in follow-ups-don't be afraid to schedule multiple rechecks. Most clients will appreciate your effort, and you will get better compliance in pursuing diagnostics and adhering to the diet trial and therapeutic recommendations.
1. Dandrieux JR, Noble PJ, Scase TJ, et al. Comparison of a chlorambucil-prednisolone combination with an azathioprine-prednisolone combination for treatment of chronic enteropathy with concurrent protein-losing enteropathy in dogs: 27 cases (2007-2010). J Am Vet Med Assoc 2013;242(12):1705-1714.