Inflammatory Bowel Disease Part 3

Posted by Aaron

Friday, March 5, 2010

So what do I do if an owner can only do items one, two, and three on my diagnostic list? We treat presumptively. Then we rely on response to therapy to try and dial in on a diagnosis.

Maybe we change to a hypoallergenic diet. I'm a fan of the Royal Canin Hypoallergenic, but the novel protein diets like Venison and Potato are great ideas. They also have a product called Intestinal HE which can be fantastic for some chronic mal-digestion cases or during the healing phase of a severe gastroenteritis. It's a rich food, so it's not appropriate for long-term use in patients where obesity is an issue.

Maybe we treat with a broad spectrum de-wormer. Maybe we use an antimicrobial (like metronidazole) to help get bacterial populations under control. Maybe we use a pro-biotic or pre-biotic. Maybe we are able to get good enough response with these treatments and we can stop there.

Or maybe we don't.

If we want the answers then we move to the next step. Don't shy away from biopsy just because it sounds scary. It really is critical to making a good diagnosis.

Steroid use is something that should be considered ONLY after we have have ruled out as much as we can or as much as we can afford. Steroid trials can be a great diagnostic tool, but we have to keep in mind that LOTS of stuff will respond to steroids. Just because there is inflammation that responds to steroid doesn't mean that we know what has triggered it. Wouldn't we feel silly if we treat with a steroid and get a response only to find out later that the cat has hookwork infection or giardia and we just never did a proper exam to find that out!

Another unfortunately common error is to send a dog for colonoscopy for chronic large bowel diarrhea only to find out that there are whipworms causing the problem and we did a poor job or properly diagnosing them or failing to treat them. Don't jump ahead. Follow the advice of your veterinarian, work stepwise. If your veterinarian asks you to submit yet another sample of stool don't respond with, "If you didn't find it before, I'm not paying for you to not find it again." Remember that it often times takes multiple attempts to find a parasite. It's a ton cheaper to do another fecal exam and treat with fenbendazole (Panacur) than it is to jump to endoscopy.

Fire off questions to me. This is a long topic and I've hopefully not made it too confusing. I'd love to hear questions if there's something that doesn't make sense.


Inflammatory Bowel Disease part 2

Posted by Aaron

Thursday, March 4, 2010

Here's how I approach a case of chronic vomiting or diarrhea and what would be required to answer ALL possible answers. Think through this list when you go to your veterinarian (starting at item one - don't skip ahead) and it can help aid in the diagnosis tremendously - ESPECIALLY the historical findings.
  1. First things first - a good history. When does the diarrhea and vomiting happen? Is there any kind of temporal connection? Travel? Diet change? What about weight loss or gain? Is the vomiting immediately after a meal? First thing in the morning on an empty stomach? Is the diarrhea characterized by sudden urgency or constant straining? Did the vomiting or diarrhea respond to previous treatments? If so, what treatments and in what way did it respond? Did the problem resolve and then recur, or did it only resolve while ON the medications? What other medications is the patient on? What foods do the other animals in the house eat? Does this pet eat the other pet's food (either before it's eaten or after it's pooped out - IOW is your dog a poo-eater?)? Is your pet also having urinary problems? What breed(s) is your pet? All of these things help narrow down the list of likely suspects.
  2. Physical exam. Weight gain? Weight loss? How does the abdomen feel on palpation? Is the pet dehydrated? How does the patient "as a whole" look? Does the patient have other diagnosed problems that could be causing this problem? Are there any lumps or bumps that would cause concern? How does the anus and rectum feel on examination? Is there lots of gas? Constipation?
  3. Examine the poo. As was said on one of the funniest episodes of the sitcom Scrubs, "If you want to know what's wrong with you, it all comes down to Number 2!" Seriously, though, the poo can tell us a lot. This would be the best way for us to identify most parasites. Not all parasites can be found at all times, and fecal exams are never 100% sensitive. Repeat fecal exams at different times and on GOOD SIZED samples is critical. I get totally chapped when I see people take these little, itty, bitty, tiny samples and then declare that "the fecal is negative." NO NO NO. You must take a good sized sample, use good technique in your fecal examination, and then you can declare that "no parasites were seen." Seems like I'm splitting gnat weenie hairs, but it's a big distinction. No whipworms today doesn't mean much. They're a booger to find on a good day. Most would agree that you need a total of 5 fecals done on 5 different days to say that there are no whips present. Many times, submitting the stool to the lab for advanced diagnostics is smart. The labs can now look for parasite DNA in many cases and this makes the test very sensitive. You still have to submit a LARGE ENOUGH sample. You want to know how to make your veterinarian's job easier and help get a proper diagnosis? Bring stool with you! Fresh, stinky, warm poo makes me happy to see. Now I've got a big sample and I don't have to go fishing for it. It drives me crazy when someone come in with a complaint of stool problems, but then doesn't bring a sample.
  4. Basic blood workup. Look at my previous post on this one. We're looking for things like increased eosinophils (allergic reaction), low albumin (loss of protein), changes in cholesterol (poor absorption), abnormal lipids (funky fat absorption) and such.
  5. Gastrointestinal specific bloods include things like a "pancreatitis test" also known as a Spec cPL, Trypsin Like Immunoactivity (TLI), cobalamine, and thiamine. These each help identify if there is evidence of chronic mal-absorption and tell us more about if the pancreas is functioning normally.
  6. Endoscopy or abdominal exploratory surgery. The idea here is that we may need to LOOK at the gut and take biopsies to get a diagnosis. Endoscopy/colonoscopy is where we drive a camera down or up (depending on the end you start at :) ) and it allows you to see the lining of the gut. You can look for ulcerations, polyps, thickening, and any number of abnormalities. You can also use a little biopsy tool to take a tiny piece of the lining of the gut. The major benefits of endoscopy are 1) You get to see the inside of the gut up close and personal, 2) you don't have to open up the abdomen, and 3) it gives you nice biopsy samples that are only partial thickness - there's less of a defect to heal. The major downsides are 1) you can only get SO far down or up before you just can't get any farther with the camera. This means that there are large lengths of bowel you can't see. You will, therefore, totally miss problems if they are segmental and the segment that's a problem is out of reach. 2) the biopsy taken is only partial thickness. This means that you miss some of the deeper tissues. You may, therefore, miss out on part of the diagnosis. However, it should be noted that endoscopic biopsy is nearly always diagnostic, but it's not 100%. The major benefit of abdominal explore is that you can run the ENTIRE gut and can take full-thickness biopsy. The major disadvantages are that you can't see the INSIDE of the gut (major disadvantage), and you actually have to open up the belly (not a huge deal, but there is more healing involved).
  7. There is NO way to diagnose IBD properly without biopsy samples. IBD is a diagnosis made using the microscope AND the rest of the physical exam and bloodwork findings. Biopsy is also the only way to try and differentiate between things like lymphocytic lymphoma (tumor in the gut) and true lymphoplasmacytic inflammatory bowel disease in cats. In other words, is this cancer or is this just inflammation.
  8. Ultrasound of the abdomen. This can be considered in lieu of the endoscopy or explore, but it isn't the kind of thing that allows you to visualize how the inside of the gut looks and it is impossible to get biopsy samples of the gut. You can often times get aspirates and those may be diagnostic. Ultrasound is typically used if we have a patient that is a poor anesthesia risk or if we happen to be ultrasounding for some other reason and can try to get information on the gut as well. Ultrasound does have a great benefit from being able to measure the thickness of the bowel.
  9. Bacterial cultures of the gut. These have varied applications. There are lots of arguments both for and against cultures and what they mean. If I find salmonella, is that bad? Just how many bacteria in the small bowel are TOO many? If I don't find campylobacter on a culture, does that mean it's not there? I believe that bacterial cultures aren't used as much as they could be because we don't always know what to do with the results.
Do I expect an owner to be willing or able to do ALL 9 of these items? Nope. Most people flat out can't even consider it. In fact, it's overkill to even try and do all 9 items at once. We may eventually get through all 9, but we always start with the first few, then treat, then think, then move forward.

Next post - treatment options.


Inflammatory Bowel Disease Part 1

Posted by Aaron

Wednesday, March 3, 2010

As I started writing this, I began to wonder why it is I seem to spend so much time talking about poop. I pondered the poop for a while and have determined that I am not, in fact, obsessed with the tailpipe. Vomiting and diarrhea are far and away one of the most common complaints we see. I can't decide if scratching/itching/ears are more common or it it's vomiting/diarrhea. So although I may seem to blog often on puke and poo, there's a reason. It's what I see all day :)

I wanted to discuss IBD because it is probably one of the most abused diagnoses I see. I'm guilty of it as well. Basically, if we can't identify specifically what's going on and it's a chronic problem, we like to label it IBD. It's easy. It's only three letters.

The total post became too long, so I've decided to break it up into three parts. Today's post is talking about what causes IBD. Tomorrow will be how to diagnose. Friday's post will be treatment options.

So what is REAL Inflammatory Bowel Disease? In its purest sense, it is EXACTLY that. But it's not that simple. (Nothing ever is, right?) Keep in mind that your gut has more surface area (by FAR) than does your skin. By default, this means that there is quite a bit of your immune system involved in policing the surface area of the gut. So let's go back to the basics. What causes inflammation?
  • Parasites. giardia, coccidia, cryptosporidium, hookworks, and whipworms start the list. These parasites each attack separate portions of the gut and their specific symptoms depend of severity. The moral of the story is that they body react to a parasite and there is inflammation generated at the site of parasitic infection. Imagine the mosquito bite or the cut/scratch you see on your skin. Imagine that same thing happening (albeit microscopically) in the gut. Same idea.
  • Dietary problems. True food allergy is a major cause of IBD and it is, IMHO, one of the more common problems. Food allergies can be insidious and kind of "creep up" on you. Owners say, "he's always eaten this food so it can't be food allergy." Nope, wrong. Food allergies almost always develop over time after chronic exposure to the same protein. Meat proteins are more likely to be the culprit. Folks like to blame grains. From what we understand now, grains are less frequently a problem than are the major meat proteins. In other words, beef, chicken, eggs, soy are more likely a problem than corn, wheat, barley, or rice. The other really important point about diet is that abrupt CHANGES in diet can also trigger inflammation. If your body is not adjusted to digesting a particular food, it can cause incomplete digestion and this can trigger issues like bacterial overgrowths or excessive stimulation of gut contractions.
  • Stress. This is more a problem in people than in pets, but I think more cats are affected by stress than we truly appreciate. Chronic stress causes chronic increases in stress hormones like cortisol. There are also increases in the body's autonomic nervous system and you get increases in epinephrine and norepinephrine (adrenalin). These nervous signals cause changes in gut motility. Parts of the gut may contract more than they should, others may not contract at all. The result is poor digestion, unpredictable absorption of nutrients, and inappropriate populations of bacterial growth.
  • Bacterial overgrowth. This is very hard to prove. You are covered from head to toe in bacteria and your intestines are no exception. The balance of bacteria in the gut plays a big role in how "happy" your gut is and how well you digest your food. There are "good bacteria" that play a positive role in your immune response, and there are "bad bacteria" that tend to generate lots of upset.
Now you see why a simple diagnosis of IBD isn't so simple? Do you also see why it is often easier to just label the problem IBD and not try to figure out EXACTLY what is causing the problem?

The even more confusing part (and you may have been thinking of this as you read through the list above) is that problems listed above are rarely mutually exclusive. Food indigestibility can be caused by the presence of a parasite and the bacterial overgrowth that occurs with the indigestion is what causes much of the symptom. It's rarely as simple as problem 1 causes symptom A and so we treat for problem 1 and it all goes away. It's the onion analogy. We have to start peeling back the layers to get to the bottom of it.

Tomorrow - Diagnosis.