Myles McKenna starts off this weeks members webinar about canine IBD with a great overview slide. He’s highly qualified with plenty of letters behind his name: MVB MVetSci MVetMed DACVIM (SAIM) DECVIM-CA MRCVS. We’ve had the pleasure of hosting previous webinars twice, and we have another four lined up! The topics range from polyarthritis to insulinomas, but this webinar was strictly focused on IBD. That is, inflammatory bowel disease. We’ve all seen it in practice and Myles covers the approach to the ‘normal’ case and the approach to the refractory case as well.
An Irritating Bowel Disease
The first slide or two of the webinar outlines the pathophysiology of chronic enteropathies, defining chronic as a duration of >3 weeks. It also (importantly) notes that the diagnosis of IBD is essentially a diagnosis of exclusion. This is the exclusion of any other cause of the clinical signs that you’re seeing, whether that’s large bowel diarrhoea or vomiting. You can further classify the type of IBD into three subcategories based on their causes. We’ll go into that later.
There was a quick pathophysiology tutorial which I found really simply put and really easy to pick up. I have trouble putting the pathophysiology together sometimes, but with the slides and Myles’ patient explanation, canine IBD suddenly made sense.
The mechanism is something like this:
In the intestines of the animal (and us as well), there’s a microbiome. The body has to have a way of determining what the commensals are, so that we don’t react to them. This is mediated by pattern-recognition receptors on epithelial and non-epithelial cells in the gut. Antigens of commensal bacteria are detected by these receptors, which are then presented to regulatory T cells. Regulatory T cells then secrete anti-inflammatory factors. It’s a delicate balance, but it makes sure that there is no inflammatory response to normal organisms. In cases of chronic enteropathies the normal immune tolerance is lost, and in chronic inflammation the mucosal barrier starts to break down which contributes to this cycle of inflammation.
Keeping our gut bacteria happy
Canine IBD, as mentioned above, can be split into three subcategories.
In these cases, the animals react to a dietary component. We come across this very frequently in practice, and changing the diet to one with a novel protein source (like Hills DD) or a hydrolysed protein can help things get back to normal. Remembering, of course, that Fluffy is allowed no treats or flavoured medicines, and it takes a few weeks for you to really see an impact. Dr. McKenna makes a great point that unless the client is really unable to, a pre-made diet will always be superior to a homemade diet, which can predispose to mineral deficiencies. We also need to remember as practitioners not to always fall on this diagnosis! This is usually found in animals 1-2 years old, so if a scruffy 10 year old Westie comes in there may be a different underlying case.
In antibiotic responsive cases, the mucosal damage from inflammation and the subsequent flat malabsorption leads to an alteration of intestinal microflora. Its treatment quite self explanatory – antibiotics. We cover which ones to use in the webinar.
In these cases, the ‘true inflammatory bowel disease’ cases, clinical signs cannot be managed with diet or antibiotics alone. It requires immunosuppressive doses of steroids (and potentially a secondary drug as well), because the animals own immune system is the problem.
A Diagnostic Pathway
Non-critical cases of canine IBD
The clinical approach to canine IBD that Myles McKenna provides is probably one of the clearest that I’ve seen. So often we are presented approaches in university and further that aren’t practical as a first opinion practitioner.
The first step is ruling out extra gastrointestinal causes of vomiting and diarrhoea. This is done through an array of tests, all of which are available in first opinion practice. These tests are outlined in the webinar.
Our second step, which is really three steps, is to gradually rule out the causes of IBD. If the animal is stable (ie there’s no hypoproteinaemia), then you want to do a strict diet trial (+/- a cobalamin supplement if indicated). In cases of non-repsponse after a month, you add an antibiotic to the routine for the next 3-4 weeks. Specific antibiotics are mentioned in the webinar. Finally, if there’s no improvement then you resort to immunosuppression. Specific immunosuppressive agents are covered in the webinar, and believe it or not it actually ranges further than just Prednidale! Remember to biopsy before treatment though, to rule out lymhomas, lymphangectaesia etc.
Critical cases of canine IBD
Myles McKenna also covers what to do in cases that have really severe clinical signs – profound diarrhoea, hypoproteinaemia, and anorexia. Due to the faster progress of these cases, knowing the first steps in a critical setting is imperative. Especially since feeding may actually make things worse!
My treatment isn’t working!
The second half of the webinar covers refractory cases. The main questions that you need to ask yourself are as follows:
“Do I have the wrong diagnosis?
Is this individual variation?
Have there been changes in the microbiome?
Is parasitism involved?
Is this a refractory case?”
The ‘troubleshooting’ part of the webinar is in-depth but accessible. I know, it sounds contradictory but trust me on this one. I won’t cover all aspects in this blog because then I have no secrets, but I’m in full faith that if I followed this protocol in practice, no stone would be left unturned.
Myles presents us with a host of things to investigate and try when the cases just aren’t responding to treatment. These range from double-checking the diagnosis (and no, this doesn’t just mean running all the tests again) to fibre in the diet and even faecal transplant. Although, saying that, Myles does a good job of explaining that faecal transplants in dogs are still in their infancy. That being said, if there’s some evidence showing that it can lead to wonderful results, so watch this space.
All in All
This is one of the easiest to follow webinars that I’ve seen, and it was one that the hour absolutely sped by. The information is clearly laid out and although I definitely feel like I’ve learned through my hour, it doesn’t feel overwhelming. The clear schematics, slides, and ‘pathway’ feeling of the webinar really holds your hand as you walk through all elements of canine IBD in practice.
I’ve left quite a bit to the imagination in this blog, so check out the webinar here. It’s free to review for our Unlimited Members or you can get access for £40+VAT.
If you’d like to have a bit of a chat with other Vets, RVNs, and students then you can join our Facebook group. Think of it as an online coffee shop, where we share fun and interesting cases from about the internet and there’s some cheeky exclusive videos to come as well.
It was lovely to have you here today, happy watching! 🙂