Sunday, June 21, 2009

New perspectives on 2 tough feline problems

At the American College of Veterinary Internal Medicine meeting 2 weeks ago, I spent some time in the poster sessions, which are brief communications about new research. It's important to keep in mind when reading these projects that these are preliminary communications and haven't undergone peer review in their expanded forms; nonetheless, they are sometimes harbingers of things to come.

There were some great posters, like the one that showed that GFR (glomerular filtration rate or the kidney's waste elimination function) is different between different breeds (just as we know that digestibility of food is different and many other breed differences).

But one that interested me was the ongoing work showing that cats with asthma may benefit from hyposensitization injections. Let's back up - asthma is an allergic response, centered in the lungs, to an allergen. In children, food allergy is a major concern but in adults, this is usually an environmental allergen although other triggers include pollution, exercise and infections. We presume the same triggers affect cats.

For other allergic signs such as itching, we identify the allergens using skin testing and treat it (with about 75% success) with allergy shots. So why not approach asthma the same way? This was the thinking behind the project. Unfortunately, these cats were rendered asthmatic experimentally and the project was not designed to show clinical benefit, measuring only immunologic markers of improvement. But improvement there was. And I've heard of at least one veterinarian who swore that allergy shots saved his cat's life.

So if your cat is asthmatic, will allergy testing and shots cause harm? We don't know, but depending on the severity of the cat's problem, you may be desperate enough to try it.

Also related to cats is a recent report from the ICA update, the news magazine of the Interstitial Cystitis Association, summarized here: http://www.medicalnewstoday.com/articles/154701.php

Websites about IC have long talked about food triggers but always acknowledge the controversial nature of the food connection. This article suggests that up to 40% of one doctor's IC patients have food allergies, but there may be a larger population who are sensitive to environmental allergens as well. Doctors who shared certain patients were noticicng that as their environmental allergies (known as atopy) were treated, the symptoms of IC were improving as well. This has inspired new studies to better define the link and potential for treatment.

So again - do we skin test and administer allergy shots to IC? The most well known researchers on feline IC would probably say no, as they would consider an experimental procedure yet another stress, which is now considered the most well understood cause of feline IC. In fact, this group would probably also argue that a food allergy trial (using an elimination diet containing ingredients that are novel to the cat) is enough of a stress to avoid in an IC patient.

I'm not sure this is a well enough proven concept to prevent me from doing a food trial in a gentle, gradual matter in these guys. But we do have another route to take if food allergy is playing a part, and that is to treat "leaky gut". We know that many allergy patients have a hyperpermeable intestinal tract, allowing exposure of the immune system to too many normal components of the gut. At the very least, probiotic therapy may be worthwhile because probiotics can reduce permeability and inflammation in the gut. Oh by the way, probiotics are being intensely studied right now in the treatment of atopic disease (or environmental allergies).

Just some thoughts to consider if your cat has one of these tough to treat chronic diseases.

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