Azodyl for Kidney Failure in Cats: An Update on the Evidence

In a recent article about pet supplements for the Science-Based Medicine Blog, I reviewed the dietary supplement Azodyl, marketed for kidney failure in dogs and cats. At the time, the evidence I was able to find was extremely limited, poorly controlled, and subject to a high risk of bias due to association of the research with the company marketing the products. My conclusion was that the theory behind the product was weakly plausible and the evidence insufficient to justify a firm conclusion about efficacy.

An abstract is being presented at the upcoming American College of Veterinary Internal Medicine Forum which reports the results of a controlled study on the use of this product in 10 cats with  chronic kidney disease.

M. Rishniw; S. Wynn
Azodyl Fails to Reduce Azotemia in Cats with Chronic Kidney Disease (CKD) When Sprinkled Onto Food 

The study examined whether there was any difference between commonly measured blood markers of kidney disease, blood urea nitrogen (BUN) and creatinine, in cats given Azodyl and cats given a placebo. The Azodyl was sprinkled on the food since this is commonly how the product is used (making cats take capsules is often difficult). The study was randomized, double blinded, and placebo controlled. The criteria for confirming a positive effect were quite generous, however no difference was found between cats given Azodyl and cats given the palcebo.

The authors concluded:

Based on these results, Azodyl, applied by sprinkling onto food fails to reduce [BUN and creatinin] in cats with [chronic kidney disease]. Whether intact capsule administration reduces reduces azotemia in cats with [chronic kidney disease] remains unknown.

Though generally well-designed, this study was small, and of course single studies are almost never sufficient to provide the final word on a particular therapy. The issue of potential bias for or against a hypothesis is always hard to evaluate objectively, but I am unaware of any direct funding or other involvement of the company in this study. I do know that one of the authors, Dr. Susan Wynn, is a prominent researcher and advocate in the area of herbal and some other alternative therapies, so she certainly would not be expected to have a bias against the product. And negative findings in clinical research are inherently more reliable than positive findings because our studies and our psychology are designed to confirm our beliefs rather than refute them. So while the case is by no means closed, the balance of the very limited evidence is currently against any significant clinical value for this product.

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103 Responses to Azodyl for Kidney Failure in Cats: An Update on the Evidence

  1. JethroT says:

    Hello…I have an 18 year old cat, Molly, who was recently diagnosed with Kidney “failure” which seemed an odd diagnosis to me as I would think kidney failure would mean death. Anyhow….she was prescribed with Azodyl and Methimalzole for this condition. Like most others in here have suggested it is almost impossible giving her the capsule. I have done many studies and watched you tube videos of Vets making pilling your cat easy, it is certainly not that with Molly. She takes the Methimalzole whole in a pill pocket, no problem, but simply refuses the capsule. I have tried removing the contents of the capsule and sprinkling it on food, or adding it to a little milk and putting it in a syringe. Now I see from comments in this blog that unless it is given as a capsule, Azodyl is worthless. I am due for a follow up visit to the vet this week.
    Does anyone know of a liquid alternative?

  2. skeptvet says:

    Methimazole is for thyroid disease, not kidney disease, and it is important to follow up with your vet to make sure your cat responds appropriately and the dose is adjusted to his or her needs. Too much can make the kidney problem worse, so this monitoring is important.

    The term “kidney failure” is pretty imprecise and old-fashioned. We now grade the severity of chronic kidney disease according to a standard scale which is then used to guide management, so again make sure you are clear with your vet about what stage your cat has and if all the right factors are being monitored and managed (bloodwork values, blood pressure, protein in the urine, etc).

    There is no evidence to suggest any kind of probiotic is going to make a difference, so I would not waste time and energy and money looking for an alternative to Azodyl, which almost certainly doesn’t work anyway.

  3. DrDEq says:

    I am an equine veterinarian who owns a CRF cat, now a year out from his diagnosis. He is 14. In that year, I have updated my knowledge of feline renal disease, as well as living it day to day. I have found a few things that might be helpful. First, for allergic cats. Royal Canin makes a renal support, hydrolyzed protein kibble. My cat is very allergic and lived on Hill’s Z/D for much of his life. He would eat, but could not tolerate, any of Hill’s renal foods. I turned to the Royal Canin hydrolyzed protein first, but then discovered by trial and error that he can eat any/all of the Royal Canin renal support foods, kibble or canned. So, before you turn to nutritionist-formulated diets (that’s a lot of work), it might be worth giving RC a try. Second, constipation. My guy has periodic issues with this and will back off eating and generally feel less well. I have started adding acacia fiber powder to his food. (Renew Life makes an organic one that is very nice.) It is soluble and tasteless (I became acquainted with it while doing a smoothie diet myself. I can personally attest to the lack of taste.) He prefers his kibble mixed with a little water and microwaved (gently, please) to form a sort of “gravy train” result. I add the acacia fiber to this mixture and it dissolves and he laps it up. Added benefit of getting a little extra water in him as he isn’t in love with wet food. Giving him this mixture (about 1/8 tsp per serving or as tolerated) 2-3X daily has pretty much resolved the constipation problem. If stools get a little too soft, cut back on the amount slightly. Third, subQ fluids. I learned from a blogger to try thin-wall needles. They have a larger inner diameter for the same outer diameter. I am currently using 21 gauge and am thinking of going to 22g. The fluids take less than 5 minutes to run in (100-125ml) and he is much happier than with the larger gauge needles. Fourth – probiotics. I have not tried any of these products on my cat. I once gave him one dose of Dasuquin for his joints and it took me a week to get him straightened out after vomiting and all manner of GI upset. So, tread lightly with some of these dietary additives. On the other hand, the more I learn about the GI microbiome, the less I feel that I know, so if your cat feels better when you give the probiotic AND the cost doesn’t prevent giving him something that we KNOW works AND you don’t have to compromise your relationship to administer it, I would not say no. But that’s a lot of qualifiers. Fifth – there is a paper that I have found most helpful. It may be way technical for many, but if you are into trying to read good information read through the ISFM Consensus Guidelines on the Diagnosis and Management of Feline Chronic Kidney Disease. Tried and true evaluation and recommendation of options for all the nuances of CRF by a panel of experts in the field. So, to all of you CRF cat owners/lovers out there, I am one of you, but we must also keep in mind that this is not about us. This is about the well-being of the cats. CRF is a terminal disease, but then so is life, so try to see the glass as half full and just enjoy your beloved kitties while you can. Think quality over quantity. It’s not about how long you can keep them alive. It’s about how well they can be while they are alive. And they don’t fret about it like we do. They don’t know they have renal failure. They just wake up every morning (noon, or night) and proceed with their day, so try not to mar that precious innocence more than necessary in the name of not having to say good-bye for another day/week/month. And thanks to all of you for your devotion to these incredible little guys. Our world is a better place because of them. And you.

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