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

  1. This is what my vet told me as well.
    And tonight may well be the night of proof.
    That this when an older cat is diagnosed with KD…if they are stabilized and their Bun..and Creatin numbers become the “New normal”.. as is with my girl… that this medicine may help to manage the disease to allow the kitty more years of life.
    Not to lower numbers.

    I am just looking for any proven stories…and or any ..more important..side effects.
    As my Chloe just had her 3rd dise..after 2 days I thought I would lose her.
    Plze share with me.
    I am a wreck.
    My last baby lived to 20.

  2. dana nathanson says:

    I wrote a comment on 11/8. My Chloe is improving in a big way but seems to be constipated a bit. She is 17 yrs old…. and I am very aware of her situation. However since she was discharged from the Hospital and today will be her first full week on Azodyl… some good days. n some not so good. Her appetite is def getting better…. however her bowel movements are not. I have been giving her the Azodyl in a small amount of wet food…except for a few doses when she would not eat anything… via dilution in water thru an oral syringe. Which we upped to 3x daily …… And I saw improvement right away! She seems a bit constipated now. I think. not sure… And I am looking for ideas on different wet foods I should try. My last kitty lived till 20. never had any of these issues. I just want to keep my Chloe comfortable and alive and happy as long as humanly possible! She is my daughter! If anyone has any ideas or suggestions for a good wet food for her right now . besides my Mobile Vet. ( who I love….and gave me a great dry food… ) please share with me. I thank you all in advance and send all my Strong Jewy Prayers and love to all our furbabies!

  3. P. flanagan says:

    In a pinch when I am trying to stimulate an appetite, avoid too many by products, and get the Azodil into my ancient cats without creating stress, I use one Fancy Feast product. It’s Fish and Shrimp Feast Flaked. It is just fish and shrimp. And it’s a happy medium. My cats stopped vomiting with this combination. Best wishes. I know what you are dealing with. Another product that eliminated vomiting is Royal Canin Baby Cat (not the kitten food, just the Baby cat). Sometimes you just have get a simple, stress free meal into the oldies. And mine will not eat the prescription foods.

  4. v.t. says:

    Dana,

    If your kitty is not producing stool on a regular basis, you need to speak to your vet immediately. She could be having trouble digesting her food, or, the food could be inappropriate for her condition (i.e, not enough moisture, this is only an example) – also some medications can cause constipation, so you need to discuss any medications Chloe is taking, with your vet.

    There are a few things you can do to help Chloe, but only under your vet’s direction – he knows Chloe’s condition better than strangers on the net. He can prescribe medication to help, or recommend a hairball remedy on a temporary basis, or adjusting/changing her diet to one that is more effective – please discuss with your vet promptly.

  5. Michele Burlew says:

    A year ago at this time, I was preparing to put my Homer down. He was diagnosed with KD and seemed to have given up. His BUN & Creatinine were out of whack, his potassium low and he was anemic and miserable. Additionally, KD caused hypertension with rendered him blind and I didn’t even know it until I read up on the disease. I went back to the vet and she prescribed amlodipine for his blood pressure but we were too late to get his sight back (if caught early can sometimes be reversed). To manage his kidney disease I give him Azodyl daily, SubQ fluids daily to every other day and a potassium supplement twice daily to help him stay hydrated. If he has problems with moving his bowels I give him a little lactulose.
    With close management, all of his bloodwork has normalized. He has his usual energy and temperment back. I feed him the KD diet and whatever he’ll eat so I can slip his meds in without bothering him. If your cat is constipated he may needs fluids or just to move around a little more. Good luck!

  6. Gail Thomas says:

    My Ariel is 20 years old. She’s had KD for 4-5 years now. She eats dry K/D & Fancy Feast classic with Azodyl. I recently had to give her IV fluids for about 6 months. The fluids are her last resort. She’s doing better now and not needing the fluids. I stumbled on this article because I just wasn’t sure if the Azodyl was helping her. She’s doing much better now & her creatinine is now only a couple digits higher than they were prior to this episode. I think I’m going to still give her the Azodyl, because I believe that it might be helping her to still be with me for this many years. I hope this helps you.

  7. Lawrence Koepke says:

    My 15 year-old male cat “Delta” was diagnosed with Chronic Kidney Disease (CKD). This was not the first cat in my life with CKD, however, this was the first that received Azodyl. Noting that the manufacturer’s information recommended that Azodyl be given in the capsules to reduce the chances of the stomach acids destroying the bacteria, Delta was given the capsules. Within a week on Azodyl, Delta’s appetite began to return to normal. After a month, his creatinine and BUN values returned to within normal. Delta lived about 18 months after beginning Azodyl, almost all of that time as a normal, healthy cat eating with a regular appetite. It was only after 16 months that the Azodyl began to lose its effectiveness, and the CKD finally overwhelmed the effectiveness of the probiotic mix of bacteria in Azodyl. I am totally sold on Azodyl, as my previous cats simply went downhill and died within a couple of months after being diagnosed with CKD, while Delta returned to normal for well over a year.

  8. skeptvet says:

    Glad things are going well, but of course I’ve seen exactly the same happen in many patients without Azodyl, so it’s not evidence for the product.

    The Problem with Anecdotes

    Anecdotes

  9. Cheryl says:

    This is very expensive and misleading. My son has Ulcerative Colitis and we make our own homemade yogurt which provides the same bacteria needed. It must be fermented for 24 hours to eliminate the lactose, which is not digestible and then rests refrigerated for 8 hours before use. These bacteria do survive a trip through the stomach. I can make 3 quarts of great quality yogurt for less than $12 and it will last two weeks refrigerated. I plan to try adding this to my 14 year old Siamese boy’s food to see if it affects his test numbers. The amount of these bacteria is also way higher than can be contained in capsules, which is why we make it. Store bought yogurt is not made this way and contains lactose.

  10. Heidi says:

    My cat Jezabel apparently has kidney disease (she is 22 years old and looks healthy as a horse, though she seems kind of fragile lately) azodyl has been added to her diet (the vet told me to get it and also said not to give her any food for an hour after) in pill form which is a nightmare lately. I use pill pockets (luckily she doesn’t throw that up) and for a long, LONG time she swallowed it down fine, but now all of a sudden its a fight to get her to take it.

    I put her upside down swaddling style in my arms and have for a while, (She used to just take it from my hand and I would hold her in that way till she swallowed it.

    Now I bring her to the couch, and open her mouth and get it in as carefully as I can, than shut her mouth and squirt a little water in her mouth. But she is growling at me and fighting for all shes worth when before it was pretty easy.

    I can still get her mouth open as I’ve watched videos where you open the sides of her mouth and open from the bottom and that’s worked though she still fights me. But today she was growling and actually panting afterwords…it was terrifying for me to watch as I was worried she was going to stop breathing (she also has breathing issues where she’ll be huffing and puffing)

    Any advice on what to do??

  11. Heidi says:

    Oh and just to comment on my cats health also, kidney problems big time, hyperthyroid problems (Pet Wellbeing thyroid support gold is a godsend for that, otherwise every hour shes begging for food) but she was sleeping a LOT, begging for food a lot, and was VERY lethargic. Not anymore, though I need to try to find a better way to pill her as shes fighting it like hell now, after a year or so of taking a pill popper right out of my hand, I may try giving her the azodyl in liquid form (the powder and a little water) tomorrow in a dropper, maybe that will work better. Then a treat… She doesn’t seem to throw up the pill popper as long as its just one.

  12. skeptvet says:

    Well, since there’s absolutely no reason to think Azodyl will help your cat in any way, my advice is to stop forcing her to take a supplement that isn’t wortwhile. This can only diminish her quality of life and interfere with your bond. The desire to do what you can to help her is understandable, but I think it is leading you to do something counterproductive.

  13. Peter's larger cat says:

    Thank you skeptvet and the commenters for this collection of information.

    My 19-yo tomcat, last month diagnosed with CRF, always loved drinking milk, without any visible bad effects.
    (Either I never understood the lactose problem, or all my cats tolerated milk well).

    I guess, offering my cat some high-quality fresh yoghurt from a bio/eco dairy, instead of industrial one from the discounter, could be a cheaper and more natural alternative to try.

  14. Leslie says:

    I just started my 8yr old flame point Siamese on Azodyl for his KD. He is doing great! He’s been on it for approx 1 month. He’s gaind back some of his weight, eating well, and active. I couldn’t ask for anything more. Azodyl is our miracle so far.

  15. skeptvet says:

    It’s always great to hear of a pet who is doing well, but sadly it doesn’t prove anything about this product. Such stories are told about every failed therapy, from bloodletting to homeopathy, and they just don’t reliably represent the reality. Here’s some more detailed explanation of why:

    Why Anecdotes and Testimonials Aren’t Reliable

  16. Nicole says:

    What do you suggest instead of Azodyl, skeptvet? My 10 yo cat has been on it for a month, plus fish oil and k/d food (hills and royal canin) as much as possible. (I have a second cat who eats regular food. They each prefer the other’s food. So much fun.)

    What it sounds like is that it works for some and not for others. If a pet is ill and Azodyl is the only new thing introduced, and then the pet gets better, how can you say it has had no effect?

  17. skeptvet says:

    I recommend following the International Renal Interest Society (IRIS) guidelines for managing chronic kidney disease. This includes diet change, medications for blood pressure and protein loss as needed, and some other interventions based on the individual case. I don’t recommend Azodyl because there is no reason why it should work and the limited evidence so far suggests it doesn’t work.

    As for why we can’t use anecdotes of apparent successes as evidence that it works for some cats, that’s the core problem with all anecdotal medicine. There is no therapy ever that hasn’t had supporting anecdotes. For thousands of years, people with all kinds of diseases swore they got better after bloodletting, purgatives, toxic heavy metal treatments like mercury, and all kinds of things that not only didn’t work but actually did harm. Our unaided observations are a poor guide to reality when dealing with something as complex as medicine. I’ve written extensively about this, if you are interested, but the bottom line is that anecdotes are a test no treatment ever fails, so either every treatment works or anecdotes can’t be trusted.

    Why Anecdotes Can’t Be Trusted

  18. Janis says:

    Dear Skeptvet..
    Have gone through the IRIS guidelines and cannot find specific diet adjustment advice other than general guidelines…do you have any links to info you respect? There are so many contradicting opinions regarding diet.
    Thanks

  19. skeptvet says:

    You will find some useful information, and also some links to reliable sites, on the page of the World Small Animal Veterinary Association Nutrition Toolkit, under Tools for Pet Owners.

    There’s also some more technical info HERE.

  20. Dr Susanna Hofherr says:

    If anything I find advise sponsored by ‘Hills’ (see WSAVA Nutrition Toolkit no less misleading than Azodyl.
    Why some cats do well on Azodyl is simply because even the limited numbers and variety of beneficial bacteria in this product can make a huge difference in seriously deprived (of beneficial gut-bacteria) animals. For further reading of the immense importance of (a great variety and numbers of gut bacteria) go online and look for new studies. Finally this important topic has been tackled by independent science.
    For a starter good gut flora is the best medicine to prevent depression in humans (no, I am not making this up, see science-based evidence).
    Summary, if your cat is not on natural food that’s free of antibiotic residuals and/or has received antibiotics at any time in her/his life, chances are that giving even limited ‘good gut bacteria’ is better than not giving it. Side note: Azodyl is by no means the best product (in beneficial strains, numbers and preparation).

  21. G says:

    Dr. Hoffher,

    I am interested in reading the research that you used to formulate your educated opinion on this. Please post them. It sounds interesting.

  22. Quin says:

    In the interest of, at least, hedging our bets more affordably with probiotics, I’ll be trying this cheaper human one recommended by a leader of a good cat health community (use 1/4 or less of human dose, sprinkled on food). Also, adding water to wet food is known often help kidney function): [links removed]

  23. Joyce says:

    The one study here that says it doesn’t work does not follow the directions for use on the bottle. Wouldn’t that invalidate the study?

  24. skeptvet says:

    It is a fair question whether or not the change in method could have affected the results. However, that also raises the issue of whether the product can be used in cats even if it is effective, since it is often impossible to administer whole capsules to a cat. Even if the product worked in theory, it wouldn’t be very useful if most cats owners couldn’t use it as directed.

    The other response is that the study in dogs used the product as directed, and it didn’t work for them either. So there is no theoretical reason to believe the product should work and no scientific evidence of any kind that it actually does work. While one cannot prove a negative beyond any doubt, there is good reason to doubt the claims made for this product and, as yet, no reason to believe them.

  25. Miss Kitty says:

    THANK YOU Barbara Brown!!! The cold Butter works much better than Pill Pockets. Great Idea! Very much appreciated.

  26. Michele says:

    I have done a ton of research on KD in cats. The issue with the study mentioned here is that the capsules were opened up, and sprinkled on food which is NOT the suggested administration by the maker; Vetoquinol. It’s not reasonable to expect results if Azodyl is not used as directed. The company specifically advises on the Azodyl bottle that the capsule should NOT be opened up, and should be given an hour before a meal or on an empty stomach. On their site they say it may be given with a small amount of food. Azodyl is in an enteric capsule which allows the Azodyl to get to the lower GI tract. This will not happen if the capsules are opened up.

    I’ve read the study that Vetiquinol conducted on Azodyl, and in fact they themselves have tested Azodyl given on an empty stomach with Azodyl in the enteric capsule, and Azodyl with the capsule opened up for comparison, and they themselves concluded in their study that the opened capsules were not effective.

    It’s important to keep in mind that with any supplement or medication that there’s no one size fits all treatment for animals or humans. What works for one may not work or cause side effects for another. It boils down to trial and error. As we can see in the comments here that Azodyl has helped in some cases.

  27. skeptvet says:

    As I’ve discussed before, the fact that the product was used in a manner different from the instructions does raise questions. However, it also raises the question of how useful the product would be if most owners could not give it according to the instructions because their cats refuse it, which is why it was used in this manner in the study. And just because a negative study is imperfect doesn’t change the fact that there are no published positive studies. Finally, a similar study in dogs did use the product according to the instructions and still found no benefit. So while the limitation in this study you cite is real, it doesn’t somehow mean you can declare the product successful base don anecdotes even in the face of several failures in controlled research studies.

  28. Liha Sayyed says:

    I am trying Azodyl now. My cat sometimes vomits when I give it to him and then he is not interested in eating. If he doesn’t vomit – he is not interested in eating after I give it to him. Are there any other alternatives to this product? Is this product tasteless? Help – I am frustrated and worried.

    Liha

  29. Jennifer C. says:

    Hi. Late to the party here but still hoping for input. I have a 9-year-old cat, Maslow, who was diagnosed with pylonephritis and CKD about a month ago. She had lost some weight and suddenly stopped drinking (which took us immediately to the vet), but otherwise gave us no visible signs of distress. At the time of her evaluation, her BUN was out of the measurable range and her CREA was 9.5. She had not been previously diagnosed with CKD and I thought I was going to lose her pretty quickly. Six weeks later, we still don’t have a prognosis.

    She’s been hospitalized on IV fluids and antibiotics three times since then. During her first hospitalization, she came down from stage 4 to stage 3 or possibly the high end of stage 2 (I don’t have the labs for that stay). A week later her CREA was back up at 7.6 and her BUN was off the charts again. During her last hospitalization, her kidney values actually got worse the first night, and over three days in the hospital, her creatinine only dropped to 7.4 from 8.6. We discharged her when her PCV values dropped to 17% — being on IV fluids was clearly exacerbating her anemia, and after three hospitalizations involving multiple ultrasounds, x-rays, and urine/blood labs (in addition to the visits to/labs at the regular vet and outpatient IV fluid therapy between-times), we just couldn’t afford a transfusion without losing all of our ability to cover the cost of follow-up care. We also can’t afford the battery of tests we’d need to do to see if there’s an ascending infection or other issue that could be causing the ongoing fluctuation in her kidney values and their resistance to IV fluid therapy. So we’re in a tough spot.

    She’s not clinically anemic and is still using the litterbox and eating and drinking on her own, and she just finished a course of two antibiotics to deal with the pylonephritis (her urine culture is negative, but the infection could be persistent). So for now we continue with sub-Q fluids and I do my best to get her to eat a kidney diet. We’ve also been the recipients of some donated darbepoetin, which we’ve just started her on to try to get her PCV values back up above 20%.

    Meanwhile, I’ve been reading my little heart out about CKD and what else we can do to improve her condition and/or her quality of life. I share the skepticism about Azodyl based on this study specifically, and didn’t think it was worth the struggle to pill her at the correct dosage on the off chance that we might see a drop in the waste products accumulating in her blood. However, I did read a study about the administration of Renadyl, which is a similar prebiotic formulated for human consumption. The study abstract is here: http://www.kibowbiotech.com/pdfs/abstract%203.pdf. It showed BUN and CREA improvement across a small group of CRF cats receiving Renadyl over a 60-day period. Improvement was nominal at worst. All owners administered the supplement mixed with food, as none of the cats would tolerate taking the whole capsule orally. (It was speculated that the higher volume of bacteria in the human formulation meant that even when Renadyl is mixed with food, enough bacteria survives to have an impact, but there was no additional research into why the supplement was successful even when administered in food.) Since Maslow’s kidney values are so persistently high, and since 100% of the cats in the study showed long-term, sustainable improvement to their azotemia, it seems like this might be something we want to consider.

    HOWEVER, this was a very small trial conducted at a single veterinary practice in California, and the abstract indicates that the practitioner has a preexisting bias in favor of homeopathic treatments for CKD cats. The research also appears on the site of Renadyl’s manufacturer and is difficult to find elsewhere. That, combined with the lack of corroborating data (and my lack of awareness about whether the study is peer-reviewed) lends itself to a healthy dose of skepticism on my part.

    It’s hard for me to argue with the sustained improvement in kidney values, but I’m still wary of the findings here. I didn’t see in the abstract what kinds of additional medicines or non-homeopathic therapies the cats were receiving (other than a note about the fact that the three subjects that gained weight over the course of the study received additional homotoxicological therapy along with other treatments), or how long their CREA and BUN levels had been stable/increasing before adding Renadyl as a therapy. It’s not clear how it was determined that it was the Renadyl specifically that positively impacted the cats’ azotemia.

    I’ve reached the point with Maslow where reason is starting to give way to emotion and I could use an outside perspective in addition to the “well, it won’t hurt” I got from her regular vet. Can you give me a good skeptic’s gut check on the Renadyl study?

  30. skeptvet says:

    Since there is no reason to think this product will help your cat, and some evidence that it won’t, I would not continue using something that interferes with his appetite or causes vomiting. It is very important for cats with kidney days to eat well if possible. I would talk with your vet about options and take a look at the International Renal Interest Society (IRIS) guidelines for treating kidney disease in cats to make sure you’re doing everything you can.

  31. skeptvet says:

    The paper you link to isn’t really a “study.” It was basically a doctor who believes in alternative therapies trying the product out on some patients and then assuming the improvement in bloodwork was due to the product, as opposed to everything else the owners and the vet were likely doing at the same time. It’s nothing more than an anecdote with no attempt to control for bias, confounding, or any other type of error. None of the features of an actual research study (blinding, randomization, placebo or other control groups, etc) were employed. This is simply haphazard trial and error dressed up to look like science, and it’s no different from all the other unreliable anecdotes and testimonials out there.

    If you search for Dr. Palmquist’s name on this blog, you’ll get an idea of the kind of anti-science perspective he employs. And here’s a review of all the reasons anecdotes like this aren’t reliable.

  32. Jennifer C. says:

    I did search for that particular vet and his emphasis on homeopathic treatments was a red flag for me, as well — as was the lack of pre-screening of the cats taking Renadyl and so much more about the way the “study” was performed.

    It’s been difficult to stay rational when I just want to find something to help Maslow, so I appreciate the voice of reason — and the link to IRIS guidelines. These guidelines are probably the most useful resource I’ve found or been directed to yet. (Now I’m wondering if her creatinine levels went up from 7.9 to 8.4 during the first night of her last hospital stay because she presented with hypertension and they started her on amlodipine.) This is EXACTLY what I needed as we try to understand what’s happening with her kidneys, and as we look to exhaust all of the options that are both within our financial reach and that are most likely to have a positive impact on her health. Thank you.

  33. Karen says:

    Hello all. My 13 y/o flame point himi Junior B., was recently diagnosied with PKD. My vet told me to start him on a Hills renal diet, which is impossible because he has IBD and can only tolerate novel protein. (He has been on Royal Canin Duck and pea for years). After stating I was in between a rock and hard place, she went on to suggest three suppliments. Epakitin, Renal K+ gel, and Azodyl. In researching Epakitin and Renal K+ there is no evidence to support their claims of effectiveness….and now reading the posts here, I’m at a loss as to how to treat him. Anyone with additional thoughts on what can be done to help him feel better would be of great help. With thanks.

  34. skeptvet says:

    I would suggest contacting a board-certified veterinary nutritionist who can formulate a home-cooked diet specifically for your pet’s needs. I have had several patients with kidney disease and food allergies, and this works great!

    You can usually find a nutrition service at the nearest veterinary school, or you can look for a private practice nutritionist here.

  35. Karen says:

    Dear Skepvet,

    Thanks for the info.

    I have been in touch with UC Davis and am hoping to get more guidance info there. Lucky Junior. He’ll be eating better than us soon!

    All our collective best.

    Karen

  36. Irene Rotondo says:

    I’m using Azodyl on my second KD cat, it is effective on my cats. Further more, while it may not be conventional, it has worked for my cats and many other’s

  37. skeptvet says:

    Glad your pets have done well, but it just isn’t the case that this proves anything about this or any other treatment. Here is some more discussion (and a little humor) to illustrate why:

    Why Anecdotes Can’t Be Trusted

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