Feline kidney disease, a.k.a. chronic renal failure (CRF), a.k.a. chronic renal insufficiency… a bit of a daunting topic for me to tackle in a quick lunchtime blog post, I’ll admit. However, I get asked about kidney disease a LOT, so I’m going to give it a stab.
Cause
First, I’ll say upfront I am CONVINCED that dry food leads to the preponderance of kidney disease )(and urinary tract disorders and other ailments) we see today. I could kick myself when I think of the idiocy of treating my first older cat with CRF with sub-q fluids, all the while feeding her a DRY (kibble) diet. Moisture is imperative for good kidney and urinary tract health. While cats fed only dry food drink more water, they do not drink ENOUGH additional water. Studies showed the dry fed cats’ urine was less dilute (contained less water).
Once kidney (renal) function is lost, generally it cannot be regained. So, when I get a call, email, or post asking about a cat with renal insufficiency and whether the cat can be helped, I’m honest. The progress of the failure can be slowed, maybe (optimistically) stopped, but what is lost is GONE and will not return.
Diagnosis
If hyperthyroidism is the most underdiagnosed feline ailment, kidney disease is probably the most overdiagnosed. There are effectively three items we want to look at in diagnosing renal insufficiency:
- Elevated Creatinine (included in a typical chemistry blood panel)
- Low Urine specific gravity (measured with a urine sample in a typical urinalysis)
- Elevated BUN (also included in a typical chemistry blood panel)
I list Creatinine first as I feel it should be given the greatest consideration. However, I would not diagnose kidney disease based on Creatinine alone. Creatinine can be elevated due to dehydration and other issues, not only kidney disease. So, we want to confirm diagnosis using BUN and/or urine specific gravity.
Urine specific gravity tells us how dilute the urine is. A cat fed a wet diet will generally have a lower specific gravity than a cat fed dry food – so we need to keep that in mind when looking at the numbers. Similarly, dehydrated cats will tend to have higher urine specific gravity. Pure water with no sediment has a specific gravity of 1.000. We expect there to be some sediment flushed out by the kidneys in the urine. My cats’ urine specific gravity has ranged from around 1.025 (pronounced ten-twenty-five) to 1.080 (ten-eighty), with the majority around 1.040 to 1.050. (Again, keep in mind If a vet visit showed a Creatinine above the lab’s reference range and a urine specific gravity under 1.030, I’d be suspicious. Depending on how MUCH the Creatinine is elevated and the specific gravity deflated, I’d retest or consider treatment. (If the values are just slightly above the reference range, I’d wait and retest. Values fluctuate – keep in mind tests are just a snapshot in time.)
BUN is where I see the most common cause for confusion and/or misdiagnosis. BUN does not measure a toxin, but a byproduct of protein metabolism. Cats on a higher-protein diet (which, in my opinion, they generally should be) will generally have higher BUN levels than cats on a lower-protein diet. That is NOT a bad thing. An elevated BUN can indicate the kidneys are compromised and not metabolising protein as efficiently as they should – but CRF should NEVER be diagnosed based on an elevated BUN level alone.
Symptoms seen by caregivers generally include excessive thirst and urination.
Dietary Treatment
All cats, and especially cats with renal insufficiency should be fed ONLY wet food! Moisture is imperative in keeping kidneys working properly. Some advocate a low-protein diet for cats with kidney disease – I do NOT. It happens that low-protein diets are generally also low-phosphorus diets, however limiting protein can exacerbate the anemia and muscle wastage commonly secondary to CRF. It can also elevate Creatinine levels. High protein diets do NOT lead to or cause kidney disease, and in my opinion low-protein diets should not be used in treatment of cats with kidney disease. The only exception in my opinion could be very late-stage CRF if BUN is VERY high and an all-wet moderate-protein higher-fat moderate-carbohydrate diet with QUALITY meat protein can be used. I have a huge issue with most prescription “renal” or “kidney” diets as not only are they protein-restricted but the source of what little protein that exists in the food is poor-quality (organ meat, grain glutens, etc.) I’ve watched cats on these diets waste away, and while their decline was blamed on the kidney disease, there’s no doubt in my mind these horrible diets contributed to their demise. I’ve also watched cats diagnosed with CRF, put on low-protein (and high-carbohydrate) prescription diets, only to develop diabetes from the high carbohydrate content of these foods. I fed my last two cats with CRF an all-wet high-protein diet, and neither died of kidney failure, and they looked and acted fantastic until their deaths from heart failure. Afer lived over five years with kidney disease on the same diet I feed all my cats, and her kidney values remained relatively stable all that time.
Once diagnosed, it is important to keep an eye on the cat’s phosphorus levels. The phosphorus levels should ideally remain in the lower half (or better yet, third) of the lab’s reference range. Allowing these values to exceed the range is WAY too high for a cat with compromised kidney function. Always keep in mind lab’s ranges are set for ALL cats, including young, healthy cats. If a good-quality diet with limited-phosphorus can’t be found (and they’re not common, as protein tends to be higher in phosphorus), you can always opt to use phosphorus binders (aluminum hydroxide, Renagel, Epakitin, etc.)
Fluid Treatment
Sub-q (subcutaneous or under-the-skin) fluids may be the cornerstone of CRF treatment. These are relatively easily given at home. (I have a video, below. Poor quality, but it gets across how simple it is.) Sub-q fluids keep the cat comfortable and hydrated and help flush toxins out of the kidneys. I prefer Lactated Ringers (typically used for sub-q fluids) supplemented with injectable B-complex. B-vitamins are water-soluble therefore are depleted by excessive thirst and/or urination, and sub-q fluids. Adding B-vitamins to the sub-q fluids replenish these critical nutrients and may combat anemia.
Medications
Several medications show promise for CRF, including Benazepril and Calcitriol. Benazepril is thought to increase bloodflow to the kidneys. (It’s also used for heart conditions.) Calcitriol is a form of Vitamin D thought to improve their overall feeling of health and well-being.
There’s also a variety of supplements which could be useful, such as omega fatty acids (salmon oil) and CoQ10. (CoQ10 should not be decreased or discontinued if a heart condition is suspected, as it can mask/treat heart ailments.)
Other Conditions
Urinary bacterial infections are rare in most cats, but not cats with kidney disease or other conditions that dilute the urine. Hypertension (high blood pressure) can occur in any older cat, especially a cat with kidney disease. Untreated hypertension can cause blindness, heart attack, or stroke.
Finally
I could expand on this issue for some time, but I think the above covers the basics. For more information, visit the Feline Outreach kidney disease page. As always, if you find this information helpful please consider a donation to this worthy organization!
[…] With the change in diet, we not only saw the episodes of bloody diarrhea Afer occasionally experienced cease (likely a symptom of IBD) – but she gained a bit of weight and increased to around 10 pounds. Though not a lot of weight, her vet commented on how much more “solid” and muscular she felt, rather than frail. I also believe a wet diet is one of the reasons Afer lived over five years with CRF (chronic renal failure, or kidney disease). […]
Some years back, my vet advised me that all canned foods are bad for cats and that I should switch to a premium dry food. She said the phosphorus and fat content of canned foods are too high. I took her advice and now so wish I hadn’t. I have lost three cats to CRF since the switch, where I had seen it in any but my oldest cats previously. I also have two cats, who are only 6.5 years old who have signs of early CRF.
This is a heartbreaking disease, especially in younger cats. I, too, am now convinced that dry food is a major contributor to the disease. My vet now says that there is no definitive evidence of this, but he agrees. So we are transitioning our cats to wet food, supplementing with small amounts of dry. Dry food is convenient and the free-feeding of it can eliminate food aggression in multi-cat households. But it just isn’t worth the risk.
BTW, I believe that treating CRF in cats older than 10 years of age is inappropriate. There is little chance of halting the progression of the disease in older cats and only about a year more of life can be achieved if renal function is below 25%. The treatment becomes increasingly complex and without a background in feline medicine, the owner has little chance of getting everything balanced so that the cat doesn’t suffer. I done this too many times to put an older cat through it. So I recently elected not to treat my 14 year old female, when she was diagnosed. She declined over a six month period and died at home peacefully and with very little suffering.
Hi Lynette,
Thank you for the post and video. I’ve found the video to be helpful as Gump (17.5 yrs) now has some kidney issues and we’ve started fluids every three days or so. Something that I now feel is also a factor in kidney disease is overvaccination. When Gumpy first became diabetic I absorbed so much information about diet and health, but I didn’t get clear about vaccines until a few years ago. It angers me that his “feline-only” vet pumped him with a few vaccines while having a chronic disease (the first problem) and also gave them to a senior cat (most of the vaccinated diseases are diseases of younger cats (not including rabies), and older cats have built up immunity – given that they’ve had kitten vacs). I wonder what those boosters in recent years did to his kidneys (and other organs systems). I also agree that the chronic dehydration from dry food, as well as the urine acidifying additives in dry food are also contributors. I’m also wondering if the stress on kidneys from being diabetic and having high glucose also may play into the weakening of the kidneys for diabetic cats, and possibly even the preservatives found insulin which have to go through the kidneys (I assume). Just some thoughts. I’ve just been pondering this as I’ve been watching my little boy age and deal with weakened kidneys. Yes, age is a factor, but I find it annoying when people post that kidney disease is simply a result of aging. It would be great to read your thoughts on vaccines and the problems with over-vaccination. Dr. Hofve has some good info on her Little Big Cat site about this topic. I hope you and your kitties are doing well. Thanks again for the video.
Hi Jen, thanks for sharing your thoughts!
Best wishes to you and Gump.
Lynette
Lynette, Thank you for all the info on crf, I have an older kitty Isaiah-Ezekiel, who is around 17 and he recently had labs done and the Cr. and BUN were just a tad high, am now waiting for results taken on Friday to see where we stand……….Because of info I got a while ago I have stopped 99% of dry food, I have a diabetic kitty and this has been miraculous for her. I have a total of 16 kitties and took them all off dry food, sometimes I add a pinch of EVO to each but all have lost weight and look great. I try to tell cat friends about the badness of dry and many look at me as if I have 2 heads but I do not quit nagging about it. My cats are all indoor so after initial vaccines when first rescued, I no longer give them and my Vet does not give me a hard time. I lost a kitty to Eosinofil Granuloma at the injection site, he faithfully got all vaccines every year, because of the EG, he spent the last years of his life on Prednisone which destroyed his liver and so no more vaccines for indoor kitties, except when firts brought inside……………Thanks again.Priscilla.
Priscilla, that is great news! Keep nagging! 🙂
Lynette
Hi Lynette, A little update on Isaiah-Ezekiel……..In Jan. BUN was 41…cr was2.5. phos. 4.2……sp. grav.1.018……………….3 mos later, he is……….BUN 46 cr 2.6 phos. 3.4 sp grav 1.017 what do you think? He gets as much wet food as he wants, sometimes a couple of pieces of dry on top, really just a couple and I can certainly stop all of it………………I purchased something called Transfere Factors to add to his food, read that it was good in this case…………….my Vet says there is a new thing called Azodyl that has had real good results, have you heard of it?
Hi Priscilla,
If you have not started sub-q fluids, I would. It wouldn’t hurt to start a probiotic (you can use Azodyl, or I use an over-the-counter probiotic called Natrol Bio-beads) – but I would use sub-q fluids as the biggest defense against further renal deterioration.
Lynette
Wow, Guess I am a little stunned, Had no idea he would need sub-Q fluids already………….Have not read your whole site, what do you use for sub-q and how much and how often? Will also check with my Vet………..Guess I did not realize he was at that stage .thanks for your help.Priscilla
I start fluids early – it’s a great preventative for further deterioration. I generally start with about 100 mL every other day, but talk to your vet.
Lynette
Okay, makes sense, I will look into it right away………Would you believe I am a dialysis nurse, I was wondering if I could sneak him into my office in the middle of the night, just kidding….Will be working on this for him, thanks so much.Priscilla
It is me again, I found a site called Shirley’s Wellness Cafe, you probably know about it already but I found it very helpful…………see what you think…Blessings, Priscilla