By Dr. Becker
Sadly, estimates are that over half of kitty companions 10 years and older suffer from chronic kidney disease (CKD), which is also referred to as chronic renal disease or chronic renal failure. There are many causes of CKD in cats, but one of the most common and preventable influences is a dry food diet.
Kitties are designed to meet most or all of their body’s water requirements through their diet, not at the water bowl, so they don’t have the thirst drive of other species. Kibble provides a very small percentage of the water cats need in their daily diet.
Kitties fed an exclusively dry diet suffer chronic mild dehydration that causes significant stress to the kidneys over time. As Dr. Lisa Pierson, a feline-only practitioner and cat nutrition expert, writes at her fabulous CatInfo.org website, “It is troubling to think about the role that chronic dehydration may play in causing or exacerbating feline kidney disease.”
In addition, the quality of protein in most dry pet food is very poor. It’s rendered, feed-grade protein, which I believe is harder for cats to digest and process. Fed twice a day (or all day) every day for years, it can cause stress to the liver and kidneys.
Why I Don’t Recommend (Most) Prescription Renal Diets for Cats
Once a cat is diagnosed with chronic kidney disease, many veterinarians recommend a prescription “renal diet,” many of which are dry diets (e.g., Hill’s k/d). This has never made sense to me. These formulas do NOT meet the dietary hydration requirements of cats, especially kitties who are losing large amounts of water due to worn out kidneys.
“I must say that I find it truly amazing when I hear about the very large numbers of cats receiving subcutaneous fluids while being maintained on a diet of dry food,” writes Pierson. “This is an extremely illogical and unhealthy practice and every attempt should be made to get these cats on a diet that contains a higher moisture content.”
Prescription renal diets also typically have reduced levels of protein, which is not ideal for cats, who are obligate (strict) carnivores requiring high levels of high quality animal protein for optimal health. According to Pierson:
“Renal diets restrict protein to the point that many cats — those that are not consuming enough of the diet to provide their daily protein calorie needs — will catabolize (use for fuel) their own muscle mass which results in muscle wasting and weight loss.
This internal breakdown of the cat’s own muscle mass will cause an increase in creatinine (and BUN) which needs to be cleared by the kidneys. The rise in creatinine and BUN, and muscle wasting, can lead to an often-erroneous conclusion that the patient’s CKD is worsening.”
Another important consideration is that contrary to what many people continue to believe, studies show aging pets, including those with kidney disease, need more protein, not less.1 But again, it must be very high-quality protein.
Cats fed a low-quality processed diet all their lives often grow addicted to the stuff and refuse to eat anything else. If your CKD cat is hooked on a poor-quality food that is difficult to digest and process, then it may indeed be necessary to reduce the amount of toxic protein in the diet.
However, if your cat is eating human-grade (preferably antibiotic- and hormone-free) protein, then protein restriction prior to late-stage CKD is often counterproductive and can actually exacerbate weight loss and muscle wasting — two common health issues for cats with failing kidneys.
Ideally, if your cat is eating poor-quality food, the goal is to wean him off it and onto a better-quality diet so that adequate protein intake can be continued. I recommend a human-grade, fresh food diet formulated for kidney disease, either homemade or a prepared diet like Darwin's Intelligent Design.
Darwin’s has created the only excellent-quality, fresh food diet specifically formulated for cats with CKD. It can be fed lightly cooked or raw. Unless your cat absolutely refuses to eat anything else, I don’t recommend feeding prescription dry kidney diets.
The Phosphorus Question
Phosphorus is an important mineral that plays a significant role in feline health. One of the jobs of the kidneys is to balance phosphorus levels in the body by removing the excess. In cats with renal disease this ability is compromised, and in fact, many CKD kitties ultimately develop hyperphosphatemia (abnormally high levels of phosphorus in the bloodstream).
Processed renal diets are formulated with reduced phosphorus levels; however, there are ways to accomplish this with a much healthier, high-quality, fresh food diet. For example, the Darwin’s CKD diet contains the natural phosphorus binder chitosan, plus increased calcium to minimize absorption of phosphorus.
Additional Recommendations for CKD Kitties
Vitamins and minerals can sometimes be beneficial for kitties with CKD. I often add a variety of the B vitamins to a cat’s sub-Q fluids. B vitamins can help with anemia, relieve nausea and improve a cat’s overall feeling of well-being.
Antioxidants, L-carnitine and medium-chain triglycerides (coconut oil) can also be beneficial. Adding a source of blood-building supergreens, such as chlorophyll or chlorella, can help fight a low red cell count. I also recommend adding detoxification support, such as dandelion and SOD (superoxide dismutase), if your kitty will consume it.
Probiotics that contain specific kidney supportive strains such as Lactobacillus acidophilus, casei and plantarum, Streptococcus thermophilus and Bifobacterium longum can also be extremely beneficial. These strains, which support healthy urea metabolism, are available in “kidney-specific” products, as well as OTC probiotics, so read labels carefully.
Feline Renal Support by Standard Process can also be very helpful, as well as phosphorus binders and sodium bicarbonate, if appropriate. Your veterinarian will help you decide if these are indicated based on your cat’s specific situation.
Making your kitty’s environment as stress-free as possible is also extremely important. And most important of all in the prevention or management of kidney disease is vigilant monitoring of organ systems. The goal should be to identify risks and subtle changes long before kidney failure occurs. Many cats live long full lives when kidney disease is identified early and managed proactively.