By Dr. Becker
Sadly, studies show that about half of all pet cats over the age of 10 suffer from chronic kidney disease. Once the condition is full-blown, it is irreversible and can be difficult to manage. Treatment is strictly supportive and typically involves trying to slow the progression of the disease through dietary changes, fluid injections, and other therapies.
In recent years, researchers at Colorado State University have been investigating a novel therapy for its potential to help cats with kidney failure.
Stem-Cell Therapy as a Potential Treatment for Chronic Kidney Disease in Cats
Veterinarians at the James L. Voss Veterinary Teaching Hospital at Colorado State University have been studying stem-cell therapy as a potential treatment option for kitties with chronic kidney disease, and have recently embarked on their fifth clinical trial.
After a pilot study conducted last year, the team concluded that stem-cell therapy did show promise as a treatment option. And according to the researchers, additional studies have shown that stem-cell therapy can reduce inflammation, support regeneration of damaged cells, slow the loss of protein through urine, and improve kidney function.
According to Dr. Jessica Quimby, a veterinarian who is leading the research project:
"In our pilot study last year, in which stem cells were injected intravenously, we found stem-cell therapy to be safe, and we saw evidence of improvement among some of the cats enrolled in the trial. In this [fifth] study, we will further explore stem-cell therapy with the new approach of injecting the cells close to the damaged organs. We hope this proximity could yield even better results."
How the Current Clinical Trial is Being Conducted
Currently CSU researchers are conducting their fifth clinical trial to further evaluate whether stem cells are able to repair damaged kidneys. They are seeking cats with the disease to participate in the study. They are looking specifically for cats local to the CSU area, and kitties with concurrent diseases aren’t eligible.
This fifth trial involves injecting stem cells grown from the fat tissue of young, healthy cats (who are not harmed, according to CSU researchers) into the study cats in the area around the kidney called the retroperitoneal space. The kitties receiving the stem cells are given a mild, fast-acting sedative that is reversed after the procedure.
Diagnostic tests including a complete blood count, blood biochemistry, urinalysis, and urine protein-creatinine ratio will be performed immediately before the injection, two weeks post-injection, and again a month after injection. A test called a glomerular filtration rate will also be performed on each kitty at the beginning and end of the study to evaluate kidney function. This test also requires use of a mild sedative.
Risks associated with the procedure include discomfort at the injection site, and lethargy from the sedation. Even though the stem cells being injected into the study cats are from other cats, there doesn’t appear to be a problem with an immune reaction to the foreign cells.
Researchers monitor participant cats for about two months total, and a variety of diagnostic tests are performed both before and after stem-cell treatment to evaluate kidney function.
Disappointing Results of Previous Studies
In the abstract of the pilot study mentioned above, Dr. Quimby and colleagues note that:
“Despite the possible benefits of intrarenal MSC [mesenchymal stem cell] injections for CKD [chronic kidney disease] cats, the number of sedations and interventions required to implement this approach would likely preclude widespread clinical application. We concluded that MSC could be transferred safely by ultrasound-guided intrarenal injection in cats, but that alternative sources and routes of MSC therapy should be investigated.”1
And in three subsequent studies of therapy delivered intravenously using cryo-preserved stem cells, the researchers concluded that:
“Administration of cryo-preserved aMSCs was associated with significant adverse effects and no discernible clinically relevant improvement in renal functional parameters. Administration of aMSCs cultured from cryo-preserved adipose was not associated with adverse effects, but was also not associated with improvement in renal functional parameters.”2
Given the invasive nature of the stem-cell treatments, the inherent dangers of sedation, and the less-than-promising results of the treatments so far, I can’t in good conscience recommend subjecting sick kitties to clinical trials as described above.
Cats with chronic kidney disease are typically older and may not have much time left. Visits to the vet or animal hospital are stressful for all cats, and especially cats who don’t feel well. While I certainly understand the need to find better treatment options for cats with CKD, putting an already sick kitty through the stress, pain and risk of an unproven experimental procedure isn’t something I would advise.
Causes of Feline Kidney Disease
Chronic kidney disease is primarily a problem of older kitties, though there are causes for the condition in young cats, including malformation of the kidneys at birth, and congenital polycystic disease.
Underlying diseases that can cause kidney failure include high blood pressure, immune system disorders (for example, systemic lupus), exposure to toxins (for example, the 2007 pet food melamine contamination catastrophe), an acute kidney episode that damages the organs and leads to a chronic problem, chronic obstruction of the urinary tract, and certain drugs including NSAIDs and nephrotoxic antibiotics.
Some infectious diseases, including FIV and feline leukemia, can damage kidneys, as can heavy metal exposure, abdominal trauma, and possibly diabetes.
Research conducted by Colorado State University a few years ago points to a link between feline distemper vaccines and immune-mediated inflammation of the kidneys,3 which is a cause of CKD. Panleukopenia (also known as feline distemper) is a life-threatening disease, and kittens should receive their initial vaccine series, since unvaccinated cats may be at risk. But adult cats who were successfully immunized as kittens do not need repeated boosters, and cats with kidney disease should not be vaccinated at all.
Feeding cats an exclusively dry food diet is also associated with development of CKD. Cats are designed by nature to get most or all of their water from their prey, and they don’t have the thirst drive of other species. Kibble provides a very small percentage of the water a canned or raw diet provides. Cats eating only kibble suffer chronic mild dehydration that causes significant stress to the kidneys over time.
Dry diets are also linked to feline lower urinary tract disease (FLUTD), because they result in highly concentrated urine.
Nourishing a Cat with Chronic Kidney Disease
Kidney disease is a leading cause of death in domestic cats, but not in wild cats. In my opinion, feeding high-quality protein in its natural, unadulterated form as soon as a kitten is weaned means that cat will have a moisture-dense diet over a lifetime. This will take an enormous amount of stress off the kidneys.
A diet high in excellent quality protein and lower than normal amounts of sodium and phosphorous is recommended. Controlling phosphorous intake has proven to be very important in slowing the progression of kidney disease.
Many veterinarians still insist that a renal diet should be low in protein, despite studies that show aging pets -- including those with kidney disease -- need more protein, not less. But it has to be very high quality protein.
If your cat is addicted to a poor quality food that is difficult to digest and process, I recommend you reduce the amount of toxic protein in the diet. However, if your cat is eating human-grade protein, then protein restriction is often counterproductive and actually exacerbates problems of weight loss and cachexia (muscle wasting) -- two common health issues for cats with failing kidneys.
Many veterinarians will suggest a prescription dry food diet for kidney disease, but I recommend against this as well. Unless a prescription dry food is the only food your cat will consume, I don’t recommend you feed prescription dry kidney diets.
Cats with renal disease do best eating high-quality, human grade canned food or a fresh, balanced homemade diet. Cats with the disease still eating kibble should be transitioned if at all possible to a diet that provides much more moisture to help nourish the kidneys.
Most importantly, cats with kidney disease must continue to eat. Unlimited access to fresh water should always be provided.
There are a variety of other therapies that can be helpful depending on your kitty’s symptoms. Vitamins and minerals can sometimes be beneficial. I often add a variety of the B-vitamins to a cat’s sub-Q (subcutaneous) fluids. B-vitamins can help with anemia, improve a cat’s overall feeling of well-being, and also help with nausea.
I also use a probiotic specially formulated for kidney support called Azodyl.
Standard Process Feline Renal Support can also be beneficial, as well as phosphorous binders and sodium bicarbonate, if appropriate. Your veterinarian will help you decide if these are indicated or not based on your pet’s specific situation.
Making your cat’s environment as stress-free as possible is also really 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 full and very happy lives when this disease is identified early and managed very proactively.