Feline Chronic Kidney Disease
If you have an older cat, you may have heard your veterinarian mention kidney function as an important part of measuring health. Your cat may even have been recently diagnosed with kidney disease. Chronic kidney disease, or CKD, is very common in cats, as up to a third of cats over fifteen years old are affected. As our pets are living longer lives, diagnosis and management CKD has become even more important.
What exactly is Feline CDK?
So what exactly is chronic kidney disease? The term refers to progressive, irreversible loss of kidney function. Although it cannot be cured, progress can potentially be slowed, and symptoms can be controlled in order to maintain quality of life as long as possible. The disease can be caused by several underlying processes, including chronic inflammation, infection, cancer, kidney stones, toxins, infectious diseases, or congenital abnormalities.
In order to understand what CKD does, it is necessary to understand the function of healthy kidneys. The kidneys are two bean shaped organs in the abdomen. Their main task is to filter blood and produce urine. This involves filtering out and removing metabolic wastes, especially those produced by protein breakdown.
Kidneys perform a variety of essential tasks in the body,
The kidneys are vital in controlling fluid balance and maintaining hydration. During blood filtration and urine production, they need to concentrate the urine, or a large amount of water would be lost to eliminate waste. Additionally, the kidneys regulate the levels of several electrolytes. They are also responsible for producing several hormones, including one which stimulates the production of red blood cells.
In other words, they are consummate multi-taskers!
When kidney function is reduced, a variety of clinical signs may be noted. Oftentimes, the first sign is increased thirst and urination, as more water is being lost in urine.
Many cats also develop vomiting and a decreased appetite. They may have decreased energy, drooling, or even oral ulcers. Weight loss, especially including loss of muscle mass, is another common sign. However, it is important to note that many cats in early kidney failure are asymptomatic!
One of the first signs of CDK is increased thirst.
However, these early stages are when intervention is most likely to slow progression of disease. This is one reason why regular screening labwork for geriatric cats is so crucial.
This naturally leads to the question: how is kidney failure diagnosed? The mainstay of diagnosis is a urinalysis and certain types of bloodwork.
Capturing a urine sample can be a challenge. Ask our staff for some “tricks of the trade” like NoSORB to help make collection easier.
The urinalysis will typically show a decreased ability to concentrate urine. A serum chemistry (a routine type of bloodwork) may reveal increased blood urea nitrogen (BUN) and creatinine. These are metabolic byproducts that the kidneys should remove. Increased BUN and creatinine are largely responsible for why cats in kidney failure feel sick. Elevated levels of these compounds cause a condition known as uremia, and are responsible for the nausea and vomiting these patients experience. Other changes on bloodwork may include electrolyte imbalances, such as decreased potassium and increased phosphorus. Many cats in kidney failure are also anemic, meaning that they have low levels of red blood cells.
Another common screening test for kidney function in cats is symmetric dimethylarginine levels, or SDMA. In some cats, this may be a more sensitive and early marker of loss of renal function.
Once kidney failure is diagnosed, additional tests are often recommended in order to best guide treatment. Many cats with kidney dysfunction have concurrent urinary tract infections, so a urine culture and susceptibility may be performed. This test grows out bacteria that are present in urine and determines which antibiotic would be best suited to treat the infection. Another common urine test is a urine protein: creatinine ratio. This determines if your pet is losing a significant amount of protein in their urine. In cats with CKD, protein in the urine is associated with a shorter survival time, and medical therapy can help ameliorate this problem.
While in the clinic, your veterinarian may also take your cat’s blood pressure. Cats with CKD are prone to hypertension, which can lead to problems in the brain, eyes, heart, and kidneys. Uncontrolled hypertension can lead to blindness, brain damage, and further loss of kidney function. Therefore, early identification is vital. Your vet may also recommend abdominal imaging, such as radiographs and/or ultrasound. This allows assessment for kidney stones, renal masses, and other underlying causes of kidney failure.
After diagnosis, treatment for kidney failure depends on the severity of signs and lab abnormalities in a particular pet. One of the first goals of treatment is rehydration.
In an acutely decompensated cat with significantly increased BUN and creatinine, hospitalization is typically required for several days of intravenous fluid therapy. This allows full rehydration, and will drive down levels of uremic toxins. For long term management, it is important to encourage your cat’s fluid intake. This can mean switching to canned foods or adding flavorings (such as tuna juice) to their water.
Oftentimes, regular administration of subcutaneous fluids (fluids given under the skin) are part of a long term treatment plan. This often occurs every day or several times a week. At ACMP, we are happy to see your cat for subcutaneous fluids, or to teach you to administer fluids yourself if you are comfortable with it.
Fluids administered under the skin can be part of a long term treatment plan.
Nutritional management is also a large part of treatment. Most cats with renal disease will benefit from being fed a kidney specific diet.
Typically, this is a specially designed prescription diet low in phosphorus, sodium, and protein. The exact diet may depend on your pet’s stage of disease. Especially early on in the disease course, a renal diet may slow progression of disease.
Additional medications may also be indicated for certain cats. These may include medications to decrease nausea and stimulate appetite, decrease blood pressure, or decrease loss of protein in the urine. Supplements to increase potassium or decrease phosphorus may also be prescribed. For some cats with severe anemia, your vet may suggest injections to stimulate production of more red blood cells.
During treatment, you will need to work closely with your veterinarian. This oftentimes means a vet visit at least every few months.
Bloodwork may be repeated in order to monitor progression of disease or electrolyte levels.
If your cat is currently being treated for CKD, you may be wondering what their prognosis is. This depends on their stage of disease, typically measured by severity of lab abnormalities at diagnosis. Hypertension, increased phosphorus, anemia, and protein in the urine are all associated with a poorer prognosis. However, many cats with kidney disease can live years if properly managed. Even newly diagnosed cats with late stage disease can often be managed for several months.
At ACMP, we can help tailor a treatment plan to your specific cat’s needs and issues, as well as your lifestyle and abilities. Working together, we can help increase the amount of quality time you have with your cat.
Little, S. (2016). Evidence-Based Management of Chronic Kidney Disease in Cats. AAFP 2016. https://www.vin.com/doc/?id=8292264.
Rothrock, K. (2016, April 18). Chronic Kidney Disease. Retrieved August 9, 2018, from https://www.vin.com/Members/Associate/Associate.plx?DiseaseId=1087.
Scherk, M. (2016). Feline Chronic Kidney Diseases in 2016: What’s New? Wild West Veterinary Conference 2016. https://www.vin.com/doc/?id=8282497.