- Kidney disease in cats happens when one or both kidneys stop working correctly.
- There are two types of cat kidney disease—acute (sudden) and chronic.
- Cats usually don't show symptoms until the disease has progressed.
- Symptoms include increased drinking and urination, weight loss, poor coat quality, and vomiting.
- Treatment may include a prescription diet, medical management, IV fluids, or a combination of treatments.
Have you taken your cat in for a check up lately? While your cat may appear happy and healthy on the outside, that may not be the case internally.
Checking for signs of kidney disease in cats is one of the most important reasons that pet parents should take their felines in for routine veterinary exams and lab testing. Kidney disease is very common in cats and is all too often diagnosed late in the course of disease, when the prognosis is worse.
This article will explain what cat kidney disease is, how it is diagnosed and treated, as well as common symptoms to look out for.
What is Feline Kidney Disease?
The kidneys are a pair of organs that serve very important roles both in our cats’ bodies. The kidneys are responsible for the following functions:
- Maintaining normal hydration
- Maintaining normal blood pressure
- Getting rid of toxins and waste products from the blood
- Maintaining normal electrolyte balance
- Maintaining normal blood pH (proper balance of acids and bases)
- Producing certain hormones
When the kidneys lose their function, it can wreak havoc on your cat’s body and make her very sick.
Kidney disease is much more common in older cats. Studies estimate that 1 to 3 percent of the overall cat population has kidney disease . While kidney disease was found to affect up to 40% of cats over 10 years of age and 80% of cats over 15 years of age .
Types of Kidney Disease in Cats
Kidney disease is divided into two main categories—acute and chronic.
Acute kidney disease, also called acute kidney injury (AKI) or acute kidney failure, comes on very suddenly, will usually make a cat very ill, and requires hospitalization. Acute kidney disease is commonly caused by toxins, such as antifreeze ingestion, certain infections, and urinary blockages. If treated rapidly, AKI may be reversible, however, it will make a cat more prone to developing chronic kidney disease down the road.
Chronic kidney disease (CKD)—also called chronic renal failure—is much more common than acute kidney disease and is diagnosed when kidney abnormalities (whether found on lab tests or imaging) are present for 3 months or longer.
The remainder of this article will focus on chronic kidney disease.
Stages of Kidney Disease in Cats
Most veterinarians use the International Renal Interest Society (IRIS) staging system for chronic kidney disease . Chronic kidney disease is a progressive disease and is divided into four stages of increasing severity, based on blood creatinine and blood SDMA concentrations.
Stage I: Cats are rarely diagnosed this early in the course of kidney disease. Persian cats that test positive for the polycystic kidney disease genetic mutation without any laboratory abnormalities would fall into this category. Abnormal kidney structure may also be found incidentally during an abdominal ultrasound that would indicate stage I. No abnormal symptoms are present at this stage. No treatments are recommended at this stage but careful monitoring of blood and urine tests is recommended to monitor for progression into stage II.
Stage II: At this stage of kidney disease in cats there will be mild changes to blood and urine values. Symptoms may or may not be obvious to pet parents and include an increase in water intake and frequent urination. It is recommended to start your cat on a prescription kidney diet at this stage.
Stage III: Significant disease is present at this stage of feline kidney disease, and symptoms are usually present. These may include increased water intake, increased urination, decreased appetite, weight loss, vomiting, and poor coat quality. In addition to feeding a prescription diet, certain medications and supplements may be prescribed.
Stage IV: Also called “end-stage” kidney disease. Cats in stage IV of chronic kidney disease have a poor prognosis and often need to be hospitalized to receive intravenous fluids.
Causes of Cat Kidney Disease
In most cases, cats with kidney disease have idiopathic disease, meaning the cause is unknown. However, some things known to cause kidney disease in cats include:
Certain toxins or drugs. Toxins (i.e. ingestion of lilies, antifreeze, and ibuprofen) cause acute kidney injury which may lead to chronic kidney disease
Trauma. This causes decreased blood flow to the kidneys and starves the kidneys of oxygen.
Bacterial infections. These can lead to long term damage to the kidneys if not treated promptly.
Kidney stones. Stones block normal passage of urine through the urinary tract causing excess pressure, which damages the kidney that is blocked.
Polycystic kidney disease. This is a condition characterized by abnormal fluid-filled cysts throughout the kidneys.
Cancer. Certain cancers including lymphoma and leukemia can infiltrate the kidneys and damage their structure.
Certain autoimmune conditions. These will cause abnormal immune complex molecules to form within the kidneys, leading to damage.
Diagnosing Feline Kidney Disease
Your veterinarian will diagnose chronic kidney disease primarily based on blood and urine testing. Consistently elevated blood creatinine and/or SDMA levels together with a low urine concentration support a chronic kidney disease diagnosis. SDMA stands for symmetric dimethylarginine, which is an amino acid that is produced when protein is broken down and excreted through the kidneys.
The veterinarian will also use symptoms provided by the pet parent and exam findings to support the diagnosis.
An abdominal ultrasound is also very helpful in diagnosing kidney disease in cats, as it provides a detailed image of the kidneys and helps to check for underlying conditions, such as kidney stones and polycystic kidney disease.
Once chronic kidney disease is diagnosed, blood pressure and urine protein to creatinine ratio testing is important and will determine the need for certain medications. Cats with chronic kidney disease are also more prone to developing urinary tract infections (UTIs) so urine cultures may be indicated from time to time.
Life Expectancy For Cats With Kidney Disease
It is impossible to predict how long a cat can live once diagnosed with chronic kidney disease, as every cat will progress at different rates.
However, cats diagnosed in stages I and II that are appropriately managed may live several years. Meanwhile, a cat diagnosed in stage IV would likely succumb to disease within weeks to months.
Treating Kidney Disease in Cats
There is not a direct treatment for kidney disease in cats. Once a portion of the kidney’s function is lost it cannot be regained. However, appropriate management of the disease can stop or slow the progression of the disease.
The mainstay of treatment for chronic kidney disease is to feed them a prescription renal (kidney) diet. Cats who eat prescription renal diets may live twice as long as those that do not . These diets are low in phosphorus, moderately protein restricted, contain omega 3 fatty acids and other compounds that are beneficial to the kidneys.
Cats should be transitioned to a prescription diet as soon as they are in stage II or higher. Switching to the diet early on, before the cat has lost its appetite, will result in better acceptance of the food. Transitioning the food very gradually over a few weeks to months is recommended, especially for picky eaters.
If possible, a wet or canned diet is preferred over the dry version, as cats with chronic kidney disease are prone to dehydration. Pet parents should also ensure plenty of access to fresh water by placing multiple bowls throughout the house or using pet drinking fountains.
Medications for Cat Kidney Disease
Depending on your cat’s lab test results or symptoms, she may need the following medications or supplements to help manage chronic kidney disease:
- Blood pressure medication: amlodipine, telmisartan
- Ace inhibitors: benazepril
- Phosphate binder
- Potassium supplement
- Appetite stimulant: mirtazapine
- Anti-nausea medication: maropitant
Cats in stages III and IV may also benefit from receiving subcutaneous fluids—fluids administered under the skin—to treat dehydration. Pet parents can be taught to perform this at home to reduce costs and stress on the kitty.
General Cost To Treat Kidney Disease In Cats
When chronic kidney disease is first suspected, you will need to bring your cat to your vet more frequently—usually monthly—to have her examined and complete lab testing.
After the first few months, if the disease is stable, exams and lab work should be performed every 3 to 6 months.
Cost to treat kidney disease in cats will vary depending on your location but estimates are as follows:
- Exam: $40-$80
- Blood and urine tests: $100-$400
- Abdominal ultrasound: $300-$500
- Medications (if necessary): $20-$60 per month
- Prescription food: $40-$80 per month
How To Prevent Kidney Disease In Cats
Since the cause of kidney disease in most cats is still unknown, there aren’t many things that pet parents can do to prevent it. However, certain risk factors do exist. Periodontal disease is a known risk factor for chronic kidney disease in cats as well as humans. Daily home dental care and annual dental cleanings can prevent and minimize periodontal disease.
Cats should be kept away from known toxins and drugs that are harmful to the kidneys. All kittens should be vaccinated against FeLV and vaccination should be continued for adults that spend unsupervised time outdoors. Some veterinarians recommend feeding cats all or mostly wet food to prevent kidney disease but research is still needed to see if this would truly help.
Remember that early detection of chronic kidney disease is key to a good outcome. Taking your cat to the vet regularly is crucial. Cats over the age of 7 should ideally be examined every 6 months and receive blood and urine testing at least annually .
- Polycystic kidney disease
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