The kidneys are responsible for many important roles within the body, and if they begin to lose their function it can compromise the overall health and wellbeing of the affected cat. Below, we will discuss the role of the kidneys, and more information about chronic kidney disease in felines; including what it is, how it’s diagnosed, managed, and the prognosis.
What job are the kidneys responsible for?
The kidneys wear many hats when it comes to responsibilities within the body, and they truly are a fascinating and impressive organ system. Below will list the primary functions of the renal system:
- Their main function is to filter out waste products from the bloodstream and excrete them in the form of urine
- Regulates electrolyte balance within the body
- Regulates fluids balance within the body and controls blood pressure
- Regulates the acid/base balance within the body
- Creates a hormone called “erythropoietin” which informs the bone marrow to create red blood cells as needed
What is Chronic Kidney Disease?
Kidney disease refers to a pathological process within the kidneys that creates an ongoing loss of function within affected cats, typically senior cats. The term chronic refers to a disease that is present for a long time. The kidneys have a very large reserve capacity to perform the various functions stated above. In order for cats to display clinical signs of kidney disease, at least 2 thirds of their function must be gone. Unfortunately, this means that once signs of kidney disease are seen, the disease process has likely been going on for some time.
What are the signs of Chronic Kidney Disease?
Some early signs of kidney disease may be similar to, and sometimes mistaken for general aging changes such as poor coat condition, lethargy, and/or weight loss. The result of these changes will likely make the affected cat feel ill and are typically caused by a buildup of waste products in the bloodstream that are filtered out by healthy kidneys. In order for the body to cope with this disease process, the kidneys will filter out a smaller portion of these waste products over a greater volume of fluid. Due to the greater volume of fluid that is being processed through the kidneys, this often means that an affected cat will drink more water to compensate for higher fluid loss and urinate more frequently which is another symptom frequently exhibited in early and later stages. In more advanced kidney disease, vomiting, ulcers in the mouth and severe dehydration may be seen.
What causes Chronic Kidney Disease?
There can be many factors involved when it comes to kidney disease and it can be caused by a multitude of other disease processes – below we will list some common examples:
- Neoplasia: Tumors present within the kidneys
- Genetic defects that prevent absorption of specific substances
- Pyelonephritis: This term refers to a bacterial infection within the kidneys
- Viral Infections: This may include a persistent infection of either Feline Leukemia Virus (FeLV) or Feline Infectious Peritonitis (FIP)
- Kidney or ureter stone formation
- Toxin Ingestion: Common examples include antifreeze (Ethylene Glycol) and multiple types of Lily plants
How is Chronic Kidney Disease diagnosed?
Kidney disease is typically diagnosed using a few different testing methods.
- Bloodwork: To test for kidney disease, a blood sample will be drawn from the affected cat. The 2 most common values that will be elevated on a blood biochemistry test in a cat with chronic kidney disease is the BUN (Blood Urea Nitrogen) and creatinine. Both of these products are typically filtered out by the kidneys, and when we see them in high levels in the bloodstream, this indicates the kidneys are not doing their job properly. Other values within this blood panel, such as electrolyte levels, will also help indicate the severity of disease.
- There is also a more recent blood test that has been developed, called an SDMA test, that helps to identify kidney disease before clinical signs are displayed – this test can detect disease earlier at 40% loss of function rather than at 70% loss of function when clinical signs are usually first noticed. This blood test is a great screening tool for detecting early stages of kidney disease so that it can be managed more appropriately before it progresses.
- Urinalysis: Evaluating the urine of the affected cat is also a great diagnostic tool. There are a few important factors that help assess kidney function within the urine. The first is the specific gravity – this factor helps to indicate if the kidneys are still able to concentrate the urine (which is a very important role of the kidneys!). Another important factor to evaluate is whether there is the presence of protein in the urine. In a healthy cat there should be little to no protein present within the urine; if there is, it may be an indicating factor of renal disease. A urinalysis will also help to identify if there are any red blood cells, bacteria, crystals or casts present in the urine which will assist in supporting a proper diagnosis.
Sometimes if the above tests are inconclusive or further evaluation is required for full diagnosis, an abdominal ultrasound may be recommended.
How is Chronic Kidney Disease treated and monitored?
The treatment of chronic kidney disease depends on the cause of the disease, stage, and each individual case. Although some of the most important factors will be listed below:
- Diet change: The most important factor is typically a diet change. Diets formulated for cats with kidney disease will have a decreased protein, sodium and phosphorus content to help lower the amount of waste products that accumulate in the blood.
- Blood pressure lowering medications: A lot of cats with chronic kidney disease will often have high blood pressure (which would be diagnosed prior to beginning treatment). High blood pressure can cause further damage and strain to the kidneys.
- Treatment for anemia if required – As discussed earlier, the kidneys are responsible for creating a special hormone called erythropoietin that is important in red blood cell production. Drugs that stimulate the bone marrow’s production of red blood cells can be used if the affected cat is anemic.
- Antiemetic’s: This category of medication will help decrease and control vomiting if present
- Vitamins B and C: These are both water soluble vitamins and are usually lost in great quantities in a cat with kidney disease due to increased fluid intake and excretion. Supplementation may be necessary.
- Angiotensin converting enzyme inhibitors: This class of medication will minimize protein loss in the urine if present
There are multiple other pertinent treatment options available for cats with chronic kidney disease, although every case will be discussed, diagnosed and managed appropriately on a case by case basis with your veterinarian. There are a multitude of different reasons cats may develop this disease and it is important to treat each cat as an individual to create the most effective treatment plan according to their specific needs and requirements.
What is the prognosis of Chronic Kidney Disease?
When this disease is managed properly, cats suffering from chronic kidney disease can thrive for multiple years following diagnosis, although some felines respond to treatment better than others. The stage of kidney disease once diagnosed and the time frame in which treatment has been started will also be a variable factor on prognosis and longevity for the affected cat. Please seek advice from your veterinarian for more advice on this topic.
Is Chronic Kidney Disease reversible?
Unfortunately, once disease has developed it is unlikely it will be reversed. The best action plan is usually to slow the progression of disease with proper treatment while keeping your cats wellbeing, comfort, and health the top priority. If managed properly, the disease process can be significantly slowed down to allow your cat to live a happier and longer life.
If you have any additional questions or concerns that you would like addressed regarding this topic, please feel welcome to give us a call anytime at 519-893-8937, or book an appointment with one of our lovely fear free certified veterinarians. We would love to speak to anyone who has any further questions or concerns regarding their feline friends!