Chronic Kidney Disease in Cats
What is Chronic Kidney Disease?
Chronic kidney disease (CKD) is one of the most commonly encountered metabolic diseases in dogs and cats. CKD results from the gradual loss (weeks, months to years) of kidney functional units called nephrons. When nephrons are damaged, they are replaced by scar tissue and hence, there are less and less functioning units as the disease progress. Kidney failure occurs when the kidney is no longer able to perform normal functions such as regulating body fluid and removing toxins from the body. Chronic kidney disease is irreversible, however, the progression of the disease can be slowed down with appropriate treatments.
Cats of any age can develop CKD, however, most of the time it is diagnosed in cats older than 9years of age.
There are many potential underlying causes for CKD in cats. Certain breeds are more susceptible to CKD, such as the Maine Coon, Abyssinian, Siamese, Russian Blue and Burmese. Kittens which develop CKD are more likely to have a genetic predisposition, and hence subsequent breeding from the cat is not encouraged. Exposure to certain toxic chemicals, medications or bacterial infections of the urinary tract or kidneys increases the chances of a cat developing CKD. Underlying diseases such as hyperthyroidism or immune mediated disorders can also lead to CKD.
Early detection is the key to manage and slow down the progression of kidney disease. Commonly, the early clinical signs are subtle and vague but not undetectable.
- Increased urination (> 50 ml/kg/day)
- Increased in drinking (> 50-60 ml/kg/day for cat on dry food, > 10ml/kg/day for cat on wet food)
- Inappetance/ anorexia
- Mouth ulcers/ smelly breath
- Vomiting/ diarrhoea
- Tiredness/ less active (lethargy) / weakness (including flexing of neck downwards)
- Weight loss
- Increased respiratory rate
- Late stages: seizures, coma and death is possible
** High blood pressure also occurs in some patients, and could cause damage to other organs such as the heart, eyes and brain, which could result in sudden loss of vision or seizures.
If your vet suspects that your cat has CKD, they will usually recommend running a complete blood test and a urine test for starters. The most common findings suggestive of CKD are elevated blood levels of substances that are normally excreted in the urine – these include blood urea nitrogen (BUN) and creatinine (CRE). The higher than normal levels of these substances in the blood indicate that the kidneys are not adequately filtering these waste products out of the body. The blood test may also reveal low potassium and high phosphate levels.
It is also common for cats with CKD to have a low red blood cell count as the kidney is also responsible for producing red blood cell precursors in health, and damage to the kidneys can result in reduced production of these precursors.
The most common findings associated with CKD in the urine test include minimally concentrated urine indicative of reduced functional capacity of the kidney, as well as protein in the urine.
Your vet may also recommend further imaging of the kidneys and the urinary tract. An abdominal xray may help to rule out underlying conditions such as kidney stones, and may hint at abnormalities of the kidney size or margins. An ultrasound examination may show shrunken kidneys which are much smaller in size than normal, with irregular margins.
Treatment of CKD
Treatment for chronic kidney disease (CKD) in cats aims to reduce the clinical signs, associated illnesses and slow the course of decreasing kidney function.
Dietary therapy is a proven benefit in managing chronic kidney disease. Prescription diets are formulated to provide food with reduced sodium, while also containing increased potassium and magnesium for supplementation. One scientific trial showed that cats fed a "prescription kidney diet" lived an average of 633 days after diagnosis, in comparison to cats fed normal diets who lived an average of 264 days.
Treatment to aid hydration of the cat, and therefore it's kidneys, are crucial. Increasing water intake can be accomplished by providing appropriate numbers and types of water bowls such as low wide dishes and water fountains. Flavoring their water for example, with soup stock or tuna water, can also help. In more critical cases, the cat may need daily or weekly fluid therapy via subcutaneous (under the skin) or intravenous (drip/into the vein) fluid therapy.
Other associated illnesses and effects of chronic kidney disease in the body include urinary tract infections, high blood pressure, and high levels of phosphate in the blood. Later stage effects seen also include anaemia and excessive protein loss (leading to hardening of the kidneys) forced through the kidneys. All the afore-mentioned can be tested for by your veterinarian and be treated with specific therapies.
Chronic kidney disease in cats is unfortunately not a curable disease. Nevertheless, cats can be supported well if good management is started early, close owner observation of their condition by is kept and appropriate tests are conducted to determine the right therapy plan. For example, your veterinarian may suggest to routinely test their urine and blood.
For more information about managing chronic kidney disease in cats, or if you suspect your cat may be showing any signs of kidney disease, please contact your veterinarian.
Informations are provided by
Dr. Geetha Swaminathan
Dr. Jessica Wong
Dr. Julia Tang