Kidney disease in cats

Content by Dr Nicole Olewinski – BVSc MRCVS

Kidney disease has many causes, but as kidney function declines, cats tend to develop similar symptoms. The kidneys are a sophisticated filtering system carefully balancing the levels of various substances in the blood and eliminating waste. They do a few other things too, like making hormones to regulate blood pressure and red blood cell production. 

Though many diseases can affect the kidneys, including congenital ones, the end result is the same: progressive damage that forces the remaining areas of a functional kidney to work harder and harder. Sadly, by the time a cat shows symptoms, significant irreversible kidney damage has often already occurred. 

• Chronic kidney disease (CKD) is very common in older cats
• Kidney disease isn’t curable, but it can be manageable
• Typical signs are drinking more, weeing more, eating less and losing weight  
• Acute renal injury is a sudden, severe and very serious form of kidney disease

Although there are some specific issues that affect the kidneys, sometimes there isn’t a single trigger or cause for kidney disease.

The kidneys are delicate and anything that disrupts blood pressure or blood flow can cause damage. Over time, little injuries or scarring can build up, and as the remaining areas work harder, they become even more sensitive to injury. It’s a vicious cycle, and as cats age, changes in kidney structure and function become increasingly common.

Apart from general wear and tear, there are several conditions that can damage the kidneys:

• Congenital and hereditary causes such as polycystic kidneys, amyloidosis, underdeveloped or missing kidneys
• Viral or bacterial infections that target the kidneys or travel up into the kidneys from the bladder
• Toxins like antifreeze typically cause acute renal injury, which can leave lasting damage if the cat is able to recover
• Diseases that disrupt blood flow to the kidneys such as heart disease, blood clots or severe prolonged dehydration
• Cancer affecting the kidney or elsewhere in the body 
• Obstructions to the flow of urine, for example kidney stones or urethral blockage in male cats

Some medications can cause changes in blood flow through the kidneys, which – in a dehydrated cat or a cat that already has some kidney damage – can contribute to kidney injury or disease.

Kidney disease is common in all old cats regardless of breed. However, certain breeds are prone to conditions which can cause kidney disease to develop at a younger age. Persians and related breeds can inherit polycystic kidney disease (PKD), while Abyssinians and some related breeds have a higher risk of renal amyloidosis.

Though the classic signs of kidney disease are drinking more and producing more urine, this goes hand in hand with other symptoms which might include:

• Loss of appetite
• Weight loss, including muscle loss
• Vomiting
• Lethargy, grooming less and sleeping more
• Pale gums, a sign of anaemia
• Constipation
• Smelly breath, dribbling and a sore mouth 
• Weakness or wobbliness

Diagnosing kidney disease is fairly straightforward, as parameters like urea and creatinine are included in many blood screening profiles. However, to try to determine how advanced the kidney disease is, vets often perform additional tests that include:

• Electrolytes, phosphorus and calcium
• Symmetric dimethylarginine (SDMA)
• Blood pressure monitoring
• Urine tests such as specific gravity and protein creatinine ratio 
• Haematology to check for anaemia

If your cat is suspected to have a specific cause or trigger for their kidney disease, advanced imaging, genetic testing or even a kidney biopsy may be needed if a specific diagnosis would change treatment. 

It’s worth considering routine blood tests in older cats to catch renal disease early. While creatinine can vary between cats, it’s usually fairly stable within an individual cat. An upward trend, even if it’s still normal, can be an early warning sign.

For the majority of cats with chronic kidney disease, treatment will include some or all of the following depending on severity:

• Fluid therapy: encouraging more drinking, giving fluids under the skin or, when appropriate, IV fluids
• Renal diets or renal supplements
• Phosphate binders  
• Blood pressure management
• Medication to support red blood cell production
• Anti-nausea or appetite-boosting medications
• Treatment for specific underlying causes

Kidneys are essential and chronic kidney disease is progressive, meaning – sadly, at some point – owners will need to discuss euthanasia with their vets.

Because kidney disease has different stages of severity and is typically a disease of older cats, other problems can and do happen which make predicting how long a cat can live with kidney disease difficult. With early diagnosis, some cats live with chronic kidney disease for 2-5 years. 

“To first-time cat owners, a diagnosis of kidney disease can be terrifying. To long-time cat owners, it sometimes just feels like a fact of life. For anyone though, the first few days or weeks can be very stressful. Some cats need to be stabilised in hospital, and testing is needed to find out how advanced the kidney disease is. 

“After this, things can get easier, but there are three things I’d like to highlight. First, try a renal diet, even if you think your cat won’t eat it. The job of the kidneys is to deal with waste, so feeding the right balance of protein, phosphorus and nutrients can make life a bit easier for the kidneys and help preserve the remaining renal function. 

“Secondly, make it easier for your cat to stay hydrated. Maybe that’s switching to wet food, putting more water bowls round the house, buying a cat fountain or trying fluids under the skin at home. 

“Thirdly, do what’s right for you and your cat and don’t feel guilty. For example, kidney problems interfere with appetite, so already picky cats can become more difficult to feed. Independent ‘don’t mess with me’ cats may not tolerate more invasive treatments at home, like fluids under the skin, and cats with multiple health issues can be incredibly complex, near impossible to manage effectively.

“Because chronic kidney disease is progressive and irreversible, the aim is quality of life – minimising symptoms and stress and maximising comfort. You know your cat, and if trying to slow the progress of the disease is making their quality of life worse, say so.”

Dr Nicole Olewinski – BVSc MRCVS

If you’re thinking about buying a Petgevity Lifetime Plus policy, we’ll consider all pre-existing conditions when offering cover for your cat*. 

When you apply for cat insurance, you need to let us know: 

• Which medical conditions they’ve had in the last two years 
• Their health status now

Find out more about Petgevity’s cat insurance for pre-existing conditions.