What do the kidneys do?
The kidneys do many important jobs. They filter waste products from the blood into the urine so that they can be removed from the body. They also control the levels of some important minerals (sodium and potassium), regulating the cat’s water and salt balance. They also help to manage blood pressure and control the numbers of red blood cells produced by the bone marrow. Hence you can see that they are very important little organs!
What is chronic kidney disease in cats?
Chronic kidney disease (CKD) is the most common type of kidney disease in cats and it is where they slowly stop working over time. The kidneys have a large reserve capacity, so cats can lose 60-70% of functional kidney tissue before signs of CKD may develop (hence you can donate one of your kidneys). In most cases CKD is thought to be caused by old age, but other causes include infections, toxins (e.g. lillies), stone formation, tumours, and underlying genetic conditions. The high protein diet that cats eat as obligate carnivores is also thought to have a damaging effect on the kidneys over time, as they must work hard to remove the breakdown products.
What are the signs of CKD in cats?
The signs of CKD are often initially subtle and vague, gradually becoming more obvious as time goes on and the kidney disease worsens. Typical signs include:
- Increases in thirst and urination
- Weight loss
- Poor coat quality
- Reduced or loss of appetite
- Muscle weakness (sometimes seen as low head carriage – due to low potassium)
- Vomiting (if toxins are building up)
- Bad breath (can smell metallic due to a build-up of urea)
- Mouth ulcers
- Sudden blindness
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When should I contact my vet?
If you notice any of the symptoms above then please speak to a vet. The earlier CKD is diagnosed, the greater the chance of being able to slow further damage and therefore prolong your cat’s life.
How is CKD in cats diagnosed?
Kidney disease is diagnosed using blood and urine tests. The vet looks at the urine concentration to see if it is more dilute than it should be. They also look at whether there are substances present in the urine that shouldn’t be there, such as protein and blood. The vet also looks at the concentration of waste products in the blood to see if they are higher than they should be, which may indicate that the kidneys are not getting rid of them as effectively as they should. Other investigation may also be suggested, including blood pressure measurement, retinal (eye) examination, ultrasound and radiographs (x-rays).
What is the treatment for chronic kidney disease in cats?
While there is no cure for CKD, treatment can slow the progression of the disease and is aimed at supporting kidney function and minimising the complications from CKD. Dietary management is key in this regard. It is important that the cat is regularly checked by a vet to monitor blood and urine tests, as well as blood pressure. Management of CKD typically involves the following:
- Dietary management
- Maintaining fluid intake is key, given that cats with CKD are prone to becoming dehydrated. They should therefore be fed wet food where possible.
- Protein restriction is important, as many of the toxic compounds that accumulate in the blood in CKD are from the breakdown of protein. By reducing the amount of protein in the diet we can help to reduce this accumulation. It is important that this restriction is done very carefully though, and we recommend feeding a recognised renal diet such as the ones available in our shop.
- Restricting the amount of phosphate in the diet has been shown to prolong the life of cats with CKD. If blood phosphate levels remain high despite dietary restriction then phosphate binders can be added to the diet – these reduce the amount of phosphate absorbed from the intestine into the blood. We stock one of these products in our shop called Pronefra.
- Some cats can be fussy and changing diets can therefore be hard. Do not make any sudden changes, gradually increasing the amount of the new diet over the course of at least several days, if not a few weeks for very fussy cats. Warming the food gently to around 30˚C can help to increase the palatability.
- Encouraging water intake
- This can be achieved by feeding a wet rather than dry diet or adding water to the biscuits if your cat will simply not eat wet food. You could also try using a water fountain, as some cats like to drink from a moving stream of water (hence some like to drink from the tap!). We have these available in our shop.
- Sometimes potassium may need to be added to the diet as blood levels can be low, leading to muscle weakness. This is available to purchase from our shop.
- If the blood pressure is high then medication can be prescribed to reduce this.
- If there is protein loss through the kidneys then medication can be used to help reduce this loss, which can be damaging to the kidneys.
- If the cat is quite severely anaemic then a medication is sometimes used to increase red blood cell production in the bone marrow.
Can cats recover from chronic kidney disease?
The outlook for cats with CKD can be quite variable, with some cats living for many years after their diagnosis while others deteriorate far more quickly. Some research suggests that protein loss through the kidneys into the urine is associated with a less favourable outlook. It also appears that the earlier the CKD is diagnosed and therefore managed, the better the outcomes with regards to survival time and quality of life.