Chronic kidney failure is a relatively common problem in both cats and dogs. Although kidney failure can occur in young animals, it is more commonly seen in the older pet.
If your pet has kidney problems, one of the ways you can help it is by feeding a diet which is specially formulated for your pet’s condition.
Understanding Kidney Function
The kidney is a vital organ in any mammal, involved in keeping everything flowing essentially:
- Waste product removal
The digestion of food results in the production of waste products. Blood containing these waste products, as well as water and minerals (e.g. phosphorus), is taken to the kidney to be removed in the urine. Two important nutrients to consider are protein and phosphorus.
The proteins that your pet eats as part of their diet are broken down into smaller units called amino acids which are used by the body for growth, the replacement of old cells, and the regulation of body functions.
There are 20 different amino acids which can be re-assembled by the body, for example, into hormones, muscle tissue and cell wall components. The amino acids that are not needed are converted into urea to be removed in the pet’s urine, by the kidney
An important role of the kidney is to moderate the level of phosphorus in the blood. In the kidney, the blood is transported down a series of tubules (nephrons) where some of the water and any useful nutrients are reabsorbed from the tubules back into the bloodstream.
The urine that is formed is then stored in the bladder until the dog or cat urinates when it flows to the outside through a tube called the urethra
- Regulation of water balance
The kidney also has a critical role in maintaining water balance and hydration in the body, by regulating the amount of water reabsorbed in the kidney tubules
Chronic Kidney Failure
Diseased kidneys may no longer be able to efficiently remove these waste products. The toxins accumulate in the blood and produce some of the clinical signs of kidney disease (poor appetite, weight loss, increased thirst, vomiting).
The kidneys also become unable to concentrate the urine as they cannot re-absorb as much water back into the bloodstream. This leads to dehydration and more dilute urine being produced (signs of this are increased frequency of urination, and urinating during the night).
Your veterinary surgeon may perform a blood test, to look for the presence of increased levels of waste products (especially urea) in the bloodstream.
Even though your pet may have suddenly started to show signs of kidney disease, we use the term chronic kidney failure because the reduction in kidney tubule function will have progressed over a period of time with the levels of waste products slowly increasing in the blood until they are high enough to produce the clinical signs of disease.
Dietary Management of Chronic Renal Failure
Aims of dietary management:
- To reduce the clinical signs by preventing the accumulation of waste products in the blood
- To slow down further disease progression, by reducing the loss of remaining tubules. By feeding your pet a diet which is lower in protein than normal, you can reduce the build-up of these unwanted waste products e.g. urea
- However, it is important that we do not reduce the level of protein too much, or your pet will not receive enough protein for cell replacement and body regulation
The protein provided needs to be of high quality, to minimise waste and ensure that the amino acids (the building blocks of protein) are provided in proportion to the body’s needs. In order to slow down the progression of the disease, it is essential to reduce the level of phosphorus in your pet’s diet.
When the kidney is unable to remove phosphorus from the blood a series of biochemical pathways lead to the loss of function of more kidney tubules. This results in the kidneys being even less able to remove phosphorus and even more loss of tubule function. By restricting the level of phosphorus in the diet, we can help to slow down these destructive processes.
Special dietary needs
By feeding your pet a diet which is lower in protein and phosphorus than normal, you can reduce the build-up of unwanted waste products (to reduce the clinical signs) and help to slow down the progression of kidney disease. Protein restriction helps to reduce the levels of toxic waste products in the bloodstream.
The level of protein restriction required depends on the severity of your dog’s renal disease.
Low phosphorus, low protein diet or other similar specialist diets are formulated to provide very low levels of phosphorus (to slow disease progression) but with different levels of high-quality protein, according to the stage of the disease being treated. Your veterinary surgeon will recommend the diet appropriate to your pet’s special needs.
Cats are carnivores by nature and need more protein in their diet than the dogs, therefore it is essential that the protein restriction is sufficient to minimise the clinical signs yet still provide all the amino acids that the cat needs.
Dogs and cats with kidney disease sometimes have poor appetites. It is essential that they eat enough to stay at a normal weight, as losing weight can put added stress on their kidneys.
A diet which has a high concentration of calories yet is still low in protein and phosphorus is ideal. Some cats are fussy eaters and kidney disease can decrease appetite, leading to a low intake of food. The food you offer to your cat with kidney disease should, therefore, be particularly palatable.
The inability to concentrate the urine results in the production of larger amounts of more dilute urine. This extra urine production may cause loss of nutrients that are important to your dog’s health, such as B vitamins. Low phosphorous specialist foods are rich in calories with supplemented levels of B vitamins to avoid potential deficiencies.
Care and Attention
There are several general measures which you can take to help your pet:
- If your pet has been prescribed drugs, administer them exactly as advised
- If your pet has been prescribed a Low Phosphorus Diet, feed it exactly as advised. Avoid feeding extra snacks
- Feed meals on a little and often basis, rather than giving one or two large meals in a day
- Offer fresh food at each feeding
- Allow your pet access to clean, fresh water at all times
- Chronic kidney failure is sometimes accompanied by an unwillingness to eat. It may be helpful to warm food to just below body temperature and to attempt hand feeding for the first few days of a new diet
Other Therapy for Renal Disease
In addition to dietary control, you may also be advised on treating your pet with various other therapies.
- Antibiotics are helpful from time to time, to control secondary urinary tract infections.
- Anabolic steroid injections are often useful, especially in cats, as weight loss and poor appetite progress.
- Vitamin supplementation can be useful.
- Blood profile and urine analysis may be helpful from time to time to assess the progress of the condition.