Kidney Disease

Kidney (or Renal) disease or failure are general terms used to describe problems with the kidneys and their ability to function properly. Kidney disease is one of the most common problems that veterinary surgeons see in cats and it is thought that the reason we see so many cases is because our beloved pet cats are living so much longer these days, thanks to great care from owners as well as advances in nutrition and veterinary treatments. 

The kidneys are amazing organs, they are responsible for maintaining the normal composition of the blood by filtering waste products from the body such as urea, ammonia, drugs and toxic substances. They also keep the volume of water in the body constant, help regulate blood pressure, maintain calcium levels and produce a hormone that encourages red blood cell production. The kidneys filter waste through thousands of tubes known as nephrons; if these become damaged it makes it more difficult for the kidneys to filter out the toxins from the blood stream which will make the cat feel very unwell and cause symptoms such as

• Increased thirst
• Changes to urination – increased, decreased  (perhaps toileting in the house)
• Decreased appetite
• Nausea & Vomiting
• Weight loss
• Dehydration
• Diarrhoea
• Hunched position (pain)
• Poor coat

If your cat is showing any of these signs then you should have him or her checked by a vet as soon as possible; it is also a great help if you can get a fresh urine sample from your cat, as this simple and inexpensive test can give your vet some basic information about how well the kidneys are working.

Common Causes Of Kidney Disease

One of the most common reasons for kidney disease and deterioration is the age of the animal, but kidney disease may also happen very suddenly (acute kidney failure), depending on what has caused it to happen.

Chronic kidney disease: A loss of kidney function that occurs over time, that may be caused by old age and general wear and tear, disease causing deterioration, or a previous problem of acute renal failure.

Acute kidney disease or failure: The function of the kidneys is affected very suddenly and may be caused by an infection or the ingestion of a toxic substance such as lily pollen or antifreeze.

Hereditary/Congenital Problems: These are present at birth, but may not always be discovered until the animal is older. Examples of these problems include,

• Renal dysplasia – One or both kidneys are small in size and do not mature or function properly.
• Polycystic kidneys – The kidneys are bigger than normal and develop cysts inside them

Infections: Bacteria entering the blood streams via infection or from dental disease, can cause problems in many organs including the kidneys.

Stress on the kidneys: This is usually as a result of other illnesses or problems such as hyperthyroidism, heart problems, high blood pressure, diabetes, urinary tract problems, cancer and trauma such as a road traffic accident.

How Kidney Disease Is Diagnosed

1. Examination: The vet will give the catt a thorough examination, taking into account any of the clinical signs and symptoms.
2. Urinalysis: This relatively inexpensive test can give the vet a basic idea of how well the kidneys are functioning and indicate a problem, but is not sufficient in itself to diagnose kidney disease.
3. Blood Test: This can give the vet a really good idea of how well the kidneys are functioning.
4. Ultrasound and/or X-ray: The vet will be able to look at the size and shape of the kidneys on both X-ray and ultrasound. Ultrasound may also be used to see the density of the kidney and to guide a needle for a biopsy of the kidney.

Routine Treatment Of Kidney Disease

1. Fluid Therapy

A cat with kidney damage or failure cannot concentrate their urine properly, which means that too much fluid is passed out of the body and it is very easy for them to get dehydrated and suffer from a buildup of toxins in the blood stream. Initially your cat may need to stay at the veterinary practice to be given intravenous fluids via a drip for a couple of days, in order to rehydrate them and also so that the vet can monitor them properly.

Some cats with kidney disease/failure will require fluid therapy on a daily or slightly less frequent basis. Fortunately, as long as they are reasonably well hydrated, a bolus of fluid can be injected subcutaneously (under the skin) as needed, rather than them needing an intravenous drip. At my veterinary practice, we like to show willing owners how to do this themselves, so that their cat is able to stay in the comfort of their own home when receiving treatment and, once they have got the hang of it, many owners are happy to do this for their cat if it means a few less trips to the vet!

2. Veterinary Prescription Diet Foods

These are recommended by the vet because they are specially designed to help your cat’s kidneys function as well as possible when damaged. These veterinary diets have been proven to significantly benefit cats with kidney disease in terms of decreasing the levels of toxins in the bloodstream and improving the cat’s condition.  A renal diet must contain

Low Amounts of High Quality Protein – Cats are obligate carnivores so they need to eat a diet consisting mainly of protein and fat. In healthy cats the dietary protein is broken down in the body to help it function and during this process, any toxic by-products that are produced by the protein breakdown are filtered by the kidneys and then excreted in the urine. However, the kidneys of a cat with kidney disease/failure are not able to filter toxin by-products efficiently which can quickly lead to a build up of uraemic toxins in the blood, making the cat feel very sick. Veterinary Prescription Kidney Diets are low protein to minimize the production of toxins and the protein is of a very high quality so that what little is utilised can do its job properly.

Restricted Phosphorous – Phosphorous is normally excreted from the body in the urine, but, in a cat with kidney disease, it can build up to toxic levels within the body as it is not filtered out. High amounts of dietary phosphorus will accelerate kidney failure, so reducing the phosphate levels in the diet will help to protect the kidneys from further damage and slow the progression of kidney disease.

It can be tricky to encourage cats to try new foods, especially those with kidney problems as they are also often feeling nauseous and quite poorly before their treatments have started to take good effect. If your cat has been given a special diet, try warming it slightly to make it more appealing. I also recommend trying (and using) several different brands of veterinary prescription kidney diets, so that your cat has a choice if he or she is a bit fussy; your vet should be able to get these diets in for you, or once your cat has been diagnosed you may be able to order the kidney diets from an online veterinary pharmacy. Current veterinary prescription diets include

• Hills k/d
• Royal Canin Renal Support
• Eukanuba Renal
• Purina NF Renal Function
• Specific Feline FK

3. Medications

Your vet will recommend specific medications to help with kidney function and to treat underlying infections and side effects such as nausea and vomiting; they may also prescribe vitamin and mineral supplements to replace what is being lost by the body. It is vitally important that you discuss any ‘over the counter’ supplements that you want to give your cat with your vet as some may not be suitable at all and may even cause more damage.

4. Regular Monitoring and Blood Tests

Your vet will ask to see your cat on a fairly regular basis in order to monitor his or her condition and make adjustments as necessary to fluid therapy, diet and medications. Blood tests, blood pressure monitoring and weight checks will be necessary to ensure that your pet is doing well on the prescribed treatments and to monitor for any further decrease in function of the kidneys. Monitoring visits may initially be as frequent as every two to four weeks, but once your cat is stable they are often  reduced to every two to three months.

Other Possible Treatments For Kidney Disease 

If these treatments are available to help your pet, they will often need to be referred to a specialist veterinary practice to receive them.

• Stem Cell Therapy –  The idea with this treatment is that the adult stem cells help body organs to regenerate and repair. The procedure involves giving a general anaesthetic to the patient in order for the vet to harvest fat from the abdomen; this fat is then sent to the laboratory where the stem cells are isolated, concentrated and then returned to the veterinary practice. The stem cell therapy is then administered to the patient intravenously.  Most veterinary practices could perform this therapy, but it is generally left to specialist veterinary practices due to the invasive procedures and high costs involved.
• Dialysis – This is process that cleanses the blood of toxins and is commonly used in human patients. The dialysis machine filters the blood and rids the body of harmful waste, extra salt, and water. Dialysis is an intensive and expensive procedure that is not widely available in the UK at the moment, although some veterinary hospitals may be able to provide treatment.

While kidney transplantation is a fairly standard procedure for humans, it has proved to be extremely expensive and not very successful in animals.  There is also a big question about whether it is and ethically acceptable procedure because the donor and recipient animals are unable to give consent. Kidney transplant treatment is not currently available in the UK.

The Outlook For Pets With Kidney Disease

Advances in veterinary medicine and treatments mean that there is now a great deal that vets and owners can do to help a pet with kidney disease to feel better, it also means that many pets with chronic kidney disease go on to live for several more years after their initial diagnosis. Of course this will also depend on the cause and severity of the kidney damage before diagnosis, but with early and intensive treatment, some forms of acute renal failure may even be reversible.