Chronic renal failure is the inability of the kidneys to perform their task for a long period of time. It usually occurs slowly and there is a chronic increase in urea and nitrogenous waste (uraemia) products with a lost ability to concentrate the urine. The latter leads to severe dehydration, which can be fatal.
CRF is an irreversible process and usually terminal disease when compared to Acute Renal Failure (ARF). There is not much that can be done about it apart from slowing down its progression as much as possible.
CRF is a disease of older cats and dogs. In cats, Persians and Abyssinians are more often affected than others while Bull Terriers, Basenjis, Cairn Terriers and German Shepherds are commonly affected in dogs.
How does CRF happen?
Most cases of CRF are idiopathic which means we do not how it happened. Most causes of prolonged ARF can cause CRF. Diabetes Mellitus, FIP, tumours, immune mediated disorders (amyloidosis) and familial disease such as PKD (polycystic kidney disease) in cats may also cause CRF.
What are the symptoms of CRF?
They may go unnoticed but, if present, the most common ones are lethargy, excessive thirst/urination, vomiting, loss of condition and muscle wasting. Excessive salivation (due to mouth ulcers), bad breath (due to uraemia), high blood pressure, blindness (due to degeneration of retina) and diarrhoea or constipation can also be seen.
How is CRF diagnosed?
Blood tests usually give us enough information to make a diagnosis. Urinalysis can also be useful. Excessive increase in blood urea nitrogen and high phosphorus and potassium are common findings. The pet may be anaemic as a result of stomach ulcers and/or lack of erythropoietin (hormone which stimulates the production of red blood cells in the bone marrow and is produced by the kidneys).
Is there a treatment for CRF?
CRF is a terminal disease and our goal is to keep your pet comfortable and extend its life. If the pet is in uraemic crisis it needs intravenous fluids and hospitalisation. Stable cases are treated as outpatients. Diet is an important part of the treatment and it involves reduced protein levels, increased carbohydrates and is mildly alkalising (to offset increased acidity of the blood). Unrestricted water access is important.
The pet will need long-term kidney diet or a special homemade diet if picky. Some need additional treatment such as:
1. Subcutaneous fluids to maintain hydration
2. Medications to stop vomiting
3. Maintain electrolytes balance (monitor and adjust the levels of potassium in the body)
4. Treat high blood pressure if any
5. Control high levels of phosphorus with phosphate binders
6. Erythropoietin to control anaemia if present and severe enough
What is a long-term prognosis?
This depends on the severity of CRF. In severe cases the disease progresses rapidly and is often unstoppable. Mild cases can be supported for a long period of time, up to a couple of years. The cornerstone of the treatment is a kidney diet that is less palatable due to the low protein content. It is worth trying different brands because some are more palatable then others.
As previously mentioned homemade diets are available and effective but require commitment and there is no guarantee it will work. The basic principle of a homemade diet is equal to a commercial kidney diet – a low protein and high carbohydrate ratio.
Medications may be needed for additional support. It is a fact that the CRF will progress and this is why your pet needs frequent monitoring to make sure there are no other complications. Most of the pets with CRF need 3-6 monthly checkups assuming they are doing well. Out vets will advise you on what could work best for your pet.