KIDNEY DISEASE
CHRONIC RENAL FAILURE The most common kidney disease seen in older pets (especially cats), is chronic renal failure. This is a progressive disease that can last for months to years, but is ultimately fatal. Although there is no “cure”, the signs of renal failure can be reduced to improve the quality and longevity of an affected pet.
What do the kidneys do?
Kidneys have 3 major functions:
- Conserve / regulate water and electrolyte balance in the body
- Excrete waste products
- hormone production Kidney failure involves some loss of all 3 functions.
What causes renal failure? The cause for each individual case is not usually known.
Domestic cats begin life with around 400,000 nephrons (the tiny filters inside the kidneys). Nephron numbers gradually reduce with age. Genetics, infection, blood loss, shock, drugs, toxins, cancer, and “wear and tear” have all been suggested as causes for nephron loss. Most cats over 15 years of age have some degree of renal failure.
Once kidneys have lost 66% of there nephron population their ability to conserve water is impaired and early signs (increased drinking) appear.
When 75% of the nephrons have been destroyed, then second function of waste product excretion is lost. Signs of illness appear, and changes are detectable on blood tests.
As disease progresses, the third function of the hormone production is lost and serious illness occurs.
What are the signs of renal failure?
Signs can include:
- Increased drinking and urination
- Reduced appetite, weight loss
- Lethargy / depression / confusion
- Poor coat condition
- Vomiting, diarrhoea or constipation
- “Lip smacking” (nausea and a dry mouth cause cats to smack their lips when presented with food)
- Mouth Ulcerations
These signs are due to a combination of dehydration, anaemia, electrolyte imbalances and toxin overload.
How is renal failure diagnosed? Renal failure is most commonly diagnosed with a combination of blood and urine tests. The most common findings on these tests are an increase in serum UREA and CREATININE, and a low urine specific gravity. These are by-products of protein metabolism which should be cleared by the kidneys (so high levels may be an indication that the kidneys are not working properly). Other changes can include electrolyte and mineral imbalances and anaemia.
Occasionally, blood pressure measurements, radiography, ultrasonography, or kidney biopsy is necessary to give further information on underlying cause, and prognosis.
What can be done? Unfortunately renal failure is progressive, and a kidney transplant would be the only way to restore kidney function once it is lost. This is not a reasonable option for most pets. There is however a lot that can be done to alleviate signs, and support the remaining kidney tissue.
FLUIDS – pets with renal failure should always have free access to water. In times of illness, your vet may also suggest intravenous or subcutaneous fluids to help “flush” toxins from the body and treat dehydration.
DIET – Prescription “kidney diets” are available that have very high quality, but low quantity protein, and reduced in salt and phosphorus. These diets result in less metabolic waste for the kidneys to clear. Moist or tinned foods also help maintain hydration.
MEDICATIONS – your Vet may be able to prescribe medication to assist with blood pressure control (to reduce the workload of the kidneys); or to stimulate appetite; or replace lost vitamins and electrolytes.
REGULAR CHECK-UPS – due to the complex changes in a variety of body systems, the ideal treatment for your pet is likely to change over time, and regular reassessment should be discussed with your vet.
