Kidney failure in cats: life expectancy depends on the aetiology
What is kidney failure in cats?
Acute kidney failure is characterised by a sudden and persistent decrease in glomerular filtration rate. Its main triggers are renal ischaemia (caused by hypotension, hypovolaemia and shock) and the action of nephrotoxic substances. Glomerulopathy, hypercalcaemia, pyelonephritis, leptospirosis, urinary obstruction and diabetes mellitus may also lead to acute kidney failure. Signs appear suddenly and include those due to azotemia and uremic syndrome.
It must be treated immediately to prevent the onset of complications. Three phases can be distinguished: induction (from the moment kidney damage occurs until dysfunction starts), maintenance (kidney damage established) and recovery.
The treatment of kidney failure in cats tends to be based on the administration of intravenous saline therapy to correct fluid and electrolyte imbalances. Signs of overhydration, urine production and the presence of arrhythmias (due to hyperkalaemia) must be monitored. The prognosis is better in polyuric than in oliguric acute kidney failure. It presents a mortality of 40% or higher with this being affected by the presence of underlying disease, the severity of the azotemia and the signs present at the start of treatment..
In chronic kidney failure, the decrease in kidney function is gradual and is associated with a progressive loss of functional tissue (formed by nephrons). It can be triggered by congenital or acquired nephropathy (secondary to trauma, obstruction, toxicity, idiopathic, autoimmune, infection, cancer or shock with renal involvement) and its incidence increases with age, affecting around 33% of cats aged over 15 years. Once diagnosed, the survival period for the animal varies, although the majority of cats die within two to three years of having been diagnosed (it is responsible for around 3% of feline deaths). Introduction of a renal diet along with treatment doubles life expectancy.
Survival varies depending on the time to diagnosis and the treatment administered, which is why it is important to perform regular analytical checks to detect it at an early point as clinical signs appear much later. It is diagnosed using glomerular filtration rate (GFR) values: a deficit is directly related to the increased serum concentration of stable creatinine, the onset of proteinuria and hypertension. The values and their variations are predictors for survival and will guide the type of treatment to be administered.
Although serum creatinine values are currently used to estimate glomerular filtration rate, it has been shown that mild or moderate decreases in GFR are difficult to detect using current diagnostic procedures. Symmetrical dimethylarginine (SDMA) is a molecule formed by the methylation of arginine, which is released into the blood during protein degradation and is mainly excreted renally. Several studies have shown its strong correlation with glomerular filtration rate, making it a more predictive marker than serum creatinine as it presents greater sensitivity and is also unaffected by excess muscle activity.
Affinity provides professionals with a body evaluation test that can be used to quickly assess an animal’s general state of health. Similarly, the gastrointestinal disease guide will help with the differential diagnosis of these diseases.
