Cats are so called ´obligate carnivores´. That means that animal protein and various amino acids, are vital to the cat.
Precursors of uraemic toxins are produced when intestinal bacteria digest some of these amino acids (tryptophan, phenylalanine and tyrosine) as a part of the cat’s normal protein metabolism. The precursors are absorbed and transported to the liver where they are metabolised into uraemic toxins, indoxyl sulphate and para-cresyl sulphate. These toxins are then excreted via the kidneys without causing any harm.
With increasing age, the kidney function decreases and that might lead to accumulation of indoxyl sulphate that may affect kidney health.