Metabolic acidosis in renal failure is an example of regulatory failure. Decreased concentrations of these compounds contribute to several abnormalities of renal failure, including secondary hyperparathyroidism and anaemia. The loss of urine concentrating ability is primarily due to tubular damage. Causative factors include increased urea concentrations in saliva, hypergastrinaemia, and stimulation of the chemoreceptor trigger zone by uraemic toxins. In addition, further suppression of bone marrow may occur because of accumulated uraemic toxins.
Metabolic acidosis is a common finding, particularly in cats.
It may be an important factor in progression of disease. It arises primarily from reduced ability to excrete hydrogen ions, because of reduced renal mass. Acidifying diets should be avoided in animals with chronic renal failure. Hyperphosphataemia may contribute to the development of renal secondary hyperparathyroidism, soft tissue calcification, and potentially, to the progression of renal damage. Hypertension is probably quite common in dogs and cats with chronic renal failure, however, the severity of the hypertension is generally mild, and it may be of limited clinical significance.