Preventing chronic renal failure
Apr 01, 2002
Conditions affecting renal function An important aspect of preventing chronic renal failure is recognizing conditions that may compromise renal function and administering prompt and adequate treatment. For example, dehydration results in decreased renal perfusion and compromise of renal function. Dehydration often occurs with gastroenteritis, pancreatitis, heat stroke and infectious diseases such as pyelonephritis, to name a few. It is likely that chronic renal failure results from repeated and probably different episodes of damage to the kidneys in many patients. Chronic renal failure may also occur as a result of acute renal failure where damage has exceeded the regenerative capacity of the kidneys. Even with successful treatment of the acute renal failure, the dog or cat may remain in renal failure. Such conditions include, but are not limited to, ethylene glycol intoxication, pyelonephritis, leptospirosis and immune-mediated renal diseases.
Chronic renal failure occurs predominantly in older dogs and cats. Because of this, extra-renal diseases may create an acute-on-chronic situation. As mentioned previously, any disease resulting in dehydration may result in worsening azotemia or progression of chronic renal failure. Older animals undergoing anesthesia for elective or necessary procedures should receive fluid support in order to minimize hypotension and hypoperfusion. Examples include dental prophylaxis and surgical removal of growths.
Nephrotoxic drugs Administration of drugs that are nephrotoxic should be used cautiously, if at all. Non-selective, non-steroidal anti-inflammatory drugs may be administered because of osteoarthritis in older animals. These drugs may decrease production of renal vasodilatory prostaglandins, thus, increasing the risk for renal failure or for an acute-on-chronic episode. Enalapril, often used because of cardiac disease, also may decrease renal function. Catabolic drugs, such as glucocorticoids or chemotherapeutic agents, may cause protein catabolism resulting in increased azotemia. Some drugs, such as certain antibiotics, cause nausea and vomiting, which may result in dehydration. Therefore, administrating any drug to an older animal should be carefully thought out and consideration given to risks and benefits of administering the drug.
Bacterial urinary tract infection Bacterial urinary tract infections may result in decreased renal function. If the bacterial urinary tract infection becomes established in the kidneys, then renal function may be compromised or an acute-on-chronic episode may occur. Animals with chronic renal failure are at greater risk for developing bacterial urinary tract infection because of isosthenuria and alterations in other host defenses due to the renal failure. In many older animals, especially cats, bacterial urinary tract infections are often not associated with clinical signs such as hematuria, dysuria and pollakiuria. Prophylactic use of antibiotics should be avoided unless necessary because it may result in highly resistant bacteria. In addition to their catabolic actions, glucocorticoids, whether endogenously produced in excess or administered exogenously, increases risk for bacterial urinary tract infection.