Chronic vs. Acute Kidney Failure in Cats

Treating kidney failure in cats begins with identifying the specific disease responsible for their condition. One of the most important distinctions is between chronic and acute feline renal failure. Both involve the breakdown of the kidneys, which are responsible for processing and filtering waste, and regulating blood and water levels. A cat that suffers from either form of this life-threatening illness needs immediate medical attention.

However, the kind of treatment and after-care prescribed depends significantly on whether the source of feline kidney failure is chronic or acute. There are a number of laboratory tests veterinarians use to make a diagnosis. Here are some of the key differences between these two serious forms of cat kidney disease and a few of the methods used to identify them.

Chronic Renal Failure Symptoms and Tests

Chronic Renal Failure (CFC) is caused by the long-term deterioration of the kidneys. This occurs when small structures in the feline kidneys, called nephrons, gradually die off, leaving the organs unable to filter waste and regulate fluids. The exact cause of CFC is unclear; however, many animal care experts believe inadequate nutrition is a leading contributor to the disease. Years of consuming commercial food containing byproducts, carbohydrate fillers and low-quality protein are thought to cause damage to some feline urinary systems.

Common symptoms of CFC include:

  • Excessive urination and thirst
  • Loss of appetite
  • Fatigue
  • Weight loss
  • Vomiting
  • Bad breath
  • Drooling
  • Dehydration
  • A dull coat

Diagnosing chronic renal failure begins with a thorough physical exam and an intake of the patient's medical history. Based on the veterinarian's evaluation, a series of laboratory tests may be ordered to confirm a CFC diagnosis. Urinalysis is used to measure the concentration of minerals and chemicals in the urine. Diluted urine can indicate the kidneys' decreased ability to filter waste products. Blood chemistry tests are another significant testing tool. A complete blood count shows the number of red and white bloods cells, which are often affected by kidney disorders. Depleted levels of red bloods can cause anemia, a common condition among chronic renal failure cats.

Other important tests indicate the amounts of creatinine and blood urea nitrogen (BUN), two naturally occurring waste products, in the bloodstream. Increased levels of creatinine and BUN are among the strongest indicators of chronic kidney failure. Additional tests sometimes used to test for feline CFC are urine protein to creatinine ratio, blood pressure and X-rays of the abdominal area.

Acute Renal Failure Symptoms and Tests

Acute Renal Failure (ARF) happens suddenly due to trauma, poisonings or illness affecting the kidney area. It can occur in cats of any breed or age. Accidental ingestion of anti-freeze, disease, infection and urethral obstructions are among the most common causes of this life-threatening kidney condition. Acute renal failure occurs rapidly in cats, so immediate medical attention is required to help avoid permanent injury or death. Some cases of ARF may also be reversible if diagnosed and treated early enough.

Key signs of ARF include:

  • Lack of coordination
  • Refusal to eat
  • Pain and straining during urination
  • Vomiting
  • Weakness
  • Disorientation
  • Bad breath
  • Seizures

As with CRF, a veterinarian suspecting acute renal failure will make her diagnosis beginning with a complete physical exam and review of the cat's medical history. Additional tests may also be required to help determine the cause of the disorder. Like CRF, acute renal conditions typically create increased creatinine and BUN levels in the blood. However, a blood count may help distinguish acute from chronic renal failure. Unlike CRF, red blood cell levels are generally increased in acute kidney failure cats.

In addition, ARF tests include screenings for infections and the presence of ethylene glycol, or antifreeze. Veterinarians may also recommend ultrasounds of the abdominal area or a kidney biopsy as part of the diagnostic process.

Whether the case is sudden or gradual, dealing with feline renal failure can be a stressful and unnerving experience. However, knowing the signs of chronic and acute kidney failure can help cat owners, particularly in emergency situations. The more you know what to look for regarding these two serious kidney conditions, the greater amount of information you may be able to give your veterinarian.