Renal failure is the inability of the kidneys to perform their duties properly and as a result there are excessive levels of urea and nitrogenous waste products in the blood. The build up of urea in the blood is called uraemia.
The kidneys filter the blood and remove all substances which are no longer needed in the body. It also produces the hormone ‘erythropoietin’ which regulates production of the red blood cells in the body.
Acute renal failure (ARF) occurs rapidly and is reversible when appropriately treated. It affects both dogs and cats with middle-aged animals from 6-8 years commonly affected. ARF can happen in very young animals as well as a result of poisoning.
What causes ARF?
There are multiple causes:
- Abnormal blood flow through the kidney. This is common and happens as a result of low blood pressure, lack of blood pressure support while under general anaesthetic e.g. surgeries without the use of intravenous fluids, side effects of drugs (some pain killers and heart medications), heart failure and Addison’s disease.
- Substances toxic to the kidneys such as antifreeze fluid, raisins, grape seeds, snake venom, high calcium levels and lily poisoning in cats.
- Generalised disease affecting the kidneys such as infectious disease (leptospirosis), pyelonephritis (infection of the kidney) sepsis, immune mediated disease (glomerulonephritis), pancreatitis (infection of the pancreas), blood clotting disorders (disseminated intravascular coagulopathy or DIC) and tumours. Blockage of the urethra or bladder with a stone or crystals is commonly seen in dogs and cats in particular.
What are the symptoms of ARF?
There are many and they are very often not specific. Lethargy, vomiting, diarrhoea, dehydration, wobbly gait and increase/decrease in urine production are often seen. Seizures, bad breath, low body temperature, slow heart beat; painful and swollen kidneys can also be found. If the bladder is ruptured a pendulous abdomen can be noticed. In case of urethral blockage a large and often painful bladder can be present.
How is ARF diagnosed?
Blood test confirms the provisional diagnosis immediately. The most common abnormalities seen are high blood urea, creatinine with abnormal potassium levels. Urinalysis can also be beneficial.
Can my pet be saved?
The answer is yes if the diagnosis is quickly established. ARF is a reversible condition. The treatment will depend on the cause of ARF.
The basic principles of the treatment are:
This can be achieved by using kidney diets which are low in protein and high in energy and intravenous fluids. The intravenous fluids work like dialysis in humans and help your pet recover faster. Some pets do not produce any urine due to total kidney shut down and become over hydrated. In these cases urination must be promoted with diuretics and fluids.
- Remove the cause of the problem e.g. if toxicity is the cause remove and/or neutralise residual toxin.
- Support the kidneys until they recover
- Support the rest of the body and make your pet more comfortable by controlling vomiting, using medications to protect stomach lining, resting the stomach until vomiting stops and correct abnormal pH of the blood (acidosis).
Some pets may need more aggressive treatment such as peritoneal dialysis and even kidney transplant is available nowadays.
It is important to know that the treatment of ARF is a complex task and may not be successful. Your pet will have to spend some time in hospital in order to make the treatment work. Also there is a possibility that your pet may need lifelong treatment to keep it stable.
What happens when my pet is discharged from the hospital?
Most pets are sent home on a kidney diet and sometimes with medications if needed. Monitoring is a must and is a crucial part of the treatment. Blood tests are done to monitor the kidney function and see if the treatment was successful or needs more adjustments.
If the patient is stable and doing well, changing a diet to regular pet food may be possible. Once the food is changed additional blood tests are needed to confirm that kidneys are capable of performing their task. If this is not the case a kidney diet must be continued for the rest of the life.