Acute kidney failure in dogs can have numerous causes. However, regardless of the cause, the disease often progresses in a similar pattern.
Symptoms of Acute Kidney Failure in Dogs
Acute renal failure damages the nephrons (the part of the kidney that filters waste products from the blood stream). Damage to the nephrons results in an accumulation of waste products within the dog's blood stream and body (uremia). Uremia in turn leads to the clinical signs seen with acute kidney disease and failure.
Symptoms most commonly seen in canine renal failure include:
- lethargy
- depression
- lack of appetite
- vomiting
- diarrhea
- decreased body temperature
- enlarged or painful kidneys
- blindness or sudden visual disturbances (usually caused by hypertension that leads to retinal detachment)
- coagulopathies and platelet defects that cause excess bruising
- seizures
- encephalopathy
- low blood calcium levels or abnormally high blood calcium levels
- difficulty breathing due to fluid buildup within the lungs resulting from uremia (also known as pulmonary edema)
- heart abnormalities resulting from inflammation of the pericardium due to uremia or from abnormal electrolyte levels
Dogs suffering from acute kidney failure usually have a fairly rapid disease course and weight loss may not be evident simply because there is not enough time involved for the dog to lose weight.
Urine production in acute cases of canine renal failure can be decreased, normal or increased depending on the individual animal and the course of the disease.
Diagnosing Acute Canine Renal Failure
The diagnosis of acute kidney failure in the dog relies heavily on blood and urine testing. Elevations in the blood urea nitrogen and the blood creatinine levels with corresponding dilute urine evidenced by a urinalysis are the trademark characteristics of acute kidney failure.
Other abnormalities which that may be seen in the blood of dogs with acute renal failure include increased or decreased blood calcium levels, anemia, increased potassium and phosphorus levels and derangements of the acid-base balance.
Urinalysis of dogs with acute renal failure frequently reveals an active sediment. Granular casts are considered to be a hallmark of acute renal failure. In addition, proteinuria (protein in the urine) and/or glucosuria (glucose or sugar in the urine) may be present. Calcium oxalate crystals may be seen in the urine sediment of dogs experiencing acute renal failure due to hypercalcemia (elevated blood calcium levels) or ethylene glycol (antifreeze) poisoning.
Complications of Acute Kidney Disease in the Dog
Acute canine kidney disease and kidney failure can result in numerous complications outside of the kidneys. Systemic hypertension (elevated blood pressure) can become problematic in dogs experiencing acute renal disease. Blood pressure should be regularly monitored in these dogs. Central venous pressure may also be measured under some circumstances, but this is more invasive than monitoring the blood pressure.
Dehydration resulting from ongoing fluid losses is a frequent problem in acute kidney disease and affected dogs will likely need to be treated with appropriate fluid therapy to combat dehydration, replace ongoing fluid losses and maintain an adequate hydration status.
Electrolyte disturbances are also common in dogs with acute kidney disease. Electrolytes such as potassium, phosphorus and calcium need to be monitored closely in these dogs. Appropriate intervention may be necessary if these electrolytes become too high or too low. Abnormal electrolyte levels can result in cardiac abnormalities and other complications.
Uremic toxins (the waste products present in the blood stream of dogs with kidney disease) can also cause inflammation in various organ systems, including the gastrointestinal tract, the lungs and the pericardium. The use of medications that protect the gastrointestinal tract may be necessary together with antibiotics, antiemetics (anti-nausea medication) and other medications that combat the effects of these changes.
Urine output needs to be monitored carefully in dogs with acute renal failure as well. For dogs whose urine output is increased, aggressive fluid therapy may be necessary to keep the dog from becoming dehydrated. However, in dogs with low or no urine output, aggressive fluid therapy may lead to volume overload and even death.
Acute canine renal failure can be a reversible disease. A thorough physical examination together with blood and urine tests are necessary to diagnose acute kidney disease in dogs. Once diagnosed, treatment must be tailored to the dogs individual situation. Monitoring blood pressure, acid-base balance and observing for signs of disease in other organ systems such as the heart, lungs and eyes are all part of diagnosing and treating a dog with acute kidney failure.
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