The kidney's main function in a dog is to filter the blood from toxic buildup and remove the waste through excretion, commonly called urination. Creatinine is a toxic metabolite found within this toxic buildup and is used as one of two key indicators to measure kidney functions in dogs. A certain level of creatinine is expected to be in the blood of a dog and a range of "normals" has been established to recognize this. Any variation above or below this normal range indicates a problem with the kidneys which may require further diagnostic work and treatment.
Normal Creatinine Levels in Dogs
Symptoms of Elevated Creatinine
Symptoms of kidney failure in dogs will normally manifest with a dog drinking excessive amounts of water, urinating a lot, loss of appetite, vomiting, weight loss, dehydration, and unkempt fur appearance. These symptoms will usually start to appear gradually, though the owner may not notice them for some time. Usually, by the time an owner notices that there is a problem, the disease is well under way and there have already been blood chemistry changes, most notably, an increased creatinine level.
The normal levels of creatinine in a dog are 0.6 to 1.2. In order to determine what the dog's creatinine level is, a small sample of blood is drawn and placed into a special "separator" vacuum blood tube. The blood is allowed to clot and is then "spun down" in a centrifuge, allowing the red blood cells and platelets to fall under the separation media, leaving only the serum for testing.
A sample of serum is placed into the blood chemistry panel machine and the machine goes to work, measuring the different levels of specific indicators for a number of internal organ systems, including BUN (blood urea nitrogen) and creatinine to measure kidney function. When the test is complete, a result page is printed showing the normal ranges for each function tested and the sample levels.
What it Means
A creatinine level of greater than 1.2 will indicate that the kidneys are not functioning properly and are not removing this substance from the blood at a high enough rate to keep the dog healthy. Usually, a dog will have compensated for the loss of kidney failure by drinking more water and producing more urine to flush the creatinine from his system, therefore making it difficult to diagnose kidney failure by bloodwork alone. At least 2/3 of normal kidney function will have been lost before the creatinine level will begin to rise.
Treatments for kidney failure include starting the dog on either intravenous fluid or subcutaneous fluid therapy in an attempt to lower the toxin concentrations in the blood. This approach is usually successful for awhile, until the kidneys degrade to the point that they can no longer filter the blood at all. Vitamin injections are given in an effort to support kidney function and the diet is changed to include less protein. This is thought to be easier on the kidneys and slows the progression of the disease.