Introduction
Kidney disease in dogs is most often conclusively diagnosed through blood and urine tests. In some cases, ultrasound can be used to determine the extent of the disease.
Diagnosing Kidney Disease in Dogs
Advanced kidney disease causes a number of symptoms to develop, but urine and blood tests are needed to positively diagnose the condition. Creatinine and blood urea nitrogen (BUN) are the two main blood components that are tested. Urea is produced by the liver, and it is filtered out of the bloodstream by the kidneys. High levels of urea indicate reduced kidney function. Creatinine is a compound that is produced by muscle, and the kidneys also filter creatinine out of the bloodstream. As with urea, high levels of creatinine in the blood occur when kidney function is reduced.
A urinalysis cannot be used on its own to diagnose kidney disease in dogs, but it can be used as a first line test to see if further blood tests are warranted. Two main components of a urinalysis are measured to indicate kidney function: specific gravity and the presence of protein. Healthy kidneys are able to concentrate urine, and healthy urine has a certain level of specific gravity that occurs when the urine is concentrated. Especially dilute urine may point toward possible kidney disease. Proteins in the urine may occur if the kidneys are infected, and the presence of proteins in the urine may also indicate kidney disease.
While blood and urine tests can be used to diagnose kidney disease, an ultrasound may be performed in order to see exactly how much damage has occurred to the kidneys. Ultrasound may also be used to see whether only one kidney is affected by disease or if both kidneys are affected.