Understanding your Pet’s Labwork: Urinalysis
Sometimes you’ll know when your pet needs their urine checked - if you’re seeing blood in the urine, straining or pain on urination, or accidents in the house. But we frequently check urine on pets before there have been any changes that you would have seen at home because it can give us information about the kidneys, adrenal glands, or systemic inflammatory processes.
Let’s go over the parts of the urinalysis and what they tell us.
USG/USPG: Urine specific gravity
This tells us about the urine concentration. The kidneys function to eliminate wastes to be excreted through the urine, and they also help balance the amount of water in the blood and keep it at an appropriate level.
When they’re functioning normally, they get rid of more water in the urine if the pet is well- or over-hydrated. When that pet is less hydrated or dehydrated to any degree, the kidneys conserve water, which results in more concentrated urine.
However, if the kidneys aren’t functioning properly, or if another factor present is incorrectly telling the kidneys not to conserve water, the pet can’t concentrate their urine, and we will see dilute urine. Normal urine concentration can vary from day to day and even throughout the day, so seeing dilute urine once isn’t necessarily a problem.
But if we also see changes to kidney values, OR if that urine is persistently and inappropriately dilute, then that is something that should be further evaluated. It may be an early sign of kidney disease, adrenal disease, diabetes, or many other disease processes.
Urine protein
A small amount of protein getting into the urine might be normal, but when we are seeing a lot of protein, this might indicate kidney disease such as inflammation or cancer, Cushing’s disease, infectious disease like Lyme, or other. At first there frequently aren’t any clinical signs associated with proteinuria, but if it continues or progresses, it can result in an overall decrease in blood protein levels. When this gets bad enough, we can see fluid leaking from the blood into the chest or abdomen, abnormal clot formation, and decreased ability to heal - all of which can be very dangerous for your pet.
Urine glucose
The most common cause of glucose in the urine is diabetes, so elevated levels should be further investigated. In rare cases, inflammation or other disease can cause blood sugar (glucose) to leak into the urine without having elevated glucose within the blood itself.
Urine ketones
Ketones in the urine can be seen in a scary sequela of uncontrolled diabetes, called diabetic ketosis or diabetic ketoacidosis (DKA). This can be fatal, which is why we frequently check urine on any diabetic pet who isn’t feeling well.
Urine pH
Urine pH can vary throughout the day, so changes to urine pH alone don’t usually necessitate treatment or further diagnostics. However, a high urine pH can be associated with infection, and can be associated with formation of certain bladder stones called struvites. Meanwhile, a low urine pH can be associated with calcium oxalate bladder stones. So we may monitor the pH in pets who already have a history of bladder stones, to make sure we’re effectively preventing further stone formation.
Bilirubin
Abnormally high urine bilirubin may be seen with internal red blood cell destruction, which can be very dangerous.
Urine sediment exam
This is when we look at the urine under the microscope. Here, we look for red blood cells, white blood cells, urine crystals, or casts. Red blood cells in the urine can be associated with infections, inflammation, stones, or cancer within the bladder or kidneys. White blood cells are seen primarily with infection or inflammation. Urine crystals can tell us about stone formation, and casts can tell us about kidney damage or inflammation.
As you can see, a urinalysis gives us a lot of information about the urinary tract, from the kidneys to the urethra. But it also can tell us a lot about general health, including things that might not be obvious even to a very astute owner, until a disease has progressed beyond when it can easily be treated. This is why we often recommend a urinalysis, especially in older patients, even when they seem to be doing very well at home!
Written by Dr. Lauren Pike