What Veterinarians Learn From a Urine Sample

A urinalysis is one of the most important diagnostic tools in a vet’s toolbelt.

By: alexhg1/123rf
Deep yellow means the urine is concentrated. Your pet may be dehydrated. By: alexhg1/123rf

I was having a veterinary nightmare the other night.

Stuck in an episode of veterinary Survivor, I was 44 nautical miles south of Cape Disappointment with a sick dog named Spike. My challenge was to choose 1 and only 1 laboratory test to diagnose poor old Spike. What do you think I picked? I chose to run a urinalysis.

The kidney is an amazing organ. A thorough urinalysis is like taking a magical looking glass and spying into that kidney. But it’s much more than that. A good urinalysis gives us information into many involved metabolic pathways in the body.

Let’s start with looking at old Spike while he lifts his leg. Sometimes the naked eye is all that is needed to pick up on a developing health problem. I check the color, the volume and the consistency of the urine, and it can tell me quite a bit about a dog’s condition.

Deep yellow, light yellow, greenish urine, reddish urine, sticky urine, a different-smelling urine: These are all helpful hints you might pick up on before your pet is showing any other signs of being sick. Get that urine sample to the vet! (Here are some tips for collecting a sample.)

It’s snow season back in the Northeast, so I’m hearing a lot of “My dog peed in the snow and it was red!” Blood in the urine may have been going on for a while, but thanks to the white stuff on the ground, we can now get to work diagnosing the problem.

Urine as a Paint-by-Numbers Exercise

Let’s say Spike’s urine looks particularly dark — almost too dark. This could be normal or mean he’s a bit dehydrated.

If it has an orange tinge, it could mean that Spike is beginning to get jaundiced, which could indicate a liver problem. If it appears more red than orange, meaning blood in the urine, we need to finish our analysis.

  • Deep yellow to yellow-orange: concentrated urine; bilirubin (liver, gallbladder)
  • Greenish: bilirubin
  • Red to orange to pink: blood in urine (hematuria)
  • Milky white: fat (lipiduria) or pus (pyuria)

For your everyday challenge of keeping your pet healthy, trust your powers of observation. If you think there’s something funky with the urine, have it checked out.

Specific Gravity of Urine

Testing the specific gravity measures the urine’s concentration. Is the urine dilute, like water, or concentrated? Urine concentration is an important aspect of overall health.

The specific gravity of the urine correlates to how much water the pet is drinking and how well the kidneys are concentrating that water. Thirst, what causes it and what the kidneys do with fluid intake are very important indicators of many possible illnesses and metabolic conditions.

The Dipstick

The dipstick is not a sequel to Dumb & Dumber. As part of a urinalysis, a few drops of urine are placed on a lab strip called a dipstick and, after 60 seconds, we learn a lot about your pet’s urine.

This simple test measures the presence of certain substances and characteristics of the urine:

  • Blood: can indicate infection, inflammation, tumor
  • Glucose: indicates diabetes
  • Protein: indicates inflammation or certain diseases
  • pH: if the pH is not in the normal range, it can promote urinary infection or bladder stone development
  • Ketones: these should never be present in a healthy animal
  • Bilirubin: early indication of liver or metabolic disease

Urine Sediment

When you spin urine in a centrifuge, all the interesting things that may be in that urine settle down into the bottom of the tube. This is called the sediment. You examine the sediment with a special lab stain under a microscope and discover lots about the patient.

You need a very good microscope and a trained eye to analyze a urine sediment properly.

  • Cells: A normal urine sample should not contain many cells. If white blood cells, red blood cells or transitional cells are present, the urine is not normal and disease is indicated.
  • Casts: Casts look like little tubes or cylinders. This is because they are castoffs from the renal tubules. When a kidney sends a cast into the urine, it most often means the kidney is angry about something. The cast is highly suggestive of an inflammatory condition.
  • Crystals: These beautiful little structures look exactly like their name suggests. There are several kinds of crystals found in urine, and they can be identified by their shape and properties. Although some crystals can be found in normal urine, crystals indicate you need to look further to find out if they are significant. They may indicate the presence of bladder stones or infection.

Tests Beyond a Urinalysis

Specialized tests on urine can be of great value if the patient’s symptoms or an abnormal urinalysis tells you to look further. These are not part of a standard urinalysis.

  • Culture and sensitivity: If there is a serious infection in the urine or if your patient is compromised with a disease such as diabetes, a urine sample taken directly from the bladder can be cultured to see if pathogenic bacteria are present. Then a sensitivity can be run to see which antibiotic is the best choice to combat the infection. In other words, the urine is cultured to see if bacteria grows, and then we find out if that bacteria is sensitive to certain antibiotics.
  • Urine protein: Tracking excessive protein in urine is important in certain disease processes. Over time, it gives us important diagnostic information and is a noninvasive test.

In the video below, Suburban Animal Clinic (Columbus, Ohio) explains more:

http://youtu.be/ojPAmwle9sY

Did I Win the Challenge?

Many of my cases are like Survivor challenges because I’m often not able to run all the diagnostics that would help me solve the case. If your veterinarian is pressing you to bring in a urine sample or emphasizing that a urinalysis is part of a thorough medical workup, it’s true.

Stranded off the great Cascadia Basin, as I look into Spike’s sick eyes and try to win the Survivor challenge and return Spike to health, I’d check his urine first.

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This pet health content was written by a veterinarian, Dr. Debora Lichtenberg, VMD. It was last reviewed Dec. 17, 2014.

Dr. Debora Lichtenberg, VMD

View posts by Dr. Debora Lichtenberg, VMD
Dr. Debora Lichtenberg, VMD, is a small animal and exotics veterinarian who has split her time between a veterinary practice in Pelham, Massachusetts, and her studio in New York City. Dr. Lichtenberg is a graduate of the University of Pennsylvania School of Veterinary Medicine with 30 years of experience. Her special interests are soft tissue surgery and oncology.

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