Why Is My Dog 's Urine Positive For Urobilinogen ?

Why Is My Cat 's Urine Positive For Urobilinogen ?

To see what normal blood and urine values are for your pet, go here

For an explanation of causes of most abnormal blood and urine tests go here

To see how tests are often grouped, go here

Ron Hines DVM PhD

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Urobilinogen Levels In Your Pet’s Urine

(also read similar topics: Jaundice, Bilirubin, Icterus Index, Bilirubin in urine)

Urobilinogen is a break down product of the hemoglobin in your dog or cat ’s red blood cells (RBCs).

RBCs live, at the most, four months. When they wear out, they are reprocessed in your pet’s spleen. The iron portion of the hemoglobin in the RBCs is recycled while the heme portion is converted into bilirubin. That bilirubin is normally excreted in your pet’s bile. Some of it that reaches the intestine is then converted into urobilinogen by bacteria in the dog or cat ’s intestine and later reabsorbed (~10%) back into the pet’s blood stream.

Most that was reabsorbed is excreted again by its liver in an endless cycle, but some eventually finds it way into your pet’s urine. Most veterinary hospitals have urine dipsticks with a small square of chemicals that change color in the presence of urobilinogen.

A small amount of urobilinogen in your dog or cat’s urine is normal.

Reasons Why Your Pet’s Urine Urobilinogen Level Could Be High :

Anytime the level of bilirubin being sent to your pet’s intestine is elevated, increased amounts of urobilinogen will appear in its urine as well. You can go to my explanation of the causes of increased increased blood bilirubin levels here.

Health issues that cause large amounts of your pet’s red blood cells to be destroyed in its circulation liberate hemoglobin and result in high blood bilirubin that eventually causes elevated urobilinogen levels in the urine as well.

One of these causes is hemolytic anemia. It is more common in dogs than cats. That form of anemia can be caused by autoimmune diseases, where the pet forms antibodies against its own red blood cells (autoimmune hemolytic anemia) or certain toxins liberated by invading bacteria.

Occasionally, liver disease prevents the liver from efficiently removing formed urobilinogen and re-excreting it into the bile. In those cases, blood levels, an eventually urine levels – of bilirubin rise as well.

Blood parasites of dogs and cats (eg hemobartonella in cats ) are also capable of causing the destruction of large numbers of RBCs releasing hemoglobin, some of which eventually ends up as urine urobilinogen as well.

Toxic chemicals can also cause red blood cell destruction (hemolysis) leading to high urine urobilinogen readings. Fenbendazole has been known to cause this, as has acetaminophen (Tylenol) when given to cats. In some cases, that is because of red blood cell destruction, in others it is because toxic effects on the liver prevent it from re-excreting blood bilirubin effectively.

Reasons Your Pet’s Urine Urobilinogen Level Could Be Low :

Since urobilinogen is formed by your pet’s intestinal bacteria from bilirubin excreted in the pet's bile, anything that interferes with normal bile flow can prevent bacterial urobilinogen formation lowering the amount in the blood and urine.

So a low urobilinogen reading might suggest a bile duct obstruction (obstructive jaundice or gall stone) if other tests agree. However the urine urobilinogen test is not accurate enough to rule out a bile duct obstruction when urobilinogen is found to be present in your pet’s urine.

Tetracycline and other antibiotics can destroy the intestinal bacteria that produce urobilinogen. When that has occurred, your pet’s urine urobilinogen level will be low or absent.

Certain urine acidifiers (eg ammonium chloride, ascorbic acid/vitamin C) can cause falsely-low urine bilirubin readings.

Both the pH of your pet's urine and the concentration (SpGr) of the urine will affect its urobilinogen reading.(ref)

.................... DxMe