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Causes of Reddish, Dark Brown Urine in Dogs

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We all know that the normal color of urine is yellow, and therefore, it's normal for dog owners to be concerned about reddish, dark brown urine in dogs, but what causes a dog's urine to become this color? If your dog's urine appears brown, the best thing to do is to collect a urine sample and bring it along with your dog to the vet as soon as you can. Your vet may or may not use that sample to analyze it, but it allows him to observe the unusual color. There are various causes of brown urine in dogs, but they all require proper testing and diagnostics and your dog should be treated accordingly based on your vet's findings.

dog urine sample

Investigating the Issue

What causes brown urine in dogs? Dog owners may often wonder where the brownish tint comes from and there are several possibilities. In order to understand what causes the brown coloration in the first place, it's necessary to get acquainted with potential pigmented substances that may be present in the dog's urine and that may be responsible for causing the color changes.

One possible substance is myoglobin, an iron- and oxygen-binding protein that is found in a dog's muscle tissues. The presence of myoglubin in dog urine is known as myoglobinuria. 

Another possible substance is the presence of hemoglobin, a red protein found in red blood cells and that's responsible for transporting oxygen in the dog's blood. The presence of free hemoglobin in a dog's urine is known as hemoglubinuria and it is seen as a result of the destruction of red blood cells.

Blood in a dog's urine may also sometimes cause a brown, reddish tint. The presence of blood in dog's urine is known as hematuria and in this case the red blood cells are intact in the urine.

Finally, another possible substance that can make its way to the dog's urine is bilirubin, the useless and toxic breakdown product of hemoglobin. The presence of bilirubin in a dog's urine is known as bilirubinuria.

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While the color in most foods and drugs are lost during digestion, at times, the dark color of urine may be due to some medications or some ingested substances. Abnormal urine colors may be also due to ingestion of toxins and drugs (acetaminophen, rat poison).

A Sign of Dehydration

Brown urine in a dog can be a sign that his urine is concentrated which can be seen in a dehydrated dog. Urine generally tends to have a much darker color urine in the morning, explains veterinarian Dr. Andy.

Generally, the dark urine found in a dog suffering from dehydration will soon resume its normal color once the dog is hydrated once again either by allowing the dog to drink or having the vet provide fluids under the skin subcutaneously or intravenously.

This presentation may be therefore temporary at least until the dehydration issue is corrected. It's important though to investigate the underlying cause of the dog's dehydration, which may be secondary to other medical problems.

A Bladder Problem

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At times, blood in a dog's urine (hematuria) may cause the urine to assume a brown, reddish tint. On top of dehydration, a potential cause of dark urine in a dog, is therefore a urinary tract infection, explains veterinarian Dr. Alleyne.

A urinary tract infection is particularly common in female dogs. With a shorter and wider urethra, a female dog is more predisposed compared to a male dog with a narrower and long urethra; however, male dogs occasionally get urinary tract infections as well.

Affected dogs often strain to urinate, urinate frequently and in small amounts, have accidents around the house , may lick their private areas and may drink more water and sometimes even vomit.

Other possible causes for blood in a dog's urine include presence of crystals in the urine or bladder stones, and in older dogs, a bladder tumor can be possible as well.

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A Liver Problem

Part of a dog's liver many tasks is to filter out old red blood cells, but if the dog's liver is not working as it should, bilirubin (the breakdown product of hemoglobin from old red blood cells) accumulates and it may cause urine to turn dark brown. Jaundice is the medical term used to depict the condition in which bile pigments accumulate in the dog's blood causing yellow mucous membranes. When these pigments are excreted in the dog's urine they cause it to appear dark.

Dogs with a liver problem often have yellow gums and may be vomiting. If a dog is showing dark urine and yellow gums, this can be suggestive of very levels of bilirubin in the blood which can stem from liver problems. Liver problems can include hepatitis, a gall bladder problem, an infection of the liver, or cancer, explains veterinarian Dr. Matt. 

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Presence of Anemia

When a dog presents with hemoglobin in the urine, this can be secondary to anemia. In dogs, immune-mediated hemolyticanemia can cause bursting of red blood cells inside the dog's blood vessels. The medical term for destruction of the red blood cells is hemolysis.

In some cases, eating raw onion, onion powder, or cooked onion, can cause anemia in dogs. What happens is that onions contain n-propyl disulfide, which is known for causing damage to a dog's red blood cells resulting in hemolysis, the medical term to depict destruction of red blood cells. Affected dogs become anemic, present hemoglobinuria and may vomit, appear weak, and pale, explains veterinarian Dr. Joey.

Possible Muscle Inflammation

At times, the urine discoloration may be due to an issue with the dog's muscles. An acute case of severe muscle inflammation, intense exercise or a traumatic injury, can be a cause. The dark urine in this case is due to break down of muscle, but this issue would be less likely to happen in a little house dog, explains veterinarian Dr. Gabby.

What happens exactly to cause the dog's urine to turn brown? Basically, when there is muscle damage as seen with crush trauma or strenuous exercise, the muscles excrete the protein myoglobin in the dog's urine. Rhabdomyolysis is the medical term for muscle injury causing the death of muscle fibers and its subsequent release of their contents into the dog's bloodstream. It's known for causing a tea-colored urine.

Rhabdomyolysis can also be caused at times by venom from a snake or insect bite or as a result of electrical shock or a severe burn. Left untreated, rhabdomyolysis may lead to renal failure.

At the Vet's Office

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Your vet will ask you several questions about your dog, his recent activity, what he is eating and whether there are any other changes you have noticed on top of the reddish brown urine.

Several tests may be run such as a complete blood count and a chemical profile. The vet may look for abnormal platelet counts, the number of liver enzymes and creatinine concentrations. A urinalysis can provide an insight on what is causing the urine to appear dark

X-rays and ultrasounds may be necessary to check for presence of bladder stones or possible signs of cancer.

Treatment varies based on the underlying cause. In a dog with a urinary tract infection, antibiotics may be prescribed. Dogs who are dehydrated may require IV fluids while dogs with anemia may require aggressive treatment meant to suppress the dog's immune systems and stop it from attacking the red blood cells.

As seen, there are several causes for reddish/brown urine in dogs. Because some of these causes can be serious and worsen quickly, it's important to see the vet as soon as possible.


Clinical Medicine of the Dog and Cat, Third Edition: edited by Michael Schaer, Frederic P. Gaschen

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