Bloody Urine (Hematuria/Hemoglobinuria/Myoglobinuria) in Horses

Key Takeaways

Brown or bloody urine in horses is urine that appears darker than usual as it exits the body.

• The urine stream may be very dark amber, brown, or red

• Brown or bloody urine is a symptom of urinary tract bleeding, breakdown of red blood cells, or muscle damage in the horse’s body

• Causes include bladder stones, toxicoses, “tying up”, tumors, and infections

• Brown or bloody urine requires immediate veterinary attention

• Diagnostic tools include physical examination, blood work, urinalysis, urethral endoscopy, rectal palpation, and ultrasound

• Treatment and prognosis depend on underlying cause

A Closer Look: What is Bloody Urine in Horses?

Bloody or brown urine indicates an issue in the urinary tract, including the kidneys, ureters, bladder and urethra. The brown or reddish tint in the urine can be caused by injury to the tissue inside the tract causing bleeding, the breakdown of red blood cells in the body, or the breakdown of muscle tissue. These conditions are called hematuria, hemoglobinuria, and myoglobinuria respectively. Each of these conditions results in blood or red pigments passing into the urine stream, changing the color of the urine.

Possible Causes

Causes of bloody or brown urine include:

• Urolithiasis (bladder stones) • Urinary tract tumors or cancer • Urinary tract infections • Kidney failure • Exercise-associated hematuria

• Neonatal Isoerythrolysis • Toxicoses, including Red Maple Toxicosis • Liver disease

• Muscle disorders such as Recurrent Exertional Rhabdomyolysis (“tying up”)

Risk Factors

Bloody or brown urine is uncommon in horses. Horses with bloody or brown urine require immediate veterinary attention. If the horse is a newborn foal, or if the horse has pale gums, emergency veterinary attention is required.

In general, reddish brown urine is considered to be the most severe form of this symptom, as it is typically associated with breakdown of red blood cells. However, accurately determining the color of urine is extremely difficult, and proper assessment requires specialized diagnostic tests. Horses with brown or red urine require immediate veterinary attention to determine the underlying cause.

Testing and Diagnosis

Veterinarian care is required for horses with brown or bloody urine. Diagnostic tools include:

• Physical examination • Blood tests • Urinalysis • Urethral endoscopy • Rectal palpation  • Ultrasound

• Biopsy of muscle or urinary tract tissue

Depending on diagnosis, treatments include:

• Surgery • Blood transfusion • IV fluid therapy • Exercise changes

Similar symptoms

Extreme changes to the color of urine as it leaves the body are cause for concern. Changes to the color of urine once it is outside the body (on the ground, in the snow) are not cause for concern since chemical compounds in the urine may oxidize once they are in contact with the air, turning the urine brown or red. 

Vulvar hemorrhage in pregnant mares can resemble hematuria.

Associated Symptoms

Depending on the underlying cause of bloody or brown urine, associated symptoms include:

• Difficulty urinating • Frequent urination • Dropped penis in males • Yellow gums • Pale or brown gums • Poor appetite

• Muscle twitching • Reluctance to move • Stiff gait

• Signs of colic including biting or kicking at flanks, rolling, poor appetite, small dry defecation, and changes in drinking

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