The color of urine is an important indicator of your dog’s health. Normal urine is typically transparent and yellow or amber. Any discoloration of the urine is abnormal and should be considered a warning sign in most cases.
When discoloration is caused by blood in the urine (a condition referred to as hematuria by veterinarians), the color of the urine may be red, brown, or even black, depending on the changes in the main blood pigment, hemoglobin. However, sometimes the presence of blood in your dog’s urine isn’t macroscopically detectable upon visual inspection. In this case, it can only be confirmed through microscopic examination of the urine sediment, which will reveal red blood cells.
When blood in the urine is immediately visible to the naked eye (macroscopic hematuria), the color of the urine varies depending on the amount of blood lost. A hemorrhage of just 1 ml of blood (approximately one-fifth of a teaspoon) is enough to make the condition visually detectable. In this case, the urine usually appears red, with varying tones. However, traces of blood in your dog’s urine can sometimes impart a color other than red. For example, if the urine is particularly acidic, it may appear dark brown. Dark brown can also be the color of urine with blood that has remained in the urinary tract for a prolonged period. This discoloration is caused by the oxidation of hemoglobin in the blood.
Causes for Blood in a Dog’s Urine
Before discussing the potential causes of blood in your dog’s urine, it’s important to note that urine can appear red or reddish-brown even in the absence of hematuria. For example, the red color of urine may sometimes result from the consumption of certain drugs (e.g., neoprontosil, rifampin, phenothiazines) or foods (e.g., blackberries, beets). It can also be caused by certain diseases that result in red urine without blood, such as porphyrias (which cause a winy red color due to an excess of pigments called porphyrins) and myoglobinuria (which gives the urine a reddish-brown color from muscle myoglobin caused by muscle damage).
This is why, if you suspect your dog has blood in its urine, it’s important to get a urine test as soon as possible to confirm the presence of blood and rule out other potential causes of red urine.
The presence of blood in your dog’s urine is not a disease in itself, but rather a symptom of various health conditions. Treatment depends on addressing the underlying cause. First, a differentiation must be made between hematuria originating from the urinary tract (kidneys, ureters, bladder, urethra) and hematuria caused by genital tract contamination (prostate, prepuce, vagina).
As for the first group, the most obvious cause of blood in your dog’s urine is trauma, which may result from blunt force (e.g., a car accident) or from traumatic diagnostic procedures (e.g., urine collection via catheter or cystocentesis, renal biopsy). Other common causes of hematuria from the urinary tract include urolithiasis (stones in the urine) and neoplasia or infections of the kidneys, bladder, and urinary passages.
Sometimes, blood in your dog’s urine can be caused by a systemic blood issue, such as coagulopathies—conditions that affect blood clotting (e.g., warfarin intoxication, low platelet count).
Hematuria from genital tract contamination is usually due to inflammatory, neoplastic, or traumatic lesions of the genital tract, or it may be associated with estrus in female dogs. In this case, it’s not a sign of illness but a natural physiological process.
For diagnosing the underlying cause, laboratory and diagnostic tests are important. Additionally, evaluating any associated symptoms is crucial, and the cooperation of the pet owner can be key. For example, if blood loss in the urine is accompanied by severe abdominal pain, this could indicate kidney or urethral stones. Similarly, if your dog has blood in its urine and shows difficulty urinating, this may suggest urethral obstruction due to prostatic disease or urethral stones.
As previously mentioned, there is no universal treatment for hematuria. Therapy must target the underlying cause. However, whenever you notice blood in your dog’s urine, it’s crucial to take your pet to the veterinarian as soon as possible. Some of the conditions mentioned (such as traumatic injury, bladder rupture, or urethral obstruction) can be life-threatening and require prompt treatment.
