Blood Clots in Dog Urine: Causes and Next Steps

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-03

Blood clots in urine in dogs mean something in the urinary tract is bleeding enough for blood to clump before it leaves the body. Clots can come from the bladder, the urethra, the kidneys, or the prostate, and the cause ranges from a treatable infection to a tumor. Some causes are emergencies, so the clot itself matters less than how your dog looks and acts right now.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

• A clot means active or recent bleeding somewhere in the urinary tract, and it needs veterinary evaluation, not watchful waiting.
• The most common causes are urinary tract infections, bladder stones, and inflammation of the bladder lining.
• Blood clots are not normal at any age, and they are not caused by heat cycles alone.
• If your dog is straining with nothing coming out, crying, vomiting, or collapsing, treat it as an emergency and go now.
• Collect a fresh urine sample in a clean container if you can do it safely, but never delay a trip to the vet to get one.

What Blood Clots in Dog Urine Look Like

Normal urine versus bloody urine

Normal dog urine ranges from pale yellow to amber. It should be clear or nearly clear, with no visible solid material. A few drops of blood from a heat cycle or a mild irritation can tint urine pink or red, but that is different from a clot.

A clot is a jelly-like or gelatinous blob. It may look like a small piece of liver, a dark red string, or a clump that settles at the bottom of the puddle. Clots can be tiny, or large enough to be obvious at a glance. Some owners describe dog pee with blood clot material as looking like raspberry jam mixed into the urine.

Why clots form

Blood normally clots when it is exposed to damaged tissue. When a blood vessel in the bladder wall, urethra, or kidney is eroded or torn, blood leaks into the urine. If the bleeding is fast enough, the blood has time to clot before it is flushed out. That is why clots tend to point toward heavier or more active bleeding than a simple pink tinge.

A thrombus is a blood clot that can form when blood flow is restricted, when a vessel lining is damaged, or when a condition makes a dog produce clots excessively [1]. In the urinary tract, the same principles apply on a smaller scale, and a clot that forms in the bladder or urethra can partially block the flow of urine.

What is not normal

Blood clots are never a normal finding. A single clot does not tell you how serious the cause is, but it does tell you that bleeding happened. Do not assume a clot is harmless because your dog seems fine afterward.

Causes of Blood Clots in Urine in Dogs

Many conditions can produce hematuria with clots in dogs. The table below groups the main ones and what usually points toward each.

Urinary tract infections

UTIs are one of the most common reasons for blood in dog urine. Bacteria inflame the bladder lining, and that inflamed surface bleeds easily. A study of working dogs with cystitis found hematuria and proteinuria on urinalysis, along with higher white blood cell and platelet counts [2]. If your dog has a UTI, the bleeding usually improves quickly once the right antibiotic is started. For a deeper look at this pattern, see Why Is My Dog having bloody urine? Cystitis Bladder Stones and UTI Guide.

Bladder stones

Stones scrape the bladder wall and the urethra as they move. Dogs with urolithiasis in one study showed abdominal pain, difficult urination, hematuria, and urinary retention, and their urine contained calcium oxalate or struvite crystals [2]. Stones can also cause clots directly by injuring the lining. A stone that lodges in the urethra is a life-threatening blockage, especially in male dogs, because the urethra is narrow.

Inflammation and cystitis

Cystitis means inflammation of the bladder. It can happen with infection, with stones, or on its own. The inflamed lining leaks blood, and clots can form if the bleeding is brisk. Some dogs have crystalluria without stones, which still irritates the bladder. In dogs with a liver condition called primary portal vein hypoplasia, ammonium biurate crystals and uroliths were found in a portion of cases, and some of those dogs had lower urinary tract signs [3].

Tumors

Bladder tumors, including urothelial carcinoma, often cause persistent hematuria. One case report described a dog with severe hematuria that was later confirmed to have urothelial carcinoma in the bladder [4]. Another report described a dog with hematuria, frequent urination, and a suspected trigonal tumor along with extensive stones throughout the urinary tract [5]. Tumors are more common in middle-aged and older dogs, and the bleeding tends to come and go.

Prostate problems

In male dogs, an enlarged or infected prostate can bleed into the urethra. You may see blood at the start of urination or drops of blood after urination. Prostate disease can also make a dog strain to poop.

Kidney disease and other internal causes

The kidneys can bleed with infection, stones, or tumors. Chronic kidney disease is staged from I to IV based on lab work, physical exam, and signs, and by Stage III or IV many dogs feel sick [6]. Bleeding disorders and clotting problems are less common causes of urinary clots, but they matter because they can affect the whole body. A thrombus can form when blood flow is restricted or a vessel lining is damaged, and some clots can break off and travel [1].

Age and cognitive changes

Older dogs can have hematuria along with other urinary changes. In a study of aging dogs, 14 of 231 urine samples showed hematuria, and urine specific gravity decreased with age [7]. Soiling in an older dog is not always a behavior problem. It can be a medical sign.

Red Flags That Make This an Emergency

Go to an emergency clinic now if you see any of these:

• Your dog is straining to urinate and only drops or nothing comes out.
• Your dog is crying, pacing, or licking the belly and cannot settle.
• The belly looks bloated or feels hard.
• Your dog is vomiting, weak, collapsing, or breathing fast.
• The gums are pale, white, or blue.
• There is a large amount of blood or many clots, not just a tinge.
• Your dog cannot walk or seems painful in the back or hind legs.
• You know or suspect your dog ate a toxin, such as rodent bait.

A complete blockage stops urine from leaving the body. That is fatal within a day or two if it is not relieved. Do not wait to see if it passes.

Safe Things You Can Do at Home While Waiting

Home care cannot treat the cause, but it can keep your dog safer until you reach the vet.

• Offer water. Do not restrict fluids unless your vet tells you to.
• Keep your dog leashed and calm. Running and jumping can make bleeding worse.
• Do not give human pain relievers. Many are toxic to dogs, and the dose depends on your dog's weight and health. Your veterinarian calculates any medication dose for your pet.
• Do not give antibiotics left over from another pet or another illness.
• Collect a urine sample if you can. A clean, shallow container works. Catch the urine mid-stream if possible. Label it with the time.
• Take a photo of the clot or the bloody urine. It helps your vet judge how much bleeding occurred.
• Note when the problem started, how often your dog urinates, and whether your dog can pass a normal stream.
• If your dog has a known bleeding disorder or takes a blood thinner, call the vet before you do anything else.

If your dog stops urinating, that is not a wait-and-see problem. Call the clinic and say your dog may be blocked.

What Your Veterinarian Will Check and Test

History and physical exam

Your vet will ask about the timeline, the amount of blood, straining, accidents, water intake, diet, and any medications. The exam includes feeling the belly, checking the bladder size, checking the gums, and in male dogs, checking the prostate.

Urinalysis

This is the core test. It checks urine concentration, pH, protein, blood, crystals, and cells. It also looks for bacteria and white blood cells that point to infection. A urine culture may follow to identify the exact bacteria and the right antibiotic. Home test strips can give you a rough idea, but they cannot confirm an infection. For more on that, see Veterinary Urinalysis Strips at Home: Leukocytes, Protein, pH, Microalbuminuria, and Vet Confirmation.

Blood work

A complete blood count and chemistry panel show whether your dog is anemic from blood loss, whether the kidneys and liver are working well, and whether there are signs of infection or inflammation. Dogs with urolithiasis in one study had lower red blood cell counts and hemoglobin along with higher white blood cells, neutrophils, and platelets [2].

Imaging

X-rays and ultrasound are used to look for stones, tumors, and bladder wall changes. Ultrasound can also check the kidneys and prostate. Bladder wall thickening is common in dogs without urinary tract disease and can reflect normal mucosal folding, so the finding has to be read in context [8]. That is one reason imaging results are interpreted along with the whole picture, not alone.

Other tests

If a tumor is suspected, your vet may recommend a biopsy or a specialized urine test. If a bleeding disorder is suspected, clotting tests may be needed. In some cases, a contrast study or CT scan gives a clearer view of the urethra and bladder. A case report described a dog with an obstruction from a mass and a narrowed urethra that required advanced imaging to sort out [9].

Prevention and Monitoring

You cannot prevent every cause of blood clots in urine, but you can lower the risk of some.

• Treat UTIs fully. Finish the prescribed course and follow up if your vet wants a repeat urine test.
• Manage stones. If your dog has had stones, your vet may recommend a specific diet and regular imaging to catch new ones early.
• Keep water available. Good hydration supports urine flow and can reduce crystal formation.
• Watch older dogs closely. Persistent blood in the urine in a middle-aged or older dog deserves imaging, not just antibiotics.
• Track patterns. Note how often your dog urinates, the color, and any straining. A written log helps your vet spot trends.
• Keep routine visits. Early kidney disease often has no signs, and Stage I is when treatment has the best chance of success [6].

If you see blood again after treatment, call your vet. Recurring blood is a reason to look deeper. For related bleeding signs, see Dog Blood in Urine: Causes and Emergency Steps and Blood in dog stool causes urgency and veterinary evaluation.

Limitations and When to Contact a Veterinarian

This article cannot tell you what is causing your dog's bleeding. Only an exam and tests can do that. Individual cases need a veterinarian.

Call your vet the same day if you see clots but your dog is eating, drinking, and acting mostly normal. Call immediately, day or night, if your dog is straining with little or no urine, vomiting, weak, or in pain. A dog that cannot pass urine needs emergency care now. A dog with a few clots and mild symptoms still needs a same-day or next-day appointment, because the cause could be a stone, an infection, or a tumor. If you are unsure, call the clinic and describe what you saw. They can tell you whether to come in right away.

Frequently Asked Questions

What does a blood clot in dog urine look like?

It looks like a jelly-like blob, a dark red string, or a clump that settles in the puddle. It may be small or large enough to see clearly. Some clots look like bits of tissue, which is why a photo helps your vet.

Can a urinary tract infection cause clots in a dog's urine?

Yes. A UTI inflames the bladder lining, and that surface can bleed enough to form clots. Infection is one of the most common causes of blood in dog urine. Treatment usually clears the bleeding once the right antibiotic is chosen.

Is blood in dog urine always an emergency?

No, but it always needs a vet visit. Mild blood with a happy, drinking, urinating dog can often wait until the next appointment. Blood with straining, no urine output, vomiting, or weakness is an emergency.

Can bladder stones cause blood clots in urine?

Yes. Stones scrape the bladder and urethra, which causes bleeding and sometimes clots. A stone stuck in the urethra can block urine flow completely. That is a life-threatening problem, especially in male dogs.

Should I wait to see if the blood clears up on its own?

No. Blood in urine can come from a minor problem or a serious one, and the amount of blood does not tell you which. Waiting risks a blockage, worsening infection, or a tumor growing. Call your vet and get an exam.

Related Articles

• Dog Blood in Urine: Causes and Emergency Steps
• Why Is My Dog having bloody urine? Cystitis Bladder Stones and UTI Guide
• Blood in dog stool causes urgency and veterinary evaluation
• Veterinary Urinalysis Strips at Home: Leukocytes, Protein, pH, Microalbuminuria, and Vet Confirmation
• Dog Pooping Blood but Acting Normal: What to Do
• Signs Of Uti In Dogs
• Red Dog Urine: Causes, Blood in Pee, and When to Call the Vet
• Jelly-Like Blood in Dog Urine: What It Means
• What Causes Bladder and Kidney Stones in Dogs?

References

1. Blood Clots and Aneurysms in Dogs - Dog Owners. Merck Veterinary Manual.
2. Comprehensive diagnostic evaluation of urolithiasis and cystitis in K9 dogs in Iraq: Clinical, laboratory, and imaging correlates. Open veterinary journal, 2025.
3. Urolithiasis and crystalluria in dogs with primary portal vein hypoplasia: a retrospective study (2010-2023). The Journal of small animal practice, 2026.
4. Corneal stromal metastasis of urothelial carcinoma in a dog. Research in veterinary science, 2026.
5. Case Report of Urethral Stenting in a Dog with Multifactorial Lower Urinary Tract Obstruction Associated with Suspected Transitional Cell Carcinoma and Severe Cystolithiasis. Veterinary sciences, 2026.
6. Noninfectious Diseases of the Urinary System in Dogs - Dog Owners. Merck Veterinary Manual.
7. The relationship between urinalysis abnormalities, soiling behavior, and cognitive decline in aging dogs. Journal of veterinary internal medicine, 2026.
8. Prevalence and characteristics of bladder wall thickening in dogs without lower urinary tract disease: an ultrasonographic study. Frontiers in veterinary science, 2025.
9. Hydrocolpos in a mixed-breed dog: a case report. Frontiers in veterinary science, 2026.

Further Reading

• The Urinary System of Dogs - Dog Owners (Merck Veterinary Manual)
• American Veterinary Medical Association: First Aid Tips for Pet Owners
• Merck Veterinary Manual: Dog Owners