Witnessing your pet pee blood can be very concerning. There are several possible causes of hematuria (blood in urine), many of which would be treated differently. It is important to get your pet evaluated by your vet for a thorough work up to determine which treatment approach is most appropriate.
What Causes Bloody Urine in Dogs?
Let’s split up the differential list into two categories: local (bladder problems) and systemic (entire body problems).
Causes of bloody urine that just involve the bladder include severe cystitis, or inflammation of the bladder wall, and bladder cancer.
Systemic causes include trauma, bleeding disorders, or disease from other organs, namely the kidneys or prostate (males only).
Local Bladder Problems in Dogs
Urinary tract infections (UTIs) can be primarily bacterial, meaning there are no other underlying causes, but inflammation can also be caused by urinary stones, which often have secondary bacterial infections. Female dogs, like people, are more prone to developing primary bacterial UTIs due to anatomy. The entrance of the urethra (the tube that brings urine from the bladder to the outside world) is very close to the anus, which allows bacteria from feces to travel up the urethra and enter the bladder.
Male dogs almost never get simple bacterial UTIs; there is usually some underlying cause. One of the most common causes is urinary stones. Urinary stones themselves are very complex, so please see the articles specifically about them for more information. For the purpose of this article, urinary stones can rough up the bladder lining, causing inflammation and thus bleeding, but also act as a nidus or “hiding place” for bacteria. This means if the dog receives antibiotics, the bacteria can latch onto the stones, and the infection will not fully clear until the stones are taken care of.
Other underlying problems that cause secondary UTIs include Diabetes, Cushing’s Disease, prolonged steroid use, and anything else that may cause a compromised immune system. Either way if the inflammation is bad enough, the urine can turn red, brown and/or cloudy.
The most common type of bladder cancer is called Transitional Cell Carcinoma, which is seen mostly in older dogs. This is a malignant tumor of the lower urinary tract that can grow in single masses or clusters. It is most often found at the neck of the bladder. Not only can the mass itself bleed, but it too can act as a nidus for infection. Also, if it gets big enough, it can potentially cause a urinary obstruction, preventing the animal from urinating normally (causing straining, more irritation, and thus bloody urine). Luckily this and other bladder cancers are not common.
Systemic Bladder Problems in Dogs
Trauma is listed as a systemic cause because other organs are usually impacted by traumatic events—they don’t just target the bladder. Trauma such as being hit by a car, dog fights, or abuse can rupture blood vessels within the bladder lining, which can cause bloody urine. If the trauma is severe enough, it can even cause the bladder to rupture or break. This makes a very sick dog and there will be many other serious clinical signs in addition to the bloody urine.
Dogs also get bleeding disorders, which can make blood come out pretty much anywhere, including bruises on the skin, internal bleeding, and bloody urine. The most common toxic causes occur after the dog eats anti-coagulant rat poison (most commonly containing brodifacoum), a penny minted prior to 1983, which contains zinc, or garlic and onions.
Another bleeding disorder cause is immune mediated. This is when the body’s immune system attacks its own cells, either the red blood cells or the platelets that help with clotting. Bloody urine is not specific for bleeding or clotting issues, but can be a clue.
Disease of other organs in which come in contact with urine can also cause bloody urine. Kidney diseases such as infection, degeneration, or kidney stones can be a cause. Prostate diseases in male dogs, either infection or cancer, may also be a cause of bloody urine. In females, a severe vaginitis (inflammation of the vagina) may be a culprit.
At the Vet's Office
Your veterinarian will gather clues as to which cause is most likely. This includes signalment (age, sex, breed, etc.), clinical signs, duration, potential exposure to toxins or known traumatic events. A thorough physical exam will look for any other abnormalities to help determine if this is a local or systemic problem.
A urinalysis will likely be run to look for bacteria, crystals (which may indicate stones), inflammation, or cancer cells. The doctor may recommend running a blood panel too, which can help determine if other organs are involved. If stones or cancer are suspected, imaging may be recommended. This includes x-rays and/or ultrasound. Keep in mind not all stones show up on x-rays, so both tests may be necessary.
Other diagnostic tests that may be recommended depending on the case include urine culture and sensitivity, where the specific bacteria is isolated and the specific medications it is sensitive to are identified, urine protein:creatinine ratio (comparing loss of proteins in the urine to a kidney enzyme), or clotting times. If this is a recurring problem, more tests are usually indicated to get to the underlying cause.
You can see that there are several causes of bloody urine, and can imagine each one is treated differently. It is important to get your pet to the vet in a timely manner to determine the best diagnostic and treatment approach.
About the Author
Dr. Eric Weiner is a small animal veterinarian practicing in Orlando, Florida. He is a third generation veterinarian as both his father and grandfather are vets. Although he grew up following both of them around and wanted to be a veterinarian himself, he took a bit of a detour and attended Hofstra University originally as a music major.
Eventually realizing his true passion still lays within Veterinary Medicine, he switch majors and graduated in 2010 with a BA in biology and dual minors in biochemistry and music. Dr. Weiner attended Virginia-Maryland Regional College of Veterinary Medicine and graduated in 2015, concentrating in mixed animal medicine and surgery. During his clinical year, his favorite rotation was which ever he was currently on. He especially enjoyed spending time at the Penn Vet Working Dog Center, where he worked closely with search and rescue dogs, diabetic alert dogs, and even cancer detection dogs.
When Dr. Weiner is not working with animals, he enjoys riding his motorcycle and playing baseball. He is married to his high school sweetheart and they are enjoying their brand new baby girl. In addition, they live with their therapy dog Murphy, and two cats, Stella and Luna.