One of the more common issues we see with our pets is blood in the urine. This is often accompanied by other clinical signs like straining, going more often and discomfort. The first thing most people think of is a urinary tract infection, or UTI. While we can see these somewhat commonly in our pets, it is not the only reason for bloody urine.
Urinary tract infections are more common among female animals. This is because the urethra is short and wide, making it easier for bacteria to move their way up the urinary tract. Males have a long and narrow urethra so uncommonly have ascending infections. If a male patient has a urinary tract infection, typically they have another disorder that predisposed them like diabetes, a prostatic infection or other metabolic diseases. If you see blood in your pet’s urine, your veterinarian will often advise you to bring in a urine sample. If it is a male, then they will often also recommend an examination. A urinalysis, or urine test, can give us a lot of information. It can help diagnose infection or rule it out.
Sometimes a urine sample will appear to be bloody with the naked eye but isn’t. In certain species like rabbits, guinea pigs and rodents, we can see pigment in the urine called porphyrin. This is normal in these species and heavily influenced by diet. Cats and dogs generally do not have urine containing pigments but can with certain medical conditions like liver disease and muscle damage.
Bladder stones and urine crystals are another common reason for bloody urine. There are many different reasons for bladder stones and urinary crystals including genetics, diet, and infections. Your veterinarian may recommend either a radiograph or an ultrasound of the bladder to help rule out stones as a cause, especially in cases with reoccurring symptoms.
Unfortunately, we can also see bladder masses causing blood in the urine. Some of these can be benign, like polyps, but many are cancerous. Imaging can help us visualize the bladder wall to make sure there are not any abnormalities. There is also a specialized urine test called a CADET-BRAF that can help diagnose malignant bladder tumors like transitional cell carcinoma. Sometimes masses in the spleen, whether benign or malignant, can also cause blood in the urine.
This is not an exhaustive list of what can cause blood in the urine. Because there are so many different reasons, we often do not just prescribe antibiotics. While infection is a common reason, it is not the only reason. As veterinarians, we are trying our best to do what’s best for our patients and use antibiotics only when needed. Unfortunately, antibiotic resistance is more common among animals and people than we would like, so proving an infection before prescribing is important.