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Bacterial cystitis in dogs

pet-health

Cystitis bacterial infection in dogs is the most common disease of the canine urinary system, caused by the growth of bacteria that invade the bladder. It is particularly common in females, and can be difficult to treat as it often recurs. Let's take a closer look at bacterial cystitis, which can sometimes be a sign of urolithiasis or tumors.

The functions and roles of the urinary bladder

The bladder is an organ that temporarily holds the urine produced by the kidneys before it is expelled. The inside of the bladder is essentially sterile, and several methods are used to prevent bacterial infection. The mucosal surface of the bladder contains a protein called glycosaminoglycan, which prevents bacteria from adhering to it. Urine itself is also thicker than body fluid, and its osmotic pressure inhibits bacterial growth. The urine is released vigorously to flush out bacteria in the urethra and bladder.

Males with a longer urethra than females are less prone to bacterial cystitis.

Causes of bacterial cystitis in dogs

Bacterial cystitis is caused by an infection with bacteria such as E. coli, an intestinal bacterium. The bladder has basically an immune system against bacteria, but when its function is compromised due to the following factors, bacteria that enter through the urethra multiply and cause various symptoms of cystitis. In particular, females, whose urethra is shorter than that of males, are more susceptible to cystitis because of the proximity of the vulva to the anus and the easy entry of bacteria, including in the sitting posture. In addition, there are many cases of refractory cystitis that recurs repeatedly even after treatment.

  • Lack of water
  • When your dog drinks not enough water, the production of urine will diminish, and less urine means more time in the bladder. This gives the bacteria time to multiply. Also, if your dog only urinates during walks, less frequent walks will result in less urination, and the same will result in more time spent in the bladder. Of course, this is not the only factor that can lead to bacterial cystitis, but it is a contributing factor to its development. Increased activity has been shown to increase the frequency of urination, so make sure your dogs drinks plenty of water and exercises moderately to create an environment that will increase urination frequency.

  • Diseases that cause watery urine
  • The endocrine disorders such as hyperthyroidism, diabetes, and chronic kidney disease prevent urine make urine thick. Thick urine inhibits bacterial growth, but watery urine makes it easier for bacteria to multiply. A weakened immune system in these diseases is also thought to be a factor in bacterial cystitis.

  • Stone or tumour formation
  • If there is a mass such as a urinary stone or tumour in the bladder, it may form a wall when the bladder contracts and urinates, making it impossible to excrete all the urine. Urine that remains in the bladder becomes a breeding ground for bacterial growth. Stones and tumours can also break down the mucous membrane of the bladder, making it easier for bacteria to adhere and cause infection. With some stones, the stones themselves can become a nest for bacteria.

  • Inflammation of the vulva
  • In females, the vulva is covered with hair and skin, and may become constantly moistened by adherent urine, causing urine scald. This destroys the indigenous flora of the skin and becomes a breeding ground for bacterial infections that can cause cystitis. Sometimes vaginitis occurs, which is also a source of bacterial infection. If the pubic area is covered with skin, it needs to be shaved and cleaned frequently.

  • Insertion of urethral catheter
  • A urethral catheter may be inserted for urine collection and testing, which may cause bacterial invasion. It is important to understand that no matter how careful you are, infection can still occur. Depending on the situation, spontaneous urination or cystocentesis is not a cause of infection. ※Cystocentesis: A method of collecting urine from the bladder by inserting a needle into the abdomen.

  • Congenital anomalies
  • A congenital abnormality in which the ureter, which connected the bladder to the mother's body as a fetus, remains partially intact after birth is called “ureteral remnant. If the ureter remains at the tip of the bladder, a condition called “bladder diverticulum” occurs. When urine accumulates in this diverticulum, bacteria can easily multiply.

Symptoms of bacterial cystitis in dogs

Even if your pet has bacterial cystitis, he/she may not show any symptoms. Especially if he/she already has a disease such as diabetes or chronic kidney disease, there is a risk that the bacteria can infect the kidneys. If your dog has symptoms, he needs to be examined and treated promptly. It is recommended that a urine test be added to a physical examination or as advised by your vet. In addition, when symptoms appear, the following conditions can occur:

  • Bloody urine
  • Inflammation of the bladder and urinary tract leads to urine with blood in it. It is brown to red in color and you should consult your veterinarian as soon as you find it. It's also important to monitor urination, frequency, color and smell.

  • Painful dysuria Painful contraction of the bladder, and urinating only a small amount at a time.


  • Dysuria (inability to urinate)
  • Chronic cystitis can cause difficulty in contraction of bladder, resulting in dysuria. If bacterial infection persists, it can lead to urolithiasis, and your dog may not be able to urinate due to stone blockage.

  • Cloudy urine
  • In severe cases of bacterial infection, inflammatory cells turn into pus, resulting in cloudy white pyuria.

  • Urination in inappropriate places or incontinence
  • Frequent urination (urinating more often but less per urination)

How to diagnose bacterial cystitis in dogs

  • Urinalysis
  • If a bacterial cystitis is suspected, the first step is to diagnose the problem through a urinalysis, which can be used to check for abnormalities in the bladder. It is recommended to collect urine with a clean paper plate. If it takes more than 30 minutes to get the test done, so keep the urine refrigerated. If it is difficult for your dog to collect urine, ask for urine to be collected by cystocentesis (a method of collecting urine from the bladder by inserting a needle through the abdomen) instead of a catheter.

  • Ultrasonography: If stones are suspected or recurring, ultrasound imaging can be used to check the condition of the bladder in more detail than a urinalysis.

  • Bacterial culture test: If bacterial cystitis is confirmed, a bacterial culture test will be performed to determine what kind of bacteria is infecting the bladder in order to prescribe the most appropriate antibacterial drug.
  • How to prevent bacterial cystitis in dogs

    Cystitis itself is not a fatal disease, but it can become intractable with repeated recurrences and can trigger complications that can infect the kidneys.

    Especially for females who are prone to bacterial cystitis, it is essential to prevent and control the recurrence of the disease by the following methods on a daily basis.

    • Keep the vulva clean
    • When you take your dog out for a walk, clean the vulva after every urination and defecation to keep it clean. If you use a disinfectant, it will kill the indigenous bacteria, so tap water is fine. Wipe them with a clean towel. Shaving the pubic area can also be effective.

    • Make your dog drink plenty of water
    • It is essential to make sure your dog drinks enough water to promote urination. To ensure that your dog can consume water at any time, you can:
      ✔Increase the number of water dishes.
      ✔Change fresh water frequently.
      ✔Incorporate wet food.
      ✔Fluff dry food
      Increasing activity, such as taking more frequent walks, will increase the frequency of urination and expel bacteria from the bladder, thus preventing the growth of bacteria.

    • Take cranberry extract
    • Although cranberry juice is used as a folk remedy for cystitis in humans to inhibit the growth of bacteria, there is no proven efficacy of cranberry juice for dogs. However, there are reports that cranberry extract supplements have improved bacterial cystitis in dogs.

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