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Also Known As

Bladder infection


Cystitis is an inflammation of the urinary bladder resulting typically either from an ascending infection coming from the exterior of the body by way of the urethra or an infection descending from the kidney and renal pelvis. Difficulty in passing urine is often the first indication of cystitis.

Cystitis often occurs in relationship to other physical conditions. Tumors, neurological diseases impairing the function of the bladder, calculi in the bladder or urinary retention may lead to cystitis.

Horses pastured on sudangrass, sorghum or sorghum-sudan hybrid grass may also develop equine cystitis. Since there is no way to predict which horses might be susceptible to the disease, horses should not be allowed access to pastures with these grass species.

Although the bladder is strongly resistant to infection because of the cleansing flow of urine which dilutes and flushes bacteria, once an infection is established, it is difficult to cure. Bacterial cystitis is usually secondary to urine retention caused by paresis or paralysis of the bladder. Vaginitis and prolonged catheterization can also lead to this condition. .

In male horses, calculi is a common cause of cystitis, and in mares, vaginal infection often leads to this condition, although calculi in mares may become very large before symptoms appear. .


  • Dribbling urine that may cause skin scalding
  • Straining to urinate
  • Discolored or bloody urine
  • Positive bacterial culture
  • Mild recurrent colic
  • Loss of condition and coordination especially in hind legs
  • Sitting on hindquarters like a dog
  • Abortion in mares


Cystitis is caused by infection resulting in inflammation of the bladder. Often it is not an isolated infection, but is a result of other physical conditions such as tumors, neurological diseases, development of calculi, or submucosal cysts. Diet, water intake and loss, excessive sweating or diarrhea can precipitate the development of calculi.

Pasturing horses on sudangrass, sorghum or sorghum-sudan hybrid grass causes some horses to develop cystitis. Since there is no way to predict which horses will be susceptible to development of this infection as a result of grazing, horses should not be allowed access to these kinds of pastures.


Although there is no fool-proof way to prevent cystitis, the environment, diet, and on-going attention to the physical condition of each horse can help owners and handlers to catch the infection in its earliest stages to ensure proper treatment.

Given the fact that certain grasses can cause cystitis, horses should not be pastured in pastures where sudangrass, sorghum of sorghum-sudan hybrid grasses are grown, nor should they be fed cuttings from such pastures.


If calculi is the cause of the cystitis, surgery may be necessary. In other cases, correction of the underlying problem and antimicrobial therapy are indicated. An ultrasound examination can help determine the location and extent of bladder wall thickening.

Prolonged treatment regimes are essential since relapses are common because of dormant bacteria in the bladder wall. Bacterial cultures of urine and antimicrobial sensitive testing of cultured bacteria will help the veterinarian determine a course of treatment. Penicillin and trimethoprimsulfa are often used to treat the affected horse with good results.

In any case of cystitis, a veterinarian's diagnosis and prescription for treatment are crucial to a satisfactory outcome for the horse.

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EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.