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ISU Student Experience

Urinary Obstruction in Cats: An Emergency Condition in our Feline Friends

Written by: Caitlin Peterson, 3rd year veterinary student • 2019 Scholar

Presentation and Physical Exam

Toby is an 11-year-old neutered male domestic short hair cat. He was brought in to IVS due to concerns about his urination habits. He was straining while attempting to urinate and urinating outside of the litterbox.

Upon palpation of his abdomen, his bladder was very large, tense, and painful. The bladder was about the size of an orange. There were no other significant findings during his physical exam.

Diagnostic Testing

To confirm a diagnosis, samples of Toby’s blood and urine were collected for analysis.


  • Evaluation of the blood is an important tool for veterinarians and the results can reveal a lot about the status of a patient including organ function.
  • Cell morphology and count were within normal limits.
  • Hyperglycemia (high blood glucose)
    • Toby’s blood glucose was very mildly elevated, which is a common finding in cats that are excited or stressed. This is known as “physiological hyperglycemia” and occurs due to the increased release of the stress hormone cortisol.
  • Elevated BUN and creatinine
    • BUN (blood urea nitrogen) is the main form of nitrogenous waste in mammals. It is produced in the liver, normally filtered from the blood in the kidneys, and then eliminated from the body via the urine.
    • Creatinine is a waste product of skeletal muscle. It is also filtered in the kidneys and eliminated in the urine.
    • An increase in both BUN and creatinine is a condition known as azotemia. The presence of azotemia is indicative of dehydration, renal dysfunction, or blockage. Veterinarians determine the cause with the patient’s history and physical exam findings. In Toby’s case, his inability to void his bladder caused the azotemia.
  • Slightly elevated globulins
    • Globulins are proteins found in the blood. Immunoglobulins (antibodies) are a type of globulin. An elevated number may be seen in cases of inflammation or infection.


  • Evaluation of the urine (urinalysis) is useful for determining possible causes of urine blockage and to check the health of the bladder.
  • Hematuria
    • Presence of red blood cells in the urine. This may be seen in cases of inflammation, as in Toby’s case.  
  • Pyuria
    • Presence of white blood cells. Often indicative of a urinary tract infection.
  • Bactiuria
  • Presence of bacteria in the urine. Bacteria in the urine is the cause of Toby’s urinary tract infection.
  • pH 7.0
    • A measure of the acidity of the urine. Carnivores such as cats typically have more acidic urine. Urine pH of a healthy cat is around 6.0. Toby’s was more alkaline, which could be due to byproducts of the bacteria in his urinary tract.
  • Urine specific gravity 1.033
    • Urine specific gravity is a measurement of the concentration of the urine and is used to determine function of the kidneys. In Toby’s case it tells us that his kidneys are working to properly concentrate the urine.


Toby was diagnosed with a urethral obstruction and a urinary tract infection. Blockage of a cat’s urethra is commonly referred to as a “blocked cat” or a “blocked tom,” although the condition is not restricted only to intact males. This blockage can be caused by stones or crystals in the bladder or urethra, a mucus plug, inflammation, or a mass. There are also other factors that can contribute to the condition, including stress, lack of water, diet, and infectious agents. Symptoms of the condition include frequent urination, straining to urinate, inappropriate urination (urination outside of the litter box), restlessness, crying while urinating, and may progress to lethargy and inappetence.

The body relies on the kidneys to regulate fluid levels and eliminate wastes via the urine. When a cat is unable to urinate the wastes build up in the body. A complete obstruction is an emergency condition and can lead to death within days without intervention. Luckily Toby’s blockage was noted early in the disease process. He had elevated BUN and creatinine, but his other values were within normal limits.

Treatment Plan

The first step of Toby’s care was to reduce the blockage in his urethra and put a urinary catheter in place. The urinary catheter remained in place for 48 hours and his urine output, including volume and appearance, was monitored. The BUN and creatinine values were rechecked 24 and 48 hours after the initial lab work to ensure proper kidney function and reduction of metabolites.

During this time Toby also had an intravenous catheter in place. He was given Normosol-R, a fluid solution containing balanced electrolytes. The fluids increased Toby’s intravascular fluid volume, which increased blood flow to the kidneys. As a result, the filtration rate in the kidneys increased and the BUN and creatinine were flushed from his system more rapidly.

Toby also received medications to help manage his condition:

  • Prazosin is an alpha-1 adrenergic blocker. It reduces sympathetic tone and decreases the resistance in the urethral smooth muscle. This helps to reduce irritation that the catheter causes and may also help reduce future reoccurrence.
  • Unasyn, an antibiotic, was given to treat Toby’s urinary tract infection.
  • Buprenorphine was given for pain relief.

After 48 hours, Toby’s renal values (BUN and creatinine) were down in the normal range and he seemed to be feeling great. His urinary catheter was removed and after he urinated on his own with no complications he was able to go home.


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