Summary
Urinary obstruction, also known as urethral obstruction, urinary blockage, or being "blocked," is the inability of a pet to urinate.
The bladder is the part of the urinary tract that stores urine. When your pet is ready to urinate, the urine moves from the bladder into a tube-like structure called the urethra, then out of the body through the urethral opening. A blockage can occur at the bladder opening that leads to the urethra or within the urethra itself. Urinary obstruction is much more common in cats, but it can also happen in dogs.
Things that cause urinary blockage include accumulation of mucus (mucus plug) within the urethra, bladder stones (especially if they have moved from the bladder to the urethra), urinary tract cancer, severe urinary tract infections, or a stricture/scarred down region of the urethra.
Urethral spasms, swelling, and pain, which are seen with feline lower urinary tract disease (also known as idiopathic cystitis) can also cause urinary blockage to the point that a cat can't pee.
Symptoms and Identification
Pets with urinary obstruction will stand still in an attempt to urinate, but no pee will be produced. They may try to urinate numerous times over a short period, or they may stand still for a long time with no success at peeing. The inability to urinate will become very painful, so most animals will act painful or aggressive if their belly is touched.
Those who have gone more than 24 hours may become very sick. This is because urine is the body's toxic waste that has been filtered out by the kidneys. A dog or cat not peeing for more than one day is usually a life-threatening situation and needs to be handled as an emergency. Symptoms include:
Severe Belly Pain
Laying Around and Not Responding to You
No Appetite
Breathing Heavily
Possibly Cool Arms and Legs
Not peeing for more than 24 hours can lead to the bladder rupturing from being too full, causing urine to leak into the abdomen. This can cause the pet to go into shock - they can even die within a short period of time.
To identify urinary obstruction, your vet will assess your pet and do a thorough examination. They will feel the belly, and if the pet isn't too painful or aggressive, may be able to feel a very large, painful bladder.
Sedation and pain medication are often needed immediately to finish the exam and try to express the bladder to see if the pet can urinate at all. X-rays may be performed to see if bladder stones are part of the problem. Blood tests, such as a complete blood count (CBC) and chemistry panel will be performed to see if their body is experiencing toxicity associated with the inability to pee (e.g. elevated kidney values like BUN and creatinine, abnormal electrolyte levels).
Some of the cat or dog's urine may also be examined to see if the cause of the blockage can be determined (e.g. infection, bladder stone crystals).
Affected Breeds
Male cats are more likely to experience urinary blockage than females, partially because males have a longer urethra. Overweight cats and cats fed only dry food are possibly at higher risk than others. The average age of a blocked cat is 4.3 years old, and all breeds are at risk.
Urinary blockage is uncommon in dogs, and no breeds or age of dog have been reported to be at a high risk. Males are more likely to be affected than females.
Treatment
Urinary blockage is an emergency, so treatment is often started while the pet is still sedated. Your veterinarian will try to pass a urinary catheter, which is a lubricated sterile tube, inside the pet's urethra to try to remove or move past the blockage and release the urine from the bladder.
If a large amount of urine has been blocked inside the bladder for an extended period of time, the release of this urine can lead to an extreme loss of water and electrolytes (e.g. salt), causing a phenomenon called post-obstructive diuresis. Because of this, pets are often placed on a high rate of intravenous (IV) fluids just before or once their urine is released.
For pets in which a cancerous tumor or bladder stone is causing the blockage, surgery is needed. Your veterinarian may be able to pass a urinary catheter to allow your pet to urinate, but this is not always the case and an emergency surgery may be needed.
Occasionally, a blockage is caught early enough that the catheter can be removed immediately after the blockage is fixed and urine is released. This is usually only effective for mild urethral spasms or urinary tract infections, and even then, re-blockage may happen.
Most of the time, the urinary catheter must be left in place for several days while the cat's urethra and bladder heal. During this time, IV fluids, pain medications, medication for urethral spasms and swelling, and sometimes antibiotics will be administered. Blood work is repeated often to monitor for post-obstructive diuresis and toxic changes.
Once your pet is ready to be discharged from the hospital, they will likely be sent home on pain medications, medication for spasms, and possibly antibiotics and a prescription diet tailored to the urinary tract. The diet may be necessary for the remainder of the pet's life. Switching to canned food or increasing their water intake will also likely be recommended to help continually flush the bladder and avoid re-blockage.
Veterinary Cost
Diagnose Cost Ranges from $100-750
Treatment with Hospitalization Ranges from $150-450/ Day (depending on blood work, medication, and monitoring needs)
Surgery Ranges from $750-1,500
The remainder of the cost depends on the pet's severity of illness and how he or she recovers.
Prevention
Prescription diets for bladder health can prevent a pet from re-obstructing. Most veterinarians do not recommend starting such a diet if your pet has never shown issues urinating. Monitor your pet closely for any signs of straining or struggling to urinate and take them in as soon as you can to avoid a full obstruction.
References
Bartges JW: Urethral Diseases. Eds. Ettinger SJ, Feldman EC, Cote E. Textbook of Veterinary Internal Medicine. Elsevier, St. Louis MO 2017 pp. 2020-2026.
Segev G, Livne H, Ranen E, et al: Urethral obstruction in cats: predisposing factors, clinical, clinicopathological characteristics and prognosis. J Feline Med Surg 2011 Vol 13 (2) pp. 101-103.
Eisenberg BW, Waldrop JE, Allen SE, et al: Evaluation of risk factors associated with recurrent obstruction in cats treated medically for urethral obstruction. J Am Vet Med Assoc 2013 Vol 243 (8) pp. 1140-1146.
Stiller AT, Lulich JP, Furrow E: Urethral plugs in dogs. J Vet Intern Med 2014 Vol 28 (2) pp. 324-330
Fults M, Her LV: Retrospective evaluation of presenting temperature of urethral obstructed male cats and the association with severity of azotemia and length of hospitalization: 243 cats (2006-2009). J Vet Emerg Crit Carew 2012 Vol 22 (3) pp. 347-354.
Francis BJ, Wells RJ, Rao S, et al: Retrospective study to characterize post-obstructive diuresis in cats with urethral obstruction. J Feline Med Surg 2010 Vol 12 (8) pp. 606-608.
Hetrick PF, Davidow EB: Initial treatment factors associated with feline urethral obstruction recurrence rate: 192 cases (2004-2010). J Am Vet Med Assoc 2013 Vol 243 (4) pp. 512-519.
Ruda L, Heiene R: Short- and long-term outcome after perineal urethrostomy in 86 cats with feline lower urinary tract disease. J Small Anim Pract 2012 Vol 53 (12) pp. 693-698.