The "Blocked" Cat

Feline Urinary Obstruction

Feline urethral obstruction (urinary blockage) is a medical emergency and requires immediate attention. If this condition is not recognized and treated promptly it becomes life threatening. Our staff frequently provides emergency treatment to cats who have developed a urinary obstruction; this is why we feel it is important that feline owners have information that can help them recognize signs of this emergency at home.  Dr. Sarah Brawdy, an Emergency Doctor here at VSES, has provided an informative article which discusses the condition, how it is treated, and how to care for your feline companion after they return home.

So what exactly happens if my cat becomes blocked?

First, let's get back to the basics and review some anatomy and physiology. The kidneys filter the blood, remove excess fluid from the body, and aid in maintaining normal electrolyte balance in the body. the kidneys make urine,which travels down the ureters to the bladder. During urination, urine leaves the bladder and hopefully into the litterbox via the urethra.

When a cat becomes "blocked" or develops a urethral obstruction, they are unable to pass urine through the urethra. As a result, the bladder becomes very large, hard, and painful. Pressure increases in the upper urinary tract and the kidneys are no longer able to filter metabolic waste products and maintain normal electrolyte balance. The build up of these waste products and electrolytes makes the cat feel sick. Left untreated, these changes will ultimately become life threatening. This is due to high potassium levels in the blood that eventually result in a slow heartbeat and can lead to cardiac arrest.

How do I know if my cat may be blocked?

Urethral obstruction is a diagnosis that is made on physical examination by you veterinarian. However, there are important signs that you can watch for at home. These signs may include the following:

• Straining to urinate and with the absence of urination or production of only tiny amounts
• Licking excessinvely at the genital region
• Attempting to urinate in inapproproate places
• Vocalizing or crying
• Vomiting
• Lethargy
• Hiding
• Anorexia 
• Acting painful and restless

You may only see some of these signs if your cat is blocked at home. Even if you do not see your cat straining, it is important to follow up with your veterinarian if any of these signs are noted.  

So what causes a urethral obstruction?
The signs of a urinary blockage may look very similar to signs of a urinary tract infection or feline idiopathic cystitis (inflammation of the bladder). On physical exam these cats will have a large, firm, and very painful bladder (peach to small orange in size). A normal bladder should be small and soft to semi-firm. There are many possible causes of a urinary blockage.
 These include the following:

• Crystals or 'sand" in the bladder resulting in a urethral plug
• Small bladder stones (uroliths) that have become stuck in the urethra
• Tumors within the bladder and/or urethra or outside the urethra
• Scar tissue causing a stricture (or narrowing of the urethra)
• Urethral spasms
• Muscos plug (mucous/inflammatory cells) resulting from inflammation of the bladder or urethra
• Blood clots

How do you treat a urethral obstruction? 
Immediate treatment involves stabilization and relieving the obstruction. This procedure may be uncomfortable and painful and is therefore done under heavy sedation or anesthesia.  A urinary catheter is passed into the urethra and is advanced into the bladder to relieve the blockage. Oftentimes, resistance is met at the site of the obstruction and any material  (stones, mucous, crystals) obstructing the urethra is flushed back into the bladder.  The urinary catheter is secured and connected to a urinary collection bag. Typically the urinary catheter is left in for 48-72 hours, depending on how the cat is doing and how sick they were prior to the procedure. Hospitalization following the unblocking procedure is important, especially in the patients that are really sick when they are diagnosed.  When a cat is blocked, the kidneys are unable to make urine normally. Once the blockage is relieved, the kidneys will reestablish urine flow. The kidneys begin to make urine very quickly in order to correct the metabolic abnormalities that have been going on.  Sometimes these cats will make large amounts of urine very quickly (post obstructive diuresis) and can become severely dehydrated if they are not on IV fluids.  While in hospital, they are also started on medications for pain; medications that help relax the urethra, and antibiotics if they have a concurrent urinary tract infection.  Prior to going home, the urinary catheter is removed in hospital and they are observed for several hours to make sure they are urinating normally. Dietary changes are typically recommended if the cat has crystals or small stones in the urine. These are prescription urinary diets that work to dissolve crystals (and help prevent reblocking in the future).  Surgery is often recommended to remove bladder stones if they are the underlying cause of the obstruction. Once your cat is discharged from the hospital, it is important to watch for signs that may indicate reblocking has occurred. If you have any questions about your cat’s urinary status or if your cat is showing any of the signs listed above, it is best to contact your veterinarian. 

  Written by Sarah Brawdy, DVM