Urethral Obstruction in Cats

Major obstructions of the urethra can occur with the first episode of FLUTD or during subsequent attacks. With partial or complete obstruction of the urethra, the lower abdomen becomes distended and painful to touch. An obstructed cat spends a lot of time straining to urinate (many owners mistake this for constipation) without producing any urine.

Female cats do not obstruct as frequently as males, because their urethra is wider and crystals and plugs pass easier. However, females can become obstructed with urethral uroliths.

As pressure increases in the upper urinary tract, the kidneys fail and stop making urine. Wastes build in the blood, leading to uremia (a toxic buildup of urea). The cat loses her appetite, acts sluggish, and begins to vomit. If unrelieved, irreversible kidney damage occurs, leading to death. Thus, it is of vital importance to relieve the obstruction as soon as possible. Keep in mind that cats often seek seclusion when they are ill or in pain; therefore, a cat with symptomatic FLUTD should not be allowed outdoors.

Treatment: A cat with a plugged urethra needs immediate veterinary attention. This is an emergency with potentially life-threatening consequences. An obstructed male often protrudes his penis. You can massage the penis by rolling it between your thumb and index finger. This may crush the plug and allow the material to be expelled. Even if this is successful, veterinary attention and possible hospitalization are required.

Even if you can remove the plug so the cat can now urinate, you must take the cat to your veterinarian for follow-up veterinary care. Any plugs or crystals that are passed or collected should be analyzed so the correct treatment plan can be developed.

To relieve an obstruction, your veterinarian should first relieve the pressure in the bladder by emptying it via cystocentesis, a procedure in which a fine needle attached to a syringe is inserted into the bladder through the abdomen and urine is drawn into the syringe. This allows time for the kidneys to start functioning again and the cat to be stabilized with intravenous fluids prior to sedation. Relieving the obstruction must be done under sedation or anesthesia. Your veterinarian will insert a small, soft, rubber or flexible polyethylene catheter through the urethra into the bladder to relieve the obstruction. Intravenous fluids are continued to rehydrate the cat and increase the flow of urine. Antibiotics may be prescribed to prevent or treat an associated bladder infection. After obstruction, many cats need continued intravenous or subcutaneous fluids for several days, until kidney function returns to normal and the cat is voiding normally.

Following discharge from the veterinary hospital, the cat should be placed on a special diet; which diet depends on the type of crystals found in the urine. For cats with magnesium phosphate crystals, diets such as Hill's Prescription Diet Feline s/d, Eukanuba Low pH/S, Purina UR St/Ox, Royal Canin Control Formula, Royal Canin Dissolution Formula, and Royal Canin Urinary SO 30 help dissolve any residual struvite crystals or stones in the urinary bladder. These foods are low in magnesium and aid in maintaining a normal acid urine. In cats fed these special diets exclusively, signs associated with FLUTD will normally cease within the first five to seven days. To completely dissolve all residual struvite crystals or stones, the diet should be followed for one to two months. These diets, however, are high in salt and ordinarily are not used as a maintenance food. It is important to feed only the prescribed diet. Do not feed fish, shellfish, cheese, vitamin-mineral supplements, or table scraps. These foods contain extra magnesium and also produce an alkaline urine.

During and immediately after the dissolution process, you may be asked to monitor your cat's urine pH at home or to bring in a urine specimen to be checked for struvite crystals under the microscope.

For those plugs or stones that consist of nonstruvite compounds, such as calcium oxalate, there are also diets that will be of some assistance to prevent recurrence. These include Eukanuba Moderate pH O, Purina UR St/Ox, and Royal Canin SO 30.

No matter what type of urolith is present, surgery may be the best option for your cat, especially if the obstruction cannot be resolved. Your veterinarian will discuss the options with you.

This article is excerpted from “Cat Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.

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