A blocked cat cannot urinate due to a blockage within the urethra (the tube-like passageway for urine from the bladder to the outside). This blockage leads to a painful enlargement of the bladder and a buildup in the blood of the body’s toxins and wastes that are normally eliminated with urination. Both of these cause loss of appetite, vomiting, weakness and painful straining in or out of the litter box. This condition will progress to a painful death if the obstruction is not relieved.
The animal most likely to become blocked is a male cat, due to the long length and narrow width of his urethra. Female cats and either gender of dogs are less likely to become blocked.
Material accumulating in the urethra causes the blockage. This material is made up of bacteria, infection fighting cells, and urine crystals. Bladder infections and certain cat foods raise the pH (often up to 8.0-8.5) producing an alkaline urine. This promotes the formation of certain crystals and stones. A healthy urine is generally thought to have a pH of 6.0-6.5.
The cat is usually anesthetized to allow the passage of a urinary catheter into the urethra. This is usually sutured in place to allow flushing out of the bladder. Fluids are given to stabilize the patient and to encourage flushing out of the built up urine toxins and wastes. Antibiotics are given in the hospital and will be continued at home to resolve the urinary tract infection. A special diet is usually recommended to lower the pH of the urine to dissolve the crystals formed there. Once your cat returns home the special diet and antibiotics will be continued. You will need to monitor eating, drinking, attitude and urination closely. Many blocked cats will need to be on a special diet for the rest of their life to prevent future urinary tract problems.