Feline urinary obstruction (FUP) is a very common disease in male ca en overlooked or missed by owners until the cat is very sick. Common clinical signs in male cats are frequent visits to the litter box with very little or no urine production, urinating small amounts of bloody urine, excessive grooming of the penis, lethargy, decreased appetite, vomiting, yowling (especially while in the litter box), or trying to urinate in strange places (i.e. on the carpet, in potted plants, etc.).
Feline urinary obstructions are more common in male cats than female cats because male cats have a long narrow urethra that can easily get blocked. Unlike male cats, female cats have short and wide urethras that allow them to pass urinary crystals and small urinary stones much easier. Urinary obstructions can happen in dogs, but it’s not as common as in cats.
What causes the urethra to become obstructed? Commonly, the urinary obstruction is caused by urinary crystals or small urinary stones. The two most commonly seen urinary crystals and stones in cats are calcium oxalate and struvite. Both form when the pH of the cat’s urine is either too acidic or basic. The pH determines which type of urinary crystal or stone the cat will get. Cats also get urinary obstructions from mucous plugs and blood clots. Both mucous plugs and blood clots are usually formed secondarily to an underlying issue such as crystals, stones, cystitis, etc.
When a cat gets a urinary obstruction, it becomes a life threatening emergency. Left untreated, your cat will die. The earlicr it is recognized and corrected, the better the prognosis for the cat. When a urinary obstruction occurs urine backs up into the bladder since the cat is not able to urinate. This can lead to acute kidney failure, electrolyte abnormalities, possible life threatening cardiac arrhythmias, and in extreme cases rupture of the bladder.
If your cat may be exhibiting signs of a urinary obstruction, the first thing to do is call your veterinarian. Your veterinarian will most likely see you right away. At the veterinary clinic, your veterinarian will get a thorough medical history and do a physical exam Cats with urinary obstructions will often have a very large firm bladder Your veterinarian will probably do blood work on your cat. Many cats will have abnormalities in their kidney and electrolyte values. It’s important to get the starting electrolyte values. After blood work, they will most likely place your cat under general anesthesia in order to pass a urinary catheter in the urethra and remove the urinary obstruction. Once the bladder is able to empty, a urine sample will be collected to see if there arc urinary crystals and what type they are. Most cats will be hospitalized to monitor urine output and to receive IV fluid therapy to help return the cat’s kidney and electrolytic values back to normal. In cases where the cat has had a urinary obstruction for a long time, permanent damage to the kidneys can occur.
Since most cats get urinary obstructions from urinary crystals, a special life-long diet will be needed Several prescription urinary diets help dissolve struvite crystals and prevent the formation of struvite and calcium oxalate crystals. With calcium oxalatc stones, surgery may be needed since this type of stone cannot be dissolved with diet change alone. Prescription urinary diets help regulate the pH of the cat’s urine and increase drinking so that the bladder is being flushed out more often. Every now and then there will be a cat that chronically has urinary obstructions. A special surgery, Perincal Urcthrostomy, essentially reroutes the urethra so that the cat has a short and wide urethral opening like a female cat.
We don’t know why some cats are more prone to urinary obstructions than others. In my experience, it tends to happen in young male cats (typically between 2-7 years of age). I’ve seen it with cats fed anything from cat chow to very expensive high end food. My own cat, Jack, was on a high end food and got a urinary obstruction. Luckily for Jack, I caught it early because I was studying for third year veterinary school midterms. Ironically one of the midterms was my Renal class and one topic was urinary obstructions. While I was studying, Jack kept going in and out of the litter box and producing nothing. After an hour, I took him to the vet school emergency (of course it was Saturday night) Successfully unblocked and treated, Jack has been managed with a prescription urinary diet for eight years.
Urinary obstructions can be life threatening if undetected. If you notice the clinical signs above, call your veterinarian right away. The worst (or best case scenario) is that your cat only has a urinary tract infection. Feline urinary obstruction shouldn’t be ignored. Don’t “wait – and – sec” since it could cause permanent damage to your cat’s kidneys and potentially cost him his life.