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This Deadly Indoor Habit Can Be Fatal to Your Pet

Convenient for you, but it can kill your pet within days. That's why I suggest you avoid it like the plague - especially this top one. It's far easier to prevent this pet-killing disease than you think. And you certainly don't want to regret it later.

cats urethral obstruction


  • Urethral obstructions, or urinary blockages, are extremely common in cats, especially overweight male cats on dry food diets
  • A urethral obstruction is a life-threatening emergency that can be fatal within a matter of days, which is why it’s important to check your kitty’s urine output on a daily basis
  • A significant risk factor for urinary blockages in cats is a dry food-only diet. Others include obesity, a stressful environment and a sedentary lifestyle

Editor's Note: This article is a reprint. It was originally published April 04, 2017.

If you're a cat parent, one of the best motivations I can think of for making litterbox scooping a once or twice daily routine is so you can keep a close watch on kitty's "output," and specifically, his or her urine output. This is especially important if there are male cats in your family.

The reason? The potentially life-threatening condition known as a urethral obstruction (UO).

How a Urethral Obstructions Forms

The urethra is a small tube that transports urine from your cat's bladder to the outside of the body. Urethral obstructions are usually urinary crystals or stones, or plugs of inflammatory material that form in the kidneys (a process known as urolithiasis).

The stone travels down into the urethra, blocking the passage of urine from the body. The urethra in male cats is longer and narrower than in females, so obstructions are much more common in males.

Feline urethral obstructions are extremely common and if not treated promptly, can result in death in a matter of days.

Symptoms of a Urinary Blockage

Even though the urethra is blocked, the kidneys continue to produce urine and the urine starts building up in the bladder, which begins to swell.

This can also quickly interfere with kidney function, because the job of the kidneys is to flush waste from the body, and when they aren't working properly, toxins accumulate in the bloodstream. Other symptoms of a UO can include:

  • Straining to urinate
  • Lethargy
  • Urinating small amounts, often with blood
  • Dehydration
  • Licking the genital area
  • Metabolic changes such as high potassium levels in the blood
  • Crying, restlessness or hiding due to pain
  • Decreased heart rate
  • Loss of appetite
  • Kidney damage
  • Vomiting
  • Bladder rupture

Risk Factors for Urethral Obstruction in Cats

Certain breeds may be predisposed to UO, including Persians, Himalayans, Russian Blues, Siamese, Birman and the Egyptian Mau.

A cat's living conditions, including stress, lack of environmental enrichment, obesity and a sedentary lifestyle, can also create risk factors for diseases of the lower urinary tract.

Sadly, dry food diets aren't often emphasized (or even mentioned) as being a significant risk factor for development of feline lower urinary tract disease, including urethral obstruction. This is a serious omission given what we know about the crucial role dietary moisture plays in feline physiology.

Study Shows Cats on Dry Food-Only Diets Are at Increased Risk for Urethral Obstruction

Since major pet food companies, who fund most pet food studies, aren't interested in research that points to a problem with their products, studies on the ways in which commonly fed pet foods affect pet health are impossible to find.

However, I did run across a study conducted by researchers at the Koret School of Veterinary Medicine at the Hebrew University of Jerusalem.1 The research team evaluated risk factors, clinical signs, outcomes and recurrence rates in 82 cats with UO and 82 control cats.

The kitties diagnosed with urethral obstruction had some interesting things in common:

  • They were significantly younger than the control cats; 82% were between 1 and 7 years old
  • They were significantly heavier
  • More were indoor-only cats than in the control group
  • Most were fed dry food only (68 out of 82, or 83%); 14 ate a combination of wet and dry food; and none were fed a diet of wet food only

In the healthy control group, almost half the cats ate both wet and dry food, or only wet food.

Why Your Cat's Food Should Be Loaded With Moisture

Dietary moisture is incredibly important to urinary tract health in cats. Your kitty doesn't have a strong thirst drive compared to other species. Felines are designed to get almost all the water they need from the food they eat.

Healthy cats don't lap up water like other animals do. Many kitties are obsessed with moving water, of course, but they're more interested in watching it or playing in it than drinking it. With very few exceptions, only cats with underlying disease drink a lot of water.

Often the disease involves their lower urinary tract, especially if they are suffering from chronic, moderate dehydration thanks to a primarily dry food diet. Cats in the wild hunt prey, and prey consists of about 75% water.

Canned cat food contains at least that much moisture. Dry food, on the other hand, contains only about one-tenth that amount.

If you're feeding your kitty mostly dry food, he's probably drinking more water than he would if his diet was high in moisture content. But as a general rule, cats on dry food diets consume only about half the water cats on moisture-rich diets consume.

Urethral obstruction in kitties falls into the category of feline lower urinary tract disease (FLUTD), which is a group of conditions affecting the bladder or urethra. Cats with FLUTD need to drink more water, urinate more and eat a moisture-rich diet. The first goal is to increase kitty's water intake. Many cats don't like to drink still water from a bowl, so if yours is one of them, consider a pet water fountain. Kitties are attracted to moving or flowing water, so a fountain should encourage more drinking.

Another important goal in managing FLUTD is to switch cats eating dry food to canned food, and then preferably to a fresh food diet. Feeding your cat only dry processed food can make her chronically dehydrated.

In addition, we want to reduce inflammation in the body by eliminating proinflammatory (high-carbohydrate) foods — particularly corn, wheat, rice and millet. A high-carb diet creates inflammatory byproducts and increases urinary pH in your cat's body that can ultimately inflame the lower urinary tract.

A nutritionally balanced, species-appropriate raw or gently cooked diet promotes a dilute and acidic urine pH that prevents most urethral obstructions. Ancestrally formulated fresh food diets are created with optimal mineral requirements in mind, unlike many dry food diets that can contain excessive amounts of trace minerals (such as magnesium) which increases the risk of stone formation.

Cats are designed to eat a meat-based, moisture-rich, carbohydrate-free diet, and when they receive this type of nutrition, in most cases their urinary tracts function exactly as they should.

Additional Recommendations

Obesity and indoor-only living have also been identified as significant risk factors for UO in cats. While your kitty is much safer living inside, she needs environmental enrichment to keep her stress level low.

Obesity in cats tends to go hand-in-hand with a sedentary lifestyle and a dry food diet, especially if your kitty enjoys an all-day all-he-can-eat buffet (also known as free-feeding). If your cat is overweight, it's really important for his overall health and quality of life that you help him slim down — but it must be done very gradually.

Sources and References

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