Struvite Crystals in Cats

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Struvite crystals can form stones that irritate or even block the urinary tract. Struvite stones can appear in many types of animals, including cats.

What Are Struvite Crystals?

Struvite crystals are microscopic crystals that are found in the urine of some cats. Struvite specifically is a material that is composed of magnesium, ammonium, and phosphate. The crystals themselves can be perfectly normal but become problematic when they combine to form grit or stones of varying shapes and sizes. In some cases, the stones can be flushed out of the body or dissolved. In other cases, they must be surgically removed. They occur in both male and female cats.

Symptoms of Struvite Stones in Cats

Urinary blockages are most common in neutered male cats and life-threatening when not treated quickly. Signs of a urinary blockage include producing no or very little urine, pain, lethargy, and poor appetite.

Signs of Struvite Stones in Cats

Signs of struvite stones in cats to watch out for include:

  • Frequent use of the litter box
  • Urinating outside the litter box around the home
  • Straining to urinate
  • Painful urination sometimes accompanied by crying sounds
  • Excessive licking of the urethral area
  • Bloody urine
  • Poor appetite
  • Depression



Causes of Struvite Crystals

While struvite crystals may be normal, stones are not. There are several different causes of struvite stones in cats including:

  • Overly concentrated urine
  • High levels of phosphate, magnesium, and ammonium in the urine
  • Infection (less common in cats than in dogs)

An underlying cause for the development of struvite crystals is that many cats are reluctant to drink water from bowls. They've evolved over​ millennia to get most of their moisture from prey. This, partnered with a diet of dry cat food, can lead to crystal development in the cat's urine.

Diagnosing Struvite Crystals

If your cat is exhibiting some of the symptoms described above, it is best to schedule an appointment with your veterinarian right away. The vet will perform a physical examination and take a urine sample to examine the urine for any abnormalities. Bloodwork and x-rays may also be recommended. Additionally, ultrasounds are often used to view and determine the size, location, and number of stones present. This will help dictate the treatment options. Depending on the case, other tests may be conducted to determine if there are other medical conditions that may also be present.

Treatment

Struvite stones can often be dissolved. The goal is to create more acidic and dilute urine. Canned prescription diets that acidify the urine are ideal, but dry formulations are available for cats who won't eat wet food. Medications that acidify the urine can be used when a cat must be on another type of special diet. If an infection is present, antibiotics will be necessary as well. Your veterinarian will continue to monitor your cat until the stones are completely dissolved.

In some cases, struvite stones cannot be dissolved but have to be physically removed through surgery or other procedures.

How to Prevent Recurrence of Struvite Crystals

The best line of defense (and prevention) is a complete and balanced wet diet that promotes the formation of dilute and mildly acidic (pH of around 6.2 to 6.4) urine. High quality, over the counter wet foods are appropriate for prevention in many cases, but for cats who are at high risk for recurrence, a diet prescribed by your veterinarian may be a better option.

Additional steps to help prevent struvite crystals from recurring include:

  • Feed your cat small meals frequently which will help reduce fluctuations in urine pH.
  • Provide fresh water in multiple water dishes in different places. Try a fountain to pique your cat's interest. You can also offer chicken broth in addition to water to encourage your cat to drink more.
  • Provide a sufficient number of litter boxes placed in quiet areas.
  • Decrease stress by reducing major changes in routine.
If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.