Struvite Crystals in Cats

Struvite crystals can form bladder stones in cats, which result in painful urination. They can also form mucus plugs which may block the flow of urine. While the presence of struvite is considered normal in cats, problems occur when the struvite clumps to form stones or plugs. Here's what causes struvite crystals in cats and how to treat and prevent them.

What Are Struvite Crystals in Cats?

Struvite crystals are microscopic crystals sometimes found in the urine of cats. Struvite is a mineral material composed of magnesium, ammonium, and phosphate. Small numbers of struvite and struvite crystals can be normal in your cat’s urine, but they become problematic if the crystals combine to form stones or merge with mucus to form mucus plugs.

Struvite stones can be found in the urinary bladder, the urethra, or the kidneys. Mucus plugs can become lodged in the urethra and cause a urinary blockage, particularly in male cats. Some types of urinary tract infections can make cats more likely to develop struvite crystals. Struvite crystals may also be seen in some cats with recurrent or chronic cystitis.

Symptoms of Struvite Crystals in Cats

Some cats with excess struvite crystals experience few or no symptoms at first. The crystals may be found when your veterinarian is performing tests for another condition. When struvite crystals or stones begin to cause problems, cats may show several signs of illness:

Peeing Outside the Litterbox

A cat with struvite crystals or stones may experience pain when peeing and may try to handle the discomfort by avoiding the litterbox. Avoiding the litterbox doesn't always mean a urinary issue though. Some cats are just very picky about the specific type of litter you provide in the box.

Small Amounts of Urine

In many cases, stones can cause painful inflammation and irritation to the urethra and/or bladder wall. These cats may pee in small amounts because of pain, or they may have a urinary blockage, which is a life-threatening emergency in which a cat can eliminate very little to no urine.

Frequent Trips to the Litterbox

A cat with crystals or a stone may feel the urgent need to urinate and visit the litterbox frequently in an attempt to pass urine. They may only pass a small amount or no urine, but the pressure and discomfort of the need to urinate will not decrease.

Vocalizing and/or Straining When Urinating

The crystals may have formed a mucus plug or stone that is blocking or partially blocking the urethra, making it very uncomfortable for a cat to urinate. You may hear your cat crying out when they try to pee in the litterbox. You may also see them straining in the box, but producing little or no urine.

Change in Color or Odor of Urine

Crystals and stones can irritate and inflame the bladder wall, causing it to bleed. As result, your cat could pass bloody urine that may also have an odor if infection is present.

Excessive Grooming and Licking of Genital Area

The pressure of crystals or a stone, and the pain of urination, may trigger a cat to excessively groom and lick the genitals to relieve the discomfort.

Lethargy

If the crystals have formed a stone in a kidney or ureter, it could affect kidney function and make the cat depressed and lethargic. If there is a urinary blockage, the buildup of toxins will make the cat feel extremely sick.

Decreased Appetite

Your cat may not want to eat much because of the pain and illness associated with excess struvite crystals, stones, or mucus plugs.

Changes in Thirst

A cat with struvite crystals or stones may drink more water than usual. However, if they feel sick enough, they may avoid water altogether.

What Causes Struvite Crystals in Cats?

Several different factors have been found to cause excess struvite crystals in cat urine that form struvite stones and mucus plugs. These include concentrated urine, increased urine pH (alkaline urine), and increased levels of magnesium and phosphorus within the urine.

An underlying cause for concentrated urine is that many cats are reluctant to drink enough water. 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.

How Vets Diagnose Struvite Crystals in Cats

If you notice any of the symptoms above, contact your veterinarian immediately. The veterinarian will perform an exam and diagnostic tests to rule out the known causes and form a diagnosis. Here are all the ways that your vet can diagnose struvite crystals:

• History: Your veterinarian, with the help of the veterinary technician, will obtain a history on your cat. This will include your cat's behavior, any changes to the environment, the cat’s routine and schedule, and any other symptoms you have observed at home.
• Physical Examination: Your veterinarian will perform a physical exam of your cat.
• Urinalysis and Blood Work: By obtaining and running bloodwork and a urinalysis, your vet will be able to see how your cat’s internal organs are functioning as well as check for dehydration, bladder inflammation, and infection.
• Urine Culture and Sensitivity: A urine culture test is a method of identifying the specific bacteria that may be causing a urinary tract infection. It involves placing a urine sample on a special medium, incubating the sample so the bacteria can grow, and then identifying the bacteria. A second test (a sensitivity test) is usually conducted to determine the most effective antibiotics to use against the bacteria involved.
• X-rays and Ultrasound: These are done to assess if the bladder appears abnormal or contains bladder stones. Radiographs are the most effective way to diagnose bladder stones because most bladder stones (including struvites) are visible on radiographs. On radiographs, struvite stones typically look like smooth rocks or pebbles within the bladder. Ultrasound may also be used to visualize bladder stones.

Treatment

Treatment for struvite stones is based on the underlying cause and is tailored to the individual cat. In many cases, cats need surgery to remove stones or a special diet to dissolve stones. Additional treatments may include pain medications, diet changes, increasing water intake, anti-spasmodic medication to help the bladder relax, fluid therapy, and reducing stress. Your veterinarian will prescribe antibiotics if an infection is present.

Struvite stones can sometimes be dissolved by making the urine more acidic and dilute. Canned prescription diets that acidify the urine are ideal, but dry formulations are available for cats who won't eat wet food. Alternatively, medications to acidify the urine can be used when a cat must be on another type of special diet.

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

If your cat has a urethral obstruction from a bladder stone or mucus plug, your vet will need to relieve the obstruction quickly. The vet will sedate or anesthetize your cat and will place a urinary catheter. The cat will be hospitalized for fluid therapy, pain management, and monitoring.

After treatment, it's important to stay in contact with your veterinarian will continue to monitor your cat via rechecks (exams, radiographs, urinalysis, and/or ultrasound) until the stones are completely dissolved.

Prognosis for Cats With Struvite Crystals

The prognosis for cats with struvite crystals depends on the severity of their condition and how they respond to treatment. Most will recover with proper care, but cats who have developed struvite bladder stones are more likely to experience a recurrence later in life.

How to Prevent Struvite Crystals

Although it's not always possible to entirely prevent struvite crystals and stones in your cat's urine, several risk factors such as obesity, low water intake, and stress can increase their likelihood. Consider these strategies to mitigate these risks.

• Water: Encourage your cat to drink by providing various water sources, such as fountains and both wide and shallow bowls, on each floor of your home. Feed wet food, ideally a canned urinary health diet. Or, add water to dry food to provide more hydration.
• Resources: Provide multiple, separate key environmental resources such as litter boxes, water, food, hiding spaces, places to perch, resting/sleeping areas, play areas, scratching areas, and toys. This creates an enriched environment that can decrease fear and stress, as well as social tension, competition, and territorial problems in multi-pet households.
• Activity: Keep your cat active with play and interactive toys, such as food puzzles, to keep them engaged and help prevent obesity.
• Pheromones: To help reduce your cat's stress, try pheromone products, such as Feliway, to help create a relaxed cat-friendly environment. Stick to a routine and provide quiet spaces around the home.
• Litter: Make sure the litter box is set up appropriately. A poor litterbox experience can lead to stress and urinary issues. Aim for one litter box per cat in the home, plus one extra. Place at least one litter box on each floor of your home. The larger the box, the better, meaning that boxes should be 1.5 times the length of your cat. Place litterboxes in open, well-ventilated areas, and keep them clean.