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. Struvite and struvite crystals can be a normal finding in your cat’s urine at a low level but become problematic when the crystals combine to form grit or stones of varying shapes and sizes. These stones can be found in the urinary bladder, the urethra, or in the kidneys. 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
In many cases, stones can cause painful inflammation and irritation to the bladder wall and a life-threatening emergency can occur, urinary blockage, in which they produce no to very little urine. Some cats may not show symptoms immediately or minimal symptoms and may be found when your veterinarian is performing tests for another condition.
Symptoms of struvite stones in cats include:
Urinating outside the litterbox
Urinating small amounts of urine
Increased or decreased urination
Frequent trips to the litterbox
Vocalizing and/or straining when urinating
Change in color or odor of urine/ bloody urine
Excessive grooming and licking of genital area
Decreased appetite or not eating
Chronic urinary infections/cystitis
Causes of Struvite Crystals
According to VCA Hospitals, “in some cats, struvite bladder stones form as a result of a urinary tract infection, but this is less common in cats than in dogs. In most cases however, cats develop struvite stones in the absence of an infection. In these cases, the exact cause is unknown. A number of different factors have been found to contribute to these stones, including the formation of concentrated urine, increased urine pH (alkaline urine), and increased levels of magnesium and phosphorus within the urine.”
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 you notice any of the symptoms above, its best to contact your veterinarian immediately. At your veterinary visit, your vet will perform an exam and diagnostics to rule out the known causes of struvite crystals and stones and form a diagnosis.
- History: Your veterinarian with the help of the veterinary technician will obtain a history on your cat. This will include your cats’ behavior, including any changes to the environment, cat’s routine and schedule, and any other symptoms you have observed at home.
- Physical Exam: Your veterinarian will perform a physical exam of your pet
- Bloodwork and Urinalysis: 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 Susceptibility: A urinalysis sample should ideally be obtained via a cystocentesis which is a procedure where a needle is placed into the urinary bladder through the abdominal wall and a sample of urine is removed. 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 for struvite stones is based on the underlying cause and is tailored to the individual cat but in most cases, treatments are dissolving the stones via a prescription diet or surgical removal. Additional treatments can include pain medications, diet changes, increasing water intake, anti-spasmodic medication to help the bladder relax, fluid therapy, and reducing stress.
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 via rechecks (exams, radiographs, urinalysis, and/or ultrasound) 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.
If your cat has a urethral obstruction such as a bladder stone, your vet will need to relieve the obstruction quickly. To do this, they will most likely need to sedate or anesthetize your cat and will place a urinary catheter along with managing your cats’ pain and other symptoms.
How to Prevent Recurrence of Struvite Crystals
You can’t always prevent struvite crystals and stones in your cats urine and cats who have developed struvite bladder stones are more likely to experience a recurrence later in life. However, there are factors that are known to increase the chances of your cat having struvite stones which include obesity, decreased water intake, and one of the most common causes, stress. Read below to find out you can reduce these factors.
· Giving prescribed medications and diets as indicated by your veterinarian
- Monitor your cat's behavior and elimination patterns and be sure to alert your veterinarian to any changes or concerns.
- Keep your cats active with play and food puzzle toys to help prevent obesity.
- Increase water intake: Increasing water intake help prevent urinary issues in cats. You can encourage your cat to drink by providing various resources for water including water fountains, wide and shallow bowls, and having them on each floor in your home. Feeding wet food, a canned urinary prescription diet, and adding water to their food helps to provide your cats with more hydration.
- Enriched Enviorment: It is important to provide multiple and separated key environmental resources which include litter boxes, water, food, hiding spaces, places to perch, resting/sleeping areas, play areas, scratching areas and toys. This helps to decrease social tension and competition, decreases territorial motivations, decreases stress and fear, and provides choices which all help to prevent stress and create a safe environment.
- Stress Reduction: There are a variety of ways to help decrease stress for your cat. Phermones, Feliway and Feliway Multicat, and classical music such as Through a Cats Ear can help create a relaxed cat friendly environment along with an enrichment environment. Do your best to provide your cat with a routine and consistent schedule and be aware of the stress caused by changes such as construction in the home, vacation, etc.
- Appropriate Litter Box setup: In many cases, a cat's litter box is not set up properly, which can lead to stress and urinary issues. When it comes to litter boxes, there should be one litter box per cat in the home, plus one extra. If there is more than one floor in the home, there should be at least one litter box per floor. The larger the box, the better, boxes should be 1.5 times the length of your cat, and boxes should be located in open, well-ventilated areas and should be kept clean.
If you ever feel as though your cat is experiencing a urinary problem, especially if they are straining to urinate and seem uncomfortable, please seek veterinary attention.
Lulich, J P et al. ACVIM Small Animal Consensus Recommendations on the Treatment and Prevention of Uroliths in Dogs and Cats. Journal of Veterinary Internal Medicine, 30,5,1564-1574, 2016, doi:10.1111/jvim.14559
Struvite Bladder Stones in Cats. VCA Hospitals
Syme, Harriet M. Stones in Cats and Dogs: What Can Be Learnt from Them?. Arab Journal of Urology, 10,3, 230-9, 2012, doi:10.1016/j.aju.2012.06.006
Gomes, V.d., Ariza, P.C., Borges, N.C. et al. Risk Factors Associated with Feline Urolithiasis. Veterinary Research Communications, 42, 87–94, 2018, doi:10.1007/s11259-018-9710-8