Cats are prone to urinary tract issues, and diet makes a difference in their urinary health. When cats form crystals in their urine, it hurts (like having tiny shards of glass in your bladder). It sets the stage for the formation of bladder stones and potential life-threatening urinary blockages.
A common medical term for the syndrome of pain and inflammation in the lower urinary tracts of cats is “feline lower urinary tract disease,” or FLUTD. Signs associated with FLUTD include:
- Bloody urine
- Frequent urination
- Straining to urinate
- Painful urination
- Urinating outside the litterbox
- Excessive licking of the lower abdomen and external genitalia
Causes of FLUTD include feline idiopathic cystitis (FIC), which is thought to be associated with stress, bladder stones, urethral obstruction (“blocked cat”), tumors, trauma, and urinary tract infection (UTI).
Crystals that can form in a cat’s urine (crystalluria) can be a precursor to bladder stones and urethral obstructions. Importantly, even if urinary crystals don’t progress to stones or blockages, they can irritate the bladder lining, causing uncomfortable lower urinary tract signs and inappropriate elimination (not using the litterbox). Crystals are not something you want to ignore.
Diagnosis of Crystalluria
The diagnosis of crystalluria is made by urinalysis. Fresh samples are the most reliable, so your veterinarian may want to retrieve a sample from your cat’s bladder during a visit. Cystocentesis is a procedure in which a fine needle is passed through the abdominal wall and urine is drawn directly from the bladder. Most cats tolerate this procedure well, but some require sedation.
If you must get the urine sample at home, you can either observe your cat until he or she heads to the litterbox and catch a sample into a tiny cup (this can be challenging) or switch out your litter for non-absorbent pellets you can get from your veterinarian. Either way, fresher is better, so deliver urine samples to your veterinarian immediately, or refrigerate them until you can drop them off. Crystals can spuriously form in urine if the urine sits around for a while, making the interpretation more difficult, so relatively fresh samples are best. Your veterinarian may use other factors, like the presence of inflammatory cells and/or blood in the urine, to determine the significance of any crystals identified.
The two biggest concerns when crystals are present in the urine are that they can stick together and become bladder stones, and/or they can cause urethral obstruction, which is a medical emergency requiring immediate intervention, especially in male cats. If crystals are identified in your cat’s urine, further diagnostics, including urine culture to rule out infection and X-rays and/or abdominal ultrasound to look for stones, may be recommended.
Treatment Protocols
Treatment involves eliminating any stones and taking steps to prevent recurrence. Treatment options for struvite crystals include surgical removal of stones from the bladder or medical dissolution of stones using a prescription urinary stone-dissolving diet. Stones often dissolve within a few weeks, although it can take a few months.
Unfortunately, dietary dissolution does not work for calcium oxalate stones, and their treatment usually involves surgical removal of any stones and a full medical workup to identify and treat any underlying disorders.
Management
Urinary crystal prevention involves proper diet and promoting dilute urine by increasing water consumption. The more dilute the urine is, the less likely crystal formation is. Prescription urinary diets are usually low in magnesium and phosphorus and help maintain a urine pH unfavorable to crystal formation.
Strategies for increasing your cat’s water consumption include feeding canned food instead of dry, adding water to meals, and introducing a water fountain. Cats often find these commercial fountains interesting and may ingest more water from them, but this is not true of all cats.
