URINARY TRACT ISSUES IN DOGS AND CATS
(Struvite stones and crystals)
By Alison Galligan
What are struvite stones and crystals?
They’re a type of bladder stone that can occur in both dogs and cats - also known as ‘triple phosphate’ and ‘magnesium ammonium phosphate’ stones. Regardless of what name they’re given they can cause serious problems for your pet and can be life-threatening if not treated quickly and appropriately. Such stones account for over one-third of all urinary tract stones in dogs and about half of all urinary stones in cats - usually most often in females from about 6 years of age.
Causes and symptoms
Causes can include extremely alkaline urine (often from a biologically inappropriate diet), high steroid use, abnormal urine retention, a urinary tract infection, or another urinary tract disorder. Some pets with bladder stones show no signs, but common symptoms include frequent urination, straining to urinate, an abnormal urinary stream (for example, the dog lifts his leg and maybe a few drops come out, and then a few drops more), urinating in inappropriate places (especially if it’s an indoor cat), cloudy or bloody urine, and sometimes increased thirst.
(It’s extremely important to note that self-diagnosis and treatment is not an option if your cat or dog is presenting any of the above signs. UT issues should always be immediately referred to your vet and dealt with quickly to prevent complete blockage of urine flow which should be regarded as a medical emergency.)
If there’s a lot of inflammation present, the bladder may be enlarged. And sometimes the stones can actually be felt through the abdominal walls. Your vet will take urine samples to check for abnormalities. A urinalysis will provide information about the presence of blood, protein, glucose, ketones, and bilirubin. It will also determine the concentration of urine, which is a measure of kidney health and can be a contributing factor to stone formation. A urinalysis will also pick up the presence of white blood cells indicating inflammation or infection.
A urine culture and sensitivity test will reveal if there is bacteria present and can also determine what medication will be most effective in clearing the infection. Because certain bacteria can exacerbate struvite formation, this is a very important step your vet should not overlook. However, some pets experience bladder inflammation with crystals or stones, but no infection is present. In this case, a different management protocol is required. X-rays and ultrasounds may be used to determine the size, shape, and location of the stones and to assess different treatment options.
Treating crystals or stones
If your pet has crystals or stones that aren’t completely blocking the urethra, making it possible for urine to pass, the situation can often be managed with medication and dietary adjustments. pH strips can usually be bought from your vet to check urine pH at home so you can check when it’s in or outside the recommended range - this should be done first thing in the morning before feeding your pet.
The first thing to do for a pet with crystals or stones is to create a healthy urine pH that is neither too acidic nor too alkaline. A pH of 7 is neutral. Everything above 7 is alkaline, and everything below 7 is acidic. Dogs and cats, as carnivores, should have a slightly acidic urine pH, optimally between 6 and 6.5. We want to maintain the urine pH at no more than 7, because a higher pH will predispose the animal to developing struvite crystals.
To reduce urine pH – which is the goal in most UT/struvite situations – you must feed your pet a low-carb, grain-free, potato-free, and preferably fresh or at least canned food diet for the increased moisture content. When dogs and cats who are designed to eat meat are fed a grain-based diet or a starch-rich diet, the starch alkalizes urine pH, which can lead to the development of struvite crystals and stones.
Often, a pet’s urine pH can be maintained naturally between 6 and 6.5, a good healthy range, on a species-appropriate diet. Dry pet food causes an increase in urine concentration, which can contribute to crystal and stone formation. Creating more dilute urine by offering a moisture-rich diet is critical to avoiding a recurrence of stones or crystals. Therefore kibble should always be avoided when feeding a cat or dog with UT issues - raw feeding provides a more appropriate fluid content but the addition of extra fluids is always recommended. A species-appropriate diet in combination with infection management is often effective at dissolving struvite stones, but it can take a few weeks to several months for the stones to completely disappear.
Stones located in the urethra or the ureters (the tubes that connect the kidney to the bladder), typically must be removed surgically along with any stones that don’t dissolve despite dietary changes and medical management.
Surgery to remove a bladder stone is known as cystotomy. Depending on the patient and the location and size of the stone, there are some other less invasive procedures that might be appropriate. These include a technique called laser lithotripsy that breaks down stones into smaller pieces that can then be voided out, and a procedure called voiding urohydropropulsion, which is a technique that involves manually expressing stones out through the urethra while the patient is sedated.
Prognosis/healthy UT maintenance
If your pet has been diagnosed with struvite crystals or stones it’s important that you continue treatment until the condition is resolved. A urinalysis should be completed monthly until all the crystals are dissolved and then every six months to ensure that no crystals or stones are forming.
As diet plays such a vital part in maintaining urinary tract health it’s important to feed a species appropriate diet. As a raw feeding group we would always advocate feeding a prey model raw diet which will help provide your pet with adequate fluids to help prevent urinary tract issues. Cats in particular are more likely to need additional fluids in their diet - as desert creatures who’ve never forgotten their origins they have a low thirst drive so adding extra fluids to their diet is always a bonus. Above all the starting point for a healthy urinary tract in both dogs and cats is fluids, fluids and more fluids - keep them flushed out!
**Disclaimer-This article is for informational purposes only. Should you have any medical concern speak with your vet.**