Even though I have many videos and blogs regarding crystals found on urinalysis, I still get questions regarding this problem in my inbox multiple times every week. Obviously, this is a common problem, which, unfortunately is often treated with poor quality prescription diets or unnecessary antibiotics.
Quite commonly, a urinalysis will show crystals in the urine. The type of crystals will impact how the problem should be treated, if at all. The two most common types of crystals are oxalate and struvite. Oxalate crystals form in urine with a very low pH (generally below 6.5). Struvite crystals will form in urine with a high pH (generally above 7.5). Oxalate crystals are more common in certain breeds such as miniature schnauzers, shih tzus, maltese, yorkies, and pugs. Struvite crystals are often associated with bacteria in the urine and urinary tract infections. Struvite stones will form if urinary tract infections are left untreated and crystals are forming. Oxalate stones are not caused by infections, but infection can occur secondarily.
In general, diet manipulation can be used to eliminate crystal formation in the urine. As a general rule, diets high in grains and legumes tend to lead to higher urine pH, while diets with more meats and organs tend to produce lower urine pH. Diets high in moisture result in fewer crystals in the urine, mostly due to dilution factor. The more fluid that enters the bladder, the more dilute the urine, and the more often the bladder is flushed. Dogs and cats that take in very little moisture and urinate infrequently will be more prone to urine crystal production. Cats are desert animals and do not usually drink large volumes. When fed dry kibble, they are very prone to producing urine crystals, leading to the dreaded cystitis or lower urinary tract disease that causes so many cats to be fed prescription diets. If you MUST feed prescription diet, do your pet a favor and at least feed the high moisture canned or pouch version.
If your pet's urinalysis reveals a high pH and struvite crystals, that does not necessarily indicate antibiotics should be administered. I generally recommend an x-ray to see if any stones are present. If stones are present, antibiotics are not going to solve the problem. Surgery to remove the stones is recommended, or as a last resort, a prescription diet can be tried to dissolve the stones. The prescription diets are extremely low in protein and should not be fed for more than 30 days. They will only work on struvite stones. Once the stones are removed, a urine culture should be performed, and antibiotics chosen based on the results. Jumping from one antibiotic to another without knowing what you are treating can result in resistant bacterial populations that are very difficult to treat. Occasionally an animal will have a negative urine culture, but will still respond to antibiotics. I only recommend "trial" antibiotics if the animal is symptomatic (increased urine frequency, straining to urinate, blood in the urine) when the culture is negative.
Options to lower the pH naturally (struvite crystals) include feeding a high moisture, meat or fish-based species-appropriate diet, and adding acidifiers like fresh cranberries, apple cider vinegar, and fermented raw goat milk. Fermented raw goat milk has the added benefit of providing a natural source of probiotics to boost the immune system. Cranberries have a substance in them that inhibits bacteria from adhering to the bladder wall, increasing resistance to infection. Methionine, an amino acid, can also be given to lower the urine pH. This is the "magic ingredient" in many of the prescription diets. Instead of paying an exorbitant amount for a prescription food made with poor quality ingredients, you could buy this supplement.
Options to increase the pH naturally (for oxalate crystals) include asparagus, beets, broccoli, Brussels sprouts, cabbage, celery, chard, cauliflower, collard greens, cucumbers, eggplant, kale, lettuce, mustard greens, parsnips, peppers, pumpkin, turnips, sprouts, and watercress. Alkaline fruits include apples, apricots, bananas, berries, oranges, grapefruit, lemons, cantaloupe, cherries, figs, kiwi, mangoes, watermelon, honeydew melon, nectarines, pineapples, pear and tangerines. Many of these fruits and vegetables have the added bonus of increasing fluid flow through the kidneys and bladder to flush the crystals from the body.
If your pet is eating an optimal, high-moisture, species-appropriate diet and still makes abundant crystals, you might want to test your water. One client of mine bought pH strips and tested distilled water, filtered water, and spring water. All had a different pH. Once she chose the correct water, along with a high moisture, high quality diet, her dog's crystals and stones stopped forming.