Senior Dogs, Urinary Crystals & Bladder Stones: Causes, Types, and Prevention
- Katie A
- Jan 18
- 6 min read
Disclaimer: This content is for informational purposes only and reflects personal experience. It is not medical advice and is not a substitute for veterinary care. Always consult your veterinarian for diagnosis and treatment recommendations tailored to your dog.
Key Takeaways for Senior Dog Parents on Urinary Crystals and Bladder Stones
Urinary crystals, infections, and bladder stones can exist without obvious symptoms, especially in senior dogs.
Struvite crystals are commonly linked to UTIs and are often treatable with antibiotics and prescription diets.
Not all stones are the same—some cannot be dissolved with diet and may require surgery.
Prescription urinary diets are usually short-term medical tools, not lifelong nutrition plans.
Senior dogs need lower mineral levels, adequate hydration, and regular lab work to help prevent recurrence.
Eddie’s Story
Eddie had his senior wellness labs done in December, and his urinalysis showed struvite crystals along with bacteria, indicating a urinary tract infection (UTI). His veterinarian prescribed Royal Canin Urinary SO for Small Breeds to help dissolve the crystals and adjust his urine pH, along with Amoxicillin to treat the bacterial infection.
Because Eddie had a recent history of struvite crystals (from lab work done in March 2025 while we were in Las Vegas), the veterinarian recommended that we follow up with our primary care vet for a physical exam and diagnostic imaging to rule out bladder stones. Senior dogs can be prone to crystals and bladder stones.
About a month after starting the prescription food and antibiotics, we visited our primary care vet. They performed both X-rays and an ultrasound.
X-rays are good at detecting larger stones, but they can miss smaller stones or crystals.
Ultrasound can detect small stones and crystals, but it doesn’t always clearly show large mineralized stones.
Using both gives a more complete picture of what’s happening in the bladder.
They also ran another urinalysis, and thankfully Eddie was clear of crystals and bacteria. After reviewing his results and overall health, our vet said Eddie could safely transition back to his regular diet: Lotus Oven-Baked Senior Small Bites. He reviewed the ingredients and felt they were appropriate for Eddie.
What Are Struvite Crystals in Dogs?
Struvite crystals are microscopic crystals made of magnesium, ammonium, and phosphate. In dogs, they often form when:
Urine becomes too alkaline (high pH)
A bacterial urinary tract infection is present
Excess minerals are present in the diet or body
Struvite crystals can clump together and form struvite stones if not treated. In dogs, struvite crystals are commonly associated with UTIs, especially because certain bacteria raise urine pH and promote crystal formation.
The good news: struvite crystals and stones can often be dissolved with diet and antibiotics, as long as they are caught early and stones are not too large.
Other Types of Crystals and Stones in Dogs
Not all urinary crystals are the same. Common types include:
Calcium Oxalate
Very common in senior dogs
Often linked to genetics, age, and metabolic factors
Cannot be dissolved with diet once stones form
Usually require surgical removal if stones are present
Urate Crystals
More common in Dalmatians and dogs with liver issues
Can sometimes be managed with diet and medication
Cystine Crystals
Caused by a genetic condition affecting amino acid metabolism
More common in male dogs
Each type of crystal requires a different dietary and medical approach, which is why proper diagnosis is critical.
Why Prescription Urinary Diets Are Used
Urinary prescription diets are not “regular” dog food. They are formulated to:
Adjust urine pH
Control mineral levels
Increase water intake
Help dissolve certain crystals and stones (like struvite)
My vet explained that if I hadn’t told him Eddie was eating Royal Canin Urinary SO, he might have been concerned that Eddie had kidney disease based on the lab values alone. These diets intentionally change urine chemistry, which can alter lab results.
Prescription urinary diets are not always meant to be long-term, especially once crystals and infections have resolved.
Royal Canin Urinary SO works by:
Encouraging dogs to drink more water
Diluting urine
Creating an unfavorable environment for crystal formation
That said, I personally wasn’t a fan of the ingredient list. It contains brewer’s rice and corn, which are more starchy fillers and are not nutritious, and it lacks extras like probiotics or joint-support supplements that are especially important for senior dogs. Eddie would eat it, but sometimes I had to coax him to finish his bowl. (See previous blog article on pet food ingredients)
I appreciated that our vet does not sell prescription food at his clinic. He prescribes it when medically necessary, but he’s transparent that it’s not always ideal for long-term nutrition.
UTIs, Stones, and Senior Dogs
Senior dogs can sometimes have one-off crystal findings that don’t lead to stones. However, Eddie’s case required extra caution because:
He is male (UTIs are less common in male dogs)
His urine sample was collected by cystocentesis (directly from the bladder)
Bacteria was present, raising concern that stones could be harboring infection
Thankfully, imaging showed no stones, meaning there was no hidden source of recurring infection.
While the imaging and follow-up visit cost over $300, pet insurance made it manageable—and the peace of mind was worth it.
A Previous Experience With Prescription Food
When we were in Las Vegas, Eddie was previously prescribed Hill’s Science Diet Urinary/Metabolic after struvite crystals were found.
At the time, I asked the veterinarian if Farmina’s clinical urinary diet could be prescribed instead. My reasoning was that Farmina offers clinically formulated veterinary diets while also using ingredients I felt were more nutritious and higher quality overall. Unfortunately, that option wasn’t available through that clinic, and that vet would not even consider it or look into it.
Unfortunately, Hill's Science Diet Urinary/Metabolic food didn’t work for us:
Eddie disliked the taste
The kibble was too large for his small mouth and limited teeth
He consistently left food in the bowl, even after a two-week transition
Because Eddie wasn’t eating enough, I kept him on Lotus Oven-Baked Senior Small Bites, which has optimized (lower) mineral levels for senior dogs.
I am glad that Eddie's veterinarians in Texas actually considered the palatability of the prescription food and size of kibble for Eddie's needs. They actually listened and addressed my concerns about the nutrition of the prescription diets. So, it's also important to find a vet that cares about your concerns.
Symptoms of Bladder Stones and Urinary Issues in Dogs
Some dogs show obvious symptoms, while others—especially senior dogs—may show very subtle or no signs at all.
Common Symptoms
Straining or difficulty urinating
Frequent attempts to urinate with little output
Blood in the urine
Accidents in the house or loss of housetraining
Excessive licking of the genital area
Pain or discomfort when urinating
Foul-smelling or cloudy urine
Lethargy or decreased appetite
Emergency Signs (Seek Veterinary Care Immediately)
Inability to urinate at all (especially in male dogs)
Crying out or signs of severe pain when trying to urinate
Swollen or painful abdomen
Urinary blockages are life-threatening, particularly in male dogs, and require immediate veterinary intervention.
Signs Aren’t Always Obvious
What surprised me most is that Eddie showed no obvious symptoms:
Normal energy
Daily walks
Normal urination frequency and volume
No accidents or discomfort
I never would have known he had a bladder infection or crystals without routine senior lab work.
Nutrition and Prevention for Senior Dogs
As dogs age, their nutritional needs change. Senior dogs typically need:
Lower levels of minerals like phosphorus, calcium, and magnesium
High-quality, easily digestible protein
Adequate moisture intake
Joint and mobility support
Excess minerals can contribute to crystal and stone formation, especially in older dogs. That doesn’t mean seniors should eliminate these minerals—they still need them, just in carefully balanced amounts.
Prevention Tips
Final Thoughts
Eddie’s experience reinforced how important routine senior care is. Crystals and UTIs can exist without obvious symptoms, and early detection can prevent painful stones or surgery down the road.
Prescription diets have their place, especially during active crystal or infection treatment—but long-term nutrition should always be discussed with your veterinarian, especially for senior dogs.
This article reflects our personal experience and is not medical advice and is not a substitute for veterinary care. Always consult your veterinarian for diagnosis and treatment recommendations tailored to your dog.
Sources and References
The information in this article is informed by veterinary guidance and reputable animal health resources, including:
American College of Veterinary Internal Medicine (ACVIM) – Canine urolithiasis and urinary disorders
Merck Veterinary Manual – Urinary tract diseases and bladder stones in dogs
American Veterinary Medical Association (AVMA) – Urinary tract health and diagnostics
VCA Animal Hospitals – Urinary crystals, bladder stones, and urinalysis in dogs
Cornell University College of Veterinary Medicine – Canine urinary tract disease education
Royal Canin Veterinary Diets – Clinical nutrition for urinary health
Hill’s Veterinary Resources – Urinary stone types and management in dogs
These sources provide general educational information and clinical overviews. Individual diagnosis and treatment plans should always be determined by a licensed veterinarian.
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