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Denver ER Doc
Denver ER Doc, Dog Veterinarian
Category: Dog Veterinary
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Experience:  Small Animal Medicine and Surgery Internship, Veterinary Acupuncture trained, Wildlife and Exotics
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What causes crystals to form in a dogs urine, and how do I

Resolved Question:

What causes crystals to form in a dog's urine, and how do I get rid of them? I've been told DL methionine will get rid of the crystals by changing the acidity of the urine. I've also been told changing the acidity will not get rid of the crystals. Can you also clarify whether or not Royal Cacnine has a prescription food that is not corn based?
Submitted: 6 years ago.
Category: Dog Veterinary
Expert:  Denver ER Doc replied 6 years ago.
Hi there,

Do you know what kind of crystals were identified in your pet's urine?

Dr. Paul
Customer: replied 6 years ago.
No testing has happened since the urine sample. I haven't been told about any specific kind, only that a change in diet is necessary to get rid of them. I would like to know what caused them so I can modify what I feed, but I haven't been able to get that information either. One vet told me Royal Canine would get rid of the crystals, and was not corn based. My vet called Royal Canine and was told their food is corn based. I hope you're beginning to see the contradictory information I'm receiving, and why I'm confused as to what to do.
Expert:  Denver ER Doc replied 6 years ago.
I am indeed.

The trouble is that different types of crystals are caused by different things, so without knowing what type of crystals they were seeing, I cannot tell you specifically what caused them.

If your veterinarian is recommending methionine to acidify the urine, I assume that the crystals that were identified form in alkaline urine.

The most common types of crystals or stones seen in alkaline urine are struvite crystals (magnesium ammonium phosphate). These are almost always caused by urinary tract infection with urease-producing bacteria, so usually dietary modification is not necessary if you can clear up the infection. Most dogs maintain a slightly acidic urine pH on standard diets in the absence of infection.

Again, this all assumes that your dog has struvite crystals. Very common, but may not be the case since your veterinarian is recommending dietary change. What you need to do is find out specifically from your veterinarian: 1) was a urinary tract infection confirmed, and 2) what types of crystals were seen. This will help determine whether any dietary modification is actually necessary.

This is a link to the page with Royal Canin's urinary diet. As you can see by the ingredient list, corn is the second ingredient:,293,12,1,Documents&MediaID=8042&Filename=Canine+URINARY+SO%C2%AE.pdf

Hope that helps. Happy to weigh in further once you have the above information from your veterinarian.

Dr. Paul

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