During the past three decades, a tremendous amount of information has been generated regarding the etiology, detection, treatment, and prevention of canine urolithiasis. No longer is surgical removal the only option available when dogs develop urolithiasis, nor is surgical removal the "treatment" of choice" in all patients. Although we know a lot more information about urolithiasis in dogs than we did three decades ago, there is still a lot that we don't know and remains to be discovered. Nonetheless, our ability to medically manage this disease in dogs has dramatically improved since 1973, and new knowledge continues to be generated. The purpose of the lecture is to provide an overview and an update on therapeutic options available for the four most common mineral types of uroliths in dogs.
Canine Urolithiasis Overview Table
Distribution of Mineral Types of Canine Urolths:
In 2003, the distribution of canine uroliths (n = 28,629) submitted to the Minnesota Urolith Center (courtesy of Dr. Carl Osborne and The Minnesota Urolith Center) were as follows:
Since 1981, prevalence of calcium oxalate in dogs has continued to increase, and it is equal to that of struvite now.Successful long-term management of urolithiasis is dependent upon an understanding of each mineral type.
Struvite (Magnesium Ammonium Phosphate) Urolithiasis
1. Background Information
urine becoming supersaturated with ammonium ions by the following reaction:
- the majority of struvite uroliths in dogs are infection-induced.
- urinary tract infections with urease-producing bacteria, such as staphlococci or proteus, result in
- when urine becomes supersaturated with ammonium ions (NH4+ ), these NH4+ can combine with
- magnesium and phosphate already present in urine, resulting in the formation of Magnesium
- Ammonium Phosphate uroliths.
- therefore, successful management and dissolution of infection-induced struvite urolithiasis in dogs
- is dependent upon appropriate treatment of the UTI along with dietary intervention.
2. Medical Dissolution Protocol
A. Drug intervention
- successful dissolution of infection-induced struvite uroliths is dependent upon eradicating the UTI that caused it to occur in the first place.
- appropriate antibiotic therapy, based on urine culture and sensitivity results, is a critical component of medical dissolution.a urine culture should be obtained pre-antibiotic treatment once dogs are receiving the appropriate antibiotic, the urine should be re-cultured 5 to 7 days later to ensure that the urine is sterile.
if the urine is not sterile by this time (5 to 7 days), you have a treatment failure (owner noncompliance, inappropriate dose, dog spitting antibiotic out, etc) and you need to re-evaluate your therapy.
- keep in mind that a urinalysis is not a sensitive way to evaluate whether the urine is sterile or not; therefore, a urine culture is necessary for monitoring a UTI.
- if the urine is sterile after 5 to 7 days of antibiotic therapy, continue administering antibiotics during the entire dissolution period.bacteria are often seeded throughout the entire stone, and therefore as you dissolve layers of the stone, you continually release bacteria into the urine.