Page 860 - Small Animal Clinical Nutrition 5th Edition

Chapter
43

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Canine Struvite Urolithiasis:

Causes, Detection,

Management and Prevention

Carl A. Osborne
Jody P. Lulich
Hasan Albasan
Laurie L. Swanson

“Diagnoses are often a matter of opinion rather than a matter of fact.
It is one thing to make a diagnosis, and another thing to substantiate it.”
Carl A. Osborne

late, 4% were of mixed mineral composition, 2% were calcium
PREVALENCE AND MINERAL phosphate, 2% were cystine and less than 1% were silica.
COMPOSITION The mean age at the time of MAP retrieval from dogs was
six years (range one month to 24 years). Females (85%) were
Currently, the second most common type of mineral encountered affected more often than males (12%; 3% of affected breeds
in uroliths from dogs is magnesium ammonium phosphate (MAP) were of unknown gender). A total of 239 different breeds were
hexahydrate, also known as struvite (Figure 40-1 and Table 38-8). affected,including mixed breeds (24%),Shih Tzus (11%),mini-
Struvite accounted for 43% of all canine uroliths submitted to the ature schnauzers (9%), Bichon Frises (8%), pugs (4%), dachs-
Minnesota Urolith Center from 2000 to 2006 and 39% (16,124 of hunds (4%), Labrador retrievers (3%), miniature poodles (2%),
40,612) of all canine uroliths submitted during 2007. Struvite Pekingese (2%), cocker spaniels (3%) and Lhasa apsos (2%).
accounted for 26% of canine upper urinary tract uroliths analyzed Struvite uroliths were more commonly removed from the lower
at the Minnesota Urolith Center from 2000 to 2006 (Table 38-9). urinary tract (99%) than the upper urinary tract (1%). They
Although urolithiasis is most commonly recognized in adult form in a variety of shapes and sizes (Table 43-1).
dogs,approximately 1.0% of the total canine uroliths analyzed at
the Minnesota Urolith Center were obtained from dogs less ETIOPATHOGENESIS AND RISK
than 12 months old. Of 800 uroliths retrieved from dogs less FACTORS
than one year of age,approximately 56% were struvite,23% were
purines (ammonium, sodium and calcium urate, uric acid), 8% Infection-Induced Struvite Uroliths
were compound uroliths (minerals in the center of uroliths were Sequential Steps in Urolith Formation
different from minerals in outer layers), 5% were calcium oxa- Urine must be supersaturated with MAP hexahydrate for stru-