Changes in Proportion of Canine Urinary Calculi Composed of Calcium Oxalate or Struvite in Specimens Analyzed from 1981 through 2001

Abstract

The objective of this report was to characterize 20-year changes in proportion of calcium oxalate (CaOx) calculi and struvite calculi in dogs, and associations with breed, age, and sex. In this retrospective study, results of analysis of urinary calculi from dogs were reviewed for specimens received between July 1, 1981, and December 31, 2001. Breed, sex, age, year of submission of the specimen, and mineral type(s) were analyzed statistically. CaOx or Struvite or both were contained in 18,966 of 20,884 (91%) specimens. For both sexes, a 20-year statistically significant increase was observed in the proportion of calculus specimens that contained CaOx. The increase in this proportion was greater in females (1% to 31%) than in males (18% to 82%). From 1998 to 2001, when proportions may have plateaued, the odds of specimens containing CaOx were markedly higher in 18 breeds, markedly lower in 5 breeds, and not significantly different in 13 breeds compared with crossbreds. For both sexes, a 20-year statistically significant decrease was observed in the proportion of calculus specimens that contained struvite. This decrease in proportion was greater for males (79-16%) than for females (97-68%). From 1998 to 2001, when proportions plateaued, the odds of calculi containing struvite were markedly lower in 20 breeds, markedly higher in 1 breed, and not significantly different in 15 breeds when compared with crossbreds. Breed, age, and sex were associated statistically with CaOx or struvite urolithiasis. In conclusion, there appears to have been a long-term increase in the proportion of specimens of canine urinary calculi that contain CaOx as well as a long-term decrease in the proportion of specimens of calculi that contain struvite for both male and female dogs. The rate of change appeared to begin leveling off in the period 1998 to 2001. The recent proportion of dogs with either CaOx-or struviteassociated urolithiasis may depend on breed, age, and sex, and on interactions among these 3 factors.Key words: Age; Breed; Dog; Secular trends; Sex.U rolithiasis is a common and often recurrent problem in dogs, although only a few minerals are commonly found in canine calculi. They include struvite (MgNH 4 PO 4 ·6H 2 O), calcium oxalate (either as the dihydrate or the monohydrate), 3 forms of calcium phosphate (hydroxyl apatite, carbonate apatite, or brushite [calcium hydrogen phosphate dihydrate]), urate (usually as the sodium or the ammonium salt), silica, and cystine. Sex, breed, and age differences in the propensity to form calculi and the type(s) of minerals involved have been observed. [1][2][3] During the past 20 years, several investigators have recognized what appears to be a progressive increase in the number of specimens of canine urinary calculi that contain calcium oxalate (CaOx) and a progressive decrease in the number of specimens of urinary calculi that contain struvite (Ling, unpublished data).2-7 The proportions of specimens that contain calcium phosphate, urate, silica, and cystine have apparently changed rela...

Evaluation of trends in urolith composition and characteristics of dogs with urolithiasis: 25,499 cases (1985–2006)

“…Evaluation of trends in urolith submissions to our laboratory revealed several important findings. Similar to results in another study 4 in which our laboratory group detected a significant increase in the proportion of CaOxcontaining uroliths by 2001, this trend was continued in the study reported here whereby CaOx was the most common mineral detected in uroliths submitted by veterinarians to our laboratory. A significant reciprocal decrease in struvite-containing uroliths was also apparent.…”

“…These changes in trends were not independent of sex, breed, and age, and 1 factor may influence another. 4 Reasons for the long-term changes in this trend were likely multifactorial and could have included demographic and nutritional changes during the period of the study. Factors may include feeding a more acidified diet, changes in mineral content of diets, an increase in obesity in dogs, and, possibly, a trend for people to favor owning breeds more prone to formation of CaOx-containing uroliths.…”

Elemental Content of Calcium Oxalate Stones from a Canine Model of Urinary Stone Disease

“…The elemental content in canine CaOx stones was compared with other characteristics of the stone or whole animal, in line with previous studies [27,36]. Ca levels did not demonstrate any significant relationship with characteristics of stone or animal.…”

“…CaOx has become the most common mineral detected in canine uroliths, as in humans [3,27]. Dogs also share many risk factors for stone disease with humans, such as being male and overweight [3,27–30]. These similarities suggest that the dog might serve as a model for urinary stone disease to help improve outcomes in both species.…”

Urolithiasis in dogs: Evaluation of trends in urolith composition and risk factors (2006‐2018)

“…Changing urolith trends in dogs have been recognized over the last several decades, with increases in the proportion of calcium oxalate (CaOx)containing uroliths and decreases in the proportion of struvitecontaining uroliths reported from various laboratories offering quantitative urolith analysis. [1][2][3][4][5][6] However, data from the Minnesota Urolith Center (MUC) in 2019 showed a higher prevalence of struvitecontaining uroliths compared with CaOx-containing uroliths. 7 Uratecontaining uroliths are typically the third most common type reported in dogs.…”