Dystrophic mineralization in uremic dogs: an update

Abstract

Pathological mineralization is the abnormal deposition of minerals in body tissues, previously injured or not. In these lesions, in addition to calcium, other minerals can be found at lower concentrations. Classically, mineralization is divided into two types: dystrophic and metastatic. However, currently, there is no consensus among researchers on the type of mineralization that occurs in uremic dogs. The objective of this study was to elucidate the type of pathological mineralization that occurs in dogs with uremic syndrome through the correlation of biochemical examinations with gross and histopathological changes, given the existence of controversial information on this theme in the specialized literature. The Shapiro-Wilk, D’Agostino and Pearson tests were used to evaluate data normality distribution, and analysis of variance (ANOVA) was applied to compare the data between more than two groups. Additionally, the Dunnett’s multiple comparison test was used in the comparison between the Control Group (CG) and the Experimental Groups (G1, G2, and G3). Serum levels of urea, creatinine, total and ionized calcium, phosphorus, calcium-phosphorus product (CPP), parathyroid hormone (PTH), and albumin of 40 azotemic dogs with chronic kidney disease (CKD) were evaluated. Dogs were categorized by degree of azotemia (mild, moderate, and severe). Ionized hypocalcemia was observed in 97.5% (39/40) of the dogs, and no animals presented ionized hypercalcemia. Hyperphosphatemia was frequent (62.5%), especially in dogs with severe azotemia. PTH concentration increased with progression of azotemia, and high PTH levels were verified in 100% of the dogs with severe azotemia. CPP >60mg2/dl2 was observed in 75% (30/40) of the dogs. Of the 29 dogs that died during the study period, 16 were necropsied. Soft tissue mineralization was observed in 93.7% (15/16) of these dogs at gross and histopathological evaluation (HE and Von Kossa), regardless of the degree of azotemia, in nine organs/tissues: kidneys (75%), lungs (50%), stomach (31.2%), heart (25%), larynx (25%), intercostal muscles (25%), aorta (6.2%), intestines (6.2%), and tongue (6.2%). In one animal, the serosa of all segments of the small intestine showed whitish, rough, irregular, multifocal plaques of varying sizes, confirmed by histopathology as dystrophic mineralization of the longitudinal outer muscular layer, which presented necrosis of coagulation and of the intestinal serosa. This intestinal lesion has not been described in dogs with uremic syndrome to date. In conclusion, the laboratory and histopathologic data previously described, especially regarding tissue and vascular mineralization, which occur in association with previous degenerative/necrotic lesions in the absence of hypercalcemia in dogs with CKD, assist with clarifying inconsistencies found in the existing literature. Therefore, conceptually, mineralization that occurs in uremic dogs should be considered dystrophic.

Clinical, CT and ultrasonographic features of renal secondary hyperparathyroidism in a juvenile dog

“…29 Dystrophic mineralisation of soft tissues has also been described in uraemic dogs. 30 Interestingly, there was no major abnormality in the axial skeleton and included appendicular skeletal structures, despite severe osteopenia of the skull.…”

Clinical-pathological and immunohistochemical evaluations of cardiac lesions in cats with chronic kidney disease

“…The mineralization observed in both myocytes and tunica intima of the vessels, in 3/18 animals can be correlated to the deposition of minerals in tissues submitted to previous necrosis injury, that is, to dystrophic mineralization (Alfrey 2004, Cardoso et al 2019 verified that 100% of dogs evaluated showed endothelial lesions of different intensities, which was observed in only 1/18 of the cats in this study; however, it corroborates the study by Dantas & Kommers (1997), who reported that only 18% of the dogs had extrarenal uremic lesions such as vascular alteration associated with myocardial necrosis and mineralization. Coagulation necrosis and cardiac dystrophic mineralization were also observed in 43.7 and 25% of dogs with CKD, respectively, in the study conducted by Cardoso et al (2019). Lesions of this nature were attributed to cardiac vessel changes in cats with uremia and/or metabolic and hemodynamic changes caused by CRS, since it reinforces the hypothesis that a dystrophic lesion precedes mineralization in cases of degenerative, inflammatory, or necrotic lesions in uremic dogs.…”

Computed tomography examination of the os cordis in a lamb (Ovis aries Linnaeus, 1758)

“…Según Cardoso et al (18), esta patología consiste en el depósito anormal de minerales en los tejidos corporales, ya sea previamente lesionado o no.…”