Urolithiasis Problems in Finishing Pigs

Simple Summary The paper describes two cases of urolithiasis in finishing pigs on two farms (A and B). On both farms pigs died of urinary bladder rupture due to urethral obstruction with calcium carbonate calculi. An in-depth diagnostic examination to elucidate pathophysiological mechanismes consisted of analysis of mineral composition of feed, drinking water, mineral composition of urinary stones, blood parameters (minerals, a bone resorption marker, parathyroid hormone, vitamin D metabolites), biochemical urinalysis and microscopic examination of urinary sediment. Although mineral composition of feed and drinking water was similar on both farms urinary calcium and phosphorus excretion and composition of urinary crystals was different: low urinary phosphorus and high urinary calcium excretion and presence of calcium carbonate crystals in farm A, low urinary calcium and high urinary phosphorus excretion and presence of struvite crystals (magnesium ammonium phosphate) in farm B. Disturbances in calcium and phosphorus absorption and homeostasis was demonstrated but the examinations could not fully explain the pathogenesis. Further research has to focus on calcium and phosphorus levels in the feed, absorption and excretion of these minerals due to gut or urinary microbiota dysbiosis as well as on vitamin D content of the feed.Abstract This paper describes cases of urolithiasis in fattening pigs on two farms (A and B). Bladder rupture due to urethral obstruction with calculi was the principal finding during the necropsy of the pigs. An in-depth diagnostic examination was performed to elucidate possible pathophysiological mechanisms, namely Fourier-transform infrared spectrophotometry (FT-IR) analysis of the uroliths, blood analysis (farm A: 5 samples, farm B: 10 samples) for assessing concentrations of minerals, the bone resorption marker cross-linked C-telopeptide of type 1 collagen (CTX), parathyroid hormone (PTH), and vitamin D components, biochemical urinalysis (farm A: 5 samples, farm B: 7 samples), microscopic examination of urinary sediment (Farms A and B: 7 samples each), mineral composition of the feed, and analysis of the drinking water. Calcium carbonate was the main component found in stones from both farms, and calcium carbonate and struvite were the main components found in crystals from farms A and B, respectively. On farm A, urinary calcium excretion and urinary pH were high; on farm B, urinary phosphorus was high and urinary calcium was low with a normal urinary pH. The mineral compositions of the feed and drinking water were similar on both farms and could therefore not explain the difference between the two farms. Disturbances in calcium and phosphorus absorption and homeostasis might have been involved in these problems. Further research should focus on the calcium, phosphorus, and vitamin D levels in the feed and take into account other factors, such as the absorption and excretion of minerals due to gut and urinary microbiota.