Urolith Formation Research Articles

Fluoride Accumulation in Groundwater from Semi-arid Part of Deccan Volcanic Province, India: A Cause of Urolithiasis Outbreak

Groundwater fluoride and health problem was meticulously studied for dental and skeleton fluorosis except few studies on urolithiasis. Urolithiasis is multi-factorial disease and excess fluoride consumption is one of the causal factors. In view of this, increase of fluoride in groundwater is reported in semiarid Deccan Volcanic Province (DVP), India. To understand the fluoride and urolithiasis association, present study was carried out in Karha river basin of DVP region. Three stages of data generation were adopted for present study such as procuring of medical records of urolithiasis, previous groundwater chemistry data and geochemical investigation of 50 groundwater samples from representative villages. Further, these variables were used for correlation analysis, temporal and spatial distribution to find out their relationships. Result shows medical records of hospitals indicating the gradual increase in urolithiasis is reported during drought situations. In temporal variation, annual fluoride concentration of groundwater and hot days are positively correlated with annual urolith patients as well as spatial study supports the same. In conclusion, present study highlights the relationship of urolith formation with number of hot days, groundwater electrical conductivity and fluoride. However, detailed biomedical study may lead towards understanding of fluoride- urolithiasis relationship.

Urolitiasis obstructiva en ovinos: Revisión

Urolithiasis is a disease process characterized by the presence of calculi or concretions in the urinary tract. Complex and multifactorial etiology, characterized by the formation of uroliths, that lodge in the urinary tract and care as they determine their obstruction, becoming known as urolithiasis. The first clinical signs in the animals with urolithiasis are related to pain. The objective of this work an update on the pathological picture of obstructive urolithiasis in sheep from addressing its history, etiology, epidemiology, pathogenesis, clinical signs, diagnosis, differential diagnosis, treatment, control and prevention.

Impact of hyperlipidaemia on intermediary metabolism, faecal microbial metabolites and urinary characteristics of lipoprotein lipase deficient vs. normal cats.

Findings in humans and rats indicate that hyperlipidaemia may be associated with enhanced endogenous oxalate (Ox) synthesis, which may be relevant for calcium oxalate (CaOx) urolith formation. Moreover, changes in lipid metabolism are proposed to negatively affect gut microbiota. This study aimed to investigate those potential interactions in hyperlipidaemic cats. Therefore, 10 normal control cats and seven lipoprotein lipase (LPL)-deficient cats were fed a low-fat diet for sevenweeks. During the last week of the study, cats were housed in metabolic cages to collect urine and faeces. Blood was taken on the last day of the study. The LPL-deficient cats had significantly higher serum triglyceride concentrations than normal cats, while lactate dehydrogenase (LDH) activity was not different. Urinary relative supersaturation with CaOx, urinary Ox, calcium, and citrate excretions, and urine pH did not differ between groups. Lower faecal acetic, propionic and total short-chain fatty acid concentrations were observed in the LPL-deficient cats. In conclusion, hyperlipidaemia does not appear to be a specific risk factor for CaOx urolith formation in cats. In contrast to results in rats, hyperlipidaemia was not accompanied by elevated serum LDH activity. As LDH can synthesise Ox from glycolate or other precursors, this might be one possible explanation for the similar urinary parameters in the LPL-deficient and normal cats. Non-diet-induced hyperlipidaemia was not associated with marked changes in faecal microbial metabolites, suggesting no differences in the composition of the intestinal microbiota.

Single layer cystotomy closure of excised porcine bladders with barbed versus smooth suture material.

To determine which of 2 suture materials would be superior in terms of closure time and leakage pressure in open single-layer cystotomy closure. Experimental study. Twenty-four freshly harvested porcine urinary bladders. A cystotomy was performed and the incision closed with a single layer simple continuous suture pattern with barbed (n = 12) or smooth (n = 12) suture. Time required for closure was measured. Each bladder was connected to a system for monitoring intraluminal pressure while inflated with saline until leakage occurred. Intraluminal pressure at time of initial leakage and leakage site were recorded. Two-sample t tests were used to compare maximum leakage pressure and closure time between the 2 groups. P < .05 was considered significant. All bladders were sutured successfully with no difference in mean closure time (barbed suture 296 ± 46 seconds; smooth suture 293 ± 26 seconds) (P = .821). There was no difference in mean leakage pressure of porcine urinary bladder incisions closed in a single layer with barbed suture (28.8 ± 10.4 mm Hg) compared with smooth suture (30.6 ± 8.8 mm Hg) (P = .642). Barbed suture provides comparable cystotomy repair to smooth suture, and no benefit to its use was identified in an open procedure. Barbed suture closure should be evaluated for adequate tensile strength in the presence of urine, satisfactory in vivo healing of cystotomies, and lack of long-term urolith formation in dogs and cats.

Dietary cation–anion difference may explain why ammonium urate nephrolithiasis occurs more frequently in common bottlenose dolphins ( ) under human care than in free-ranging common bottlenose dolphins

Ammonium urate nephrolithiasis frequently develops in common bottlenose dolphins (Tursiops truncatus) managed under human care but is rare in free-ranging common bottlenose dolphins. In other species, the dietary cation–anion difference (DCAD) can affect ammonium urate urolith formation by increasing proton excretion as ammonium ions. Therefore, differences in diet between the 2 dolphin populations could affect urolith formation, but the DCAD of most species consumed by free-ranging and managed dolphins is unknown. To compare the nutrient composition of diets consumed by free-ranging and managed bottlenose dolphins, samples (n = 5) of the 8 species of fish commonly consumed by free-ranging bottlenose dolphins in Sarasota Bay, FL, and the 7 species of fish and squid commonly fed to managed bottlenose dolphins were analyzed for nutrient content. Metabolizable energy was calculated using Atwater factors; the DCAD was calculated using 4 equations commonly used in people and animals that use different absorption coefficients. The nutrient composition of individual species was used to predict the DCAD of 2 model diets typically fed to managed common bottlenose dolphins and a model diet typically consumed by common bottlenose dolphins in Sarasota Bay. To mimic differences in postmortem handling of fish for the 2 populations of bottlenose dolphins, “free-ranging” samples were immediately frozen at −80°C and minimally thawed before analysis, whereas “managed” samples were frozen for 6 to 9 mo at −18°C and completely thawed. “Free-ranging” species contained more Ca and P and less Na and Cl than “managed” fish and squid species. As a consequence, the DCAD of both model managed dolphin diets obtained using 3 of the 4 equations was much more negative than the DCAD of the model free-ranging bottlenose dolphin diet (P < 0.05). The results imply that managed bottlenose dolphins must excrete more protons in urine than free-ranging bottlenose dolphins, which will promote nephrolith formation. The nutrient composition of the free-ranging bottlenose dolphin diet, determined for the first time here, can be used as a guide for feeding managed bottlenose dolphins, but research in vivo is warranted to determine whether adding more cations to the diet will prevent urolith formation in managed dolphins.

Dietary cation-anion difference may explain why ammonium urate nephrolithiasis occurs more frequently in common bottlenose dolphins () under human care than in free-ranging common bottlenose dolphins.

Ammonium urate nephrolithiasis frequently develops in common bottlenose dolphins () managed under human care but is rare in free-ranging common bottlenose dolphins. In other species, the dietary cation-anion difference (DCAD) can affect ammonium urate urolith formation by increasing proton excretion as ammonium ions. Therefore, differences in diet between the 2 dolphin populations could affect urolith formation, but the DCAD of most species consumed by free-ranging and managed dolphins is unknown. To compare the nutrient composition of diets consumed by free-ranging and managed bottlenose dolphins, samples ( = 5) of the 8 species of fish commonly consumed by free-ranging bottlenose dolphins in Sarasota Bay, FL, and the 7 species of fish and squid commonly fed to managed bottlenose dolphins were analyzed for nutrient content. Metabolizable energy was calculated using Atwater factors; the DCAD was calculated using 4 equations commonly used in people and animals that use different absorption coefficients. The nutrient composition of individual species was used to predict the DCAD of 2 model diets typically fed to managed common bottlenose dolphins and a model diet typically consumed by common bottlenose dolphins in Sarasota Bay. To mimic differences in postmortem handling of fish for the 2 populations of bottlenose dolphins, "free-ranging" samples were immediately frozen at -80°C and minimally thawed before analysis, whereas "managed" samples were frozen for 6 to 9 mo at -18°C and completely thawed. "Free-ranging" species contained more Ca and P and less Na and Cl than "managed" fish and squid species. As a consequence, the DCAD of both model managed dolphin diets obtained using 3 of the 4 equations was much more negative than the DCAD of the model free-ranging bottlenose dolphin diet ( < 0.05). The results imply that managed bottlenose dolphins must excrete more protons in urine than free-ranging bottlenose dolphins, which will promote nephrolith formation. The nutrient composition of the free-ranging bottlenose dolphin diet, determined for the first time here, can be used as a guide for feeding managed bottlenose dolphins, but research in vivo is warranted to determine whether adding more cations to the diet will prevent urolith formation in managed dolphins.

A frameshift mutation in MOCOS is associated with familial renal syndrome (xanthinuria) in Tyrolean Grey cattle.

BackgroundRenal syndromes are occasionally reported in domestic animals. Two identical twin Tyrolean Grey calves exhibited weight loss, skeletal abnormalities and delayed development associated with kidney abnormalities and formation of uroliths. These signs resembled inherited renal tubular dysplasia found in Japanese Black cattle which is associated with mutations in the claudin 16 gene. Despite demonstrating striking phenotypic similarities, no obvious presence of pathogenic variants of this candidate gene were found. Therefore further analysis was required to decipher the genetic etiology of the condition.ResultsThe family history of the cases suggested the possibility of an autosomal recessive inheritance. Homozygosity mapping combined with sequencing of the whole genome of one case detected two associated non-synonymous private coding variants: A homozygous missense variant in the uncharacterized KIAA2026 gene (g.39038055C > G; c.926C > G), located in a 15 Mb sized region of homozygosity on BTA 8; and a homozygous 1 bp deletion in the molybdenum cofactor sulfurase (MOCOS) gene (g.21222030delC; c.1881delG and c.1782delG), located in an 11 Mb region of homozygosity on BTA 24. Pathogenic variants in MOCOS have previously been associated with inherited metabolic syndromes and xanthinuria in different species including Japanese Black cattle. Genotyping of two additional clinically suspicious cases confirmed the association with the MOCOS variant, as both animals had a homozygous mutant genotype and did not show the variant KIAA2026 allele. The identified genomic deletion is predicted to be highly disruptive, creating a frameshift and premature termination of translation, resulting in severely truncated MOCOS proteins that lack two functionally essential domains. The variant MOCOS allele was absent from cattle of other breeds and approximately 4% carriers were detected among more than 1200 genotyped Tyrolean Grey cattle. Biochemical urolith analysis of one case revealed the presence of approximately 95% xanthine.ConclusionsThe identified MOCOS loss of function variant is highly likely to cause the renal syndrome in the affected animals. The results suggest that the phenotypic features of the renal syndrome were related to an early onset form of xanthinuria, which is highly likely to lead to the progressive defects. The identification of the candidate causative mutation thus enables selection against this pathogenic variant in Tyrolean Grey cattle.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0904-4) contains supplementary material, which is available to authorized users.

Feline Calcium Oxalate Urolithiasis: Risk factors and rational treatment approaches.

Uroliths occur commonly in the bladder and/or urethra of cats and can be lifethreatening if urethral obstruction occurs. Calcium oxalate accounts for 40-50% of urocystoliths and these stones are not amenable to medical dissolution; therefore, removal by surgery or minimally invasive techniques is required if uroliths must be treated. Medical protocols for prevention involve decreasing urine saturation for minerals that form uroliths. Formation of uroliths is not a disease, but rather a complication of several disorders. Some disorders can be identified and corrected (such as infection-induced struvite urolith formation); others can be identified but not corrected (such as idiopathic hypercalcemia). In most cats with calcium oxalate urolith formation the underlying etiopathogenesis is not known. A common denominator of all these disorders is that they can from time to time create oversaturation of urine with one or more crystal precursors, resulting in formation of crystals. In order to develop rational and effective approaches to treatment, abnormalities that promote urolith formation must be identified, with the goal of eliminating or modifying them. It is important, therefore, to understand several basic concepts associated with urolithiasis and the factors that promote urolith formation that may be modified with medical treatment; for example, the state of urinary saturation, modifiers of crystal formation, potential for multiple crystal types, and presence of bacterial infection or urinary obstruction.

Kinetics of calcium oxalate crystal formation in urine.

It is routinely observed that persons with increased urinary stone risk factors do not necessarily form uroliths. Furthermore, stone formers can present with urinalyses that do not reflect the clinical picture. We explain this discrepancy by differences in crystallization kinetics. In 1162 urines, crystallization of Ca-oxalate was induced according to the BONN-Risk-Index (BRI) method. The urine's relative light transmissivity (RLT) was recorded from 100% at start of titration to 95% due to nuclei formation and crystal growth. From the RLT changes, a measure of the thermodynamic inhibition threshold of crystal formation (BRI) and of crystal growth kinetics is derived ("turbidity slope" after crystallization onset). On average, subjects presenting with a low inhibition threshold, i.e., high BRI, also present significantly higher crystal growth rates compared with subjects in lower BRI classes. Only subjects in the highest BRI class show a lower growth rate than expected, probably due to a depletion of supersaturation by massive initial nucleation. With increasing thermodynamic risk of crystal formation (i.e., increasing BRI) due to an imbalance between inhibitors and promoters of crystal formation, an increase in the imbalance between inhibitors and promoters of crystal growth (i.e., increasing growth rate) is observed. Both lead to an increased urolith formation risk. Healthy subjects with increased BRI are an exception to this trend: their urine is thermodynamically prone to form stones, but they show a kinetic inhibition preventing nuclei from significant growth.

Ultrasonographic localization and mineral profile of urinary calculi in young and adult bovine

The study was conducted on 13 male bovine animals suffering from obstructive urolithiasis to evaluate the diagnostic approach, surgical outcome and mineral composition of uroliths. The animals were divided in two groups, Group I (n=8) of young animals and Group II (n=5) of adult animals. B-mode ultrasonography was done for locating the uroliths in penile urethra. All the animals were subjected to urethrotomy followed by ultrasonography at the suspected site of urolith lodgement. Ammonium chloride as urinary acidifier was given @ 50 mg/kg body weight orally for 60 days was found beneficial for preventing recurrence of uroliths. It was observed that urethra heals normally in three weeks if left unsutured and the majority of uroliths were present at tip of penis in Group I and in sigmoid flexure in Group II animals. Staphylococcus species were the most prevalent bacteria causing bovine urinary tract infections associated with urolithiasis in both groups. It was concluded that ultrasonography was efficient to localize uroliths in urethra in both groups of animals. On Fourier Transform Infrared Spectroscopy estimation, calcium carbonate, carbonate apatite in Group I whereas calcium carbonate in majority of Group II animals, were the most common types of minerals causing formation of uroliths.

Avaliação clínica, laboratorial e anatomopatológica do sistema urinário de ovinos confinados com ou sem suplementação de cloreto de amônio

Resumo: A acidificação urinária com cloreto de amônio (CA) é um método preventivo eficiente em urolitíase obstrutiva em ovinos. Os objetivos deste estudo com ovinos confinados, que receberam dieta concentrada com elevado teor proteico, foram: verificar o efeito da dieta sobre a formação de urólitos e o desenvolvimento da doença; analisar as características macroscópicas e histopatológicas do sistema urinário; relacionar os achados clínicos, laboratoriais e necroscópicos com a presença de urólitos. Utilizaram-se 60 ovinos machos: grupo CA (n=40), 400 mg/kg CA/dia, tratados via oral, por 42 dias consecutivos; grupo-controle (n=20), não tratado. Determinaram-se sete momentos de colheita de amostras com intervalos de sete dias, no total de 56 dias de confinamento. Encontraram-se microcálculos na pelve renal em cinco animais de ambos os grupos. As lesões renais microscópicas mais relevantes foram congestão vascular e necrose tubular. Concluiu-se que a dieta rica em concentrado provocou lesão renal em ambos os grupos, embora sem alterar a função renal, o que foi comprovado em testes pela ureia e creatinina séricas. O cloreto de amônio fornecido ao grupo CA não impediu a calculogênese, mas reduziu sua prevalência em relação ao grupo-controle. Os ovinos do grupo-controle tiveram maior comprometimento renal, pela alta incidência de cristalúria e pela necrose tubular, induzidas pelo consumo da dieta rica em grãos.

Urinalysis - A Diagnostic Factor for Urolithiasis and Prognostic Factor for its Recurrence in Young Ruminants

The experiment was a completely randomized block design with 6 groups awarded different treatments including 17 rams, 12 bucks and 113 calves. Animals clinically manifesting urolithiasis from field were merely screened as stone and non-stone formers. All replicates were run under different clinical situations with the objectives to screen calves as stone formers and non-stone formers and to ascertain recurrence risk due to residual fragments in future, and estimate urine biochemical analysis to ascertain a diagnostic factor for urolithiasis and prognostic factor for its recurrence that would help to evolve prophylactic protocol. Crystal formation indicated that urine was sufficiently saturated which support the formation and growth of uroliths. The, male calves showing numbers of crystals with a concomitant inflammatory process are at risk for calculi formation. Alterations in Urinary Calcium Phosphorous and Magnesium cannot be fixed as a diagnostic or prognostic value for detection of uroliths forming animals to a fear degree of accuracy. Urinalysis is simple and reliable test to confirm urinary tract disease and identify pathophysiology mechanisms associated with the underlying cause.

A Targeted Metabolomics Assay to Measure Eight Purines in the Diet of Common Bottlenose Dolphins, Tursiops truncatus.

Bottlenose dolphins managed under human care, human beings and Dalmatian dogs are prone to forming urate uroliths. Limiting dietary purine intake limits urate urolith formation in people and dogs because purines are metabolized to uric acid, which is excreted in urine. Managed dolphins develop ammonium urate nephroliths, whereas free-ranging dolphins do not. Free-ranging dolphins consume live fish, whereas managed dolphins consume different species that have been stored frozen and thawed. Differences in the purine content of fish consumed by dolphins under human care versus in the wild may be responsible for the difference in urolith prevalence. Commercially available purine assays measure only four purines, but reported changes in purines during frozen storage suggest that a wider range of metabolites should be measured when comparing fresh and stored fish. A method using high performance liquid chromatography with tandem mass spectrometry was developed to quantify eight purine metabolites in whole fish and squid commonly consumed by dolphins. The coefficient of variation within and among days was sometimes high for purines present in small amounts but was acceptable (≤ 25%) for guanine, hypoxanthine, and inosine, which were present in high concentrations. This expanded assay identified a total purine content up to 2.5 times greater than the total that would be quantified if only four purines were measured. Assuming additional purines are absorbed, these results suggest that additional purine metabolites should be measured to better understand the associated risk when fish or other purine-rich foods are consumed by people or animals prone to developing uroliths.

Risk factors for calcium carbonate urolithiasis in goats.

To identify demographic or signalment factors associated with calcium carbonate urolith formation in goats. Retrospective case series and case-control study. 354 goats with calcium carbonate uroliths (case animals) and 16,366 goats without urinary tract disease (control animals). Medical records of the Minnesota Urolith Center were reviewed to identify case goats for which samples were submitted between January 1, 1984, and December 31, 2012. Control goats evaluated at US veterinary teaching hospitals in the same time period were identified by searching Veterinary Medical Database records. Age, breed, sex, reproductive status, geographic location, season, and anatomic location of collected uroliths were analyzed to identify risk or protective factors associated with calcium carbonate urolithiasis. Nigerian dwarf goats had higher odds of developing calcium carbonate uroliths than did Pygmy goats (reference group). Several breeds had lower odds of this finding, compared with Pygmy goats; odds were lowest for mixed, Anglo-Nubian, and Toggenburg breeds. Breeds of African origin (Pygmy, Nigerian Dwarf, and Boer) comprised 146 of 275 (53%) case goats with data available. Goats of African descent had a higher risk of developing calcium carbonate uroliths than did goats of non-African descent (reference group). Males and neutered goats had higher odds of calcium carbonate urolithiasis, compared with females and sexually intact goats, respectively. Age category, geographic location, and season were associated with detection of calcium carbonate uroliths. Goats with calcium carbonate uroliths were typically neutered males, > 1 year of age, and of African descent. This study identified factors associated with calcium carbonate urolithiasis in goats; however, these associations do not allow conclusions regarding cause-and-effect relationships.

A review on urolithiasis in dogs and cats

Urolithiasis is a nutritional disease that affects domestic carnivores. Past and recent literature on urolithiasis was reviewed for information on anatomical occurrence, physiology of urine formation, prevalence, mineral composition, clinical signs, laboratory findings, dissolution therapy, surgery and prevention of urolithiasis. The acquired knowledge of complexed and multifaceted urolithiasis is a tremendous achievement towards the treatment and control of the disease. However, eradication of the disease is the most challenging as it requires total overhaul of all the factors that are responsible for the formation of uroliths.

Short term effects of increasing dietary salt concentrations on urine composition in healthy cats

High dietary salt (NaCl) concentrations are assumed to be beneficial in preventing the formation of calcium oxalate (CaOx) uroliths in cats, since increased water intake and urine volume have been observed subsequent to intake. In human beings, dietary NaCl restriction is recommended for the prevention of CaOx urolith formation, since high NaCl intake is associated with increased urinary Ca excretion. The aim of the present study was to clarify the role of dietary NaCl in the formation of CaOx uroliths in cats. Eight cats received four diets that differed in Na and Cl concentrations (0.38–1.43% Na and 0.56–2.52% Cl dry matter, DM). Each feeding period consisted of a 21 day adaptation period, followed by a 7 day sampling period for urine collection. Higher dietary NaCl concentrations were associated with increased urine volume and renal Na excretion. Urinary Ca concentration was constant, but renal Ca excretion increased from 0.62 to 1.05 mg/kg bodyweight (BW)/day with higher dietary NaCl concentrations (P ≤ 0.05). Urinary oxalate (Ox), citrate, P and K concentrations decreased when NaCl intake was high (P ≤ 0.05), and urinary pH was low in all groups (6.33–6.45; P > 0.05). Relative supersaturation of CaOx in the urine was unaffected by dietary NaCl concentrations. In conclusion, the present study demonstrated several beneficial effects of high dietary NaCl intake over a relatively short time period. In particular, urinary Ca concentration remained unchanged because of increased urine volume. Decreased urinary Ox concentrations might help to prevent the formation of CaOx uroliths, but this should be verified in future studies in diseased or predisposed cats.

The Bonn-Risk-Index for determination of the risk of urolith formation and other metabolic diseases

Scientific objectives The Bonn-Risk-Index (BRI) for the determination of the urinary stone formation risk is based on a crystallization test induced within a sample of native urine. The established method shows superior diagnostic sensitivity and specificity to other risk indices, derived from the urinary concentrations of some selected major urinary constituents considered to be indicators of the urine’s supersaturation with respect to the mineral phase formed by the patient. However, urinary supersaturation, the major thermodynamic driving force for crystal formation, is governed by all – organic and inorganic – components coexisting in the solution. In addition to the individual concentration of the components their mutual interactions also play an important role. Thus, BRI which “simulates” stone formation within whole urine meets much better the analytical demands to describe the “true supersaturation” than the costly determination of a couple of individual parameters. Indeed, minor constituents may take higher influence on an induced crystallisation process as one might expect from its urinary concentration. Urine composition reflects the influence of any of the patient’s metabolic processes – even of those analytically not directly accessible. Therefore, a change in urine composition leading to a variation in stone formation risk can indicate a change in the patient’s general metabolic state. Thus, BRI can also be used to monitor the general metabolic state by taking into account all urinary components, even unknown and difficult to access ones. In particular, changes in the calcium metabolisms could be detected as BRI is especially developed for the evaluation of the risk of formation of calcium stones. Clinical studies that systematically investigate the BRI, for example, in patients with bone diseases, like osteoporosis or Paget’s Disease, or in patients with diseases, which still lack a quantifiable progression parameter, should be run.

Relevance of dietary protein concentration and quality as risk factors for the formation of calcium oxalate stones in cats.

The role of dietary protein for the development of feline calcium oxalate (CaOx) uroliths has not been conclusively clarified. The present study evaluated the effects of a varying dietary protein concentration and quality on critical indices for the formation of CaOx uroliths. Three diets with a high protein quality (10-11 % greaves meal/diet) and a varying crude protein (CP) concentration (35, 44 and 57 % in DM) were compared. Additionally, the 57 % CP diet was compared with a fourth diet that had a similar CP concentration (55 % in DM), but a lower protein quality (34 % greaves meal/diet). The Ca and oxalate (Ox) concentrations were similar in all diets. A group of eight cats received the same diet at the same time. Each feeding period was divided into a 21 d adaptation period and a 7 d sampling period to collect urine. There were increases in urinary volume, urinary Ca concentrations, renal Ca and Ox excretion and urinary relative supersaturation (RSS) with CaOx with increasing dietary protein concentrations. Urinary pH ranged between 6·34 and 6·66 among all groups, with no unidirectional effect of dietary protein. Lower renal Ca excretion was observed when feeding the diet with the lower protein quality, however, the underlying mechanism needs further evaluation. In conclusion, although the observed higher urinary volume is beneficial, the increase in urinary Ca concentrations, renal Ca and Ox excretion and urinary RSS CaOx associated with a high-protein diet may be critical for the development of CaOx uroliths in cats.

Effects of potassium chloride and potassium bicarbonate in the diet on urinary pH and mineral excretion of adult cats

Low dietary K levels have been associated with increasing renal Ca excretion in humans, indicating a higher risk of calcium oxalate (CaOx) urolith formation. Therefore, the present study aimed to investigate whether dietary K also affects the urine composition of cats. A total of eight adult cats were fed diets containing 0·31 % native K and 0·50, 0·75 and 1·00 % K from KCl or KHCO₃ and were evaluated for the effects of dietary K. High dietary K levels were found to elevate urinary K concentrations (P<0·001). Renal Ca excretion was higher in cats fed the KCl diets than in those fed the KHCO₃ diets (P=0·026), while urinary oxalate concentrations were generally lower in cats fed the KCl diets and only dependent on dietary K levels in cats fed the KHCO₃ diets (P<0·05). Fasting urine pH increased with higher dietary K levels (P=0·022), reaching values of 6·38 (1·00 % KCl) and 7·65 (1·00 % KHCO₃). K retention was markedly negative after feeding the cats with the basal diet (-197 mg/d) and the 0·50 % KCl diet (-131 mg/d), while the cats tended to maintain their balance on being fed the highest-KCl diet (-23·3 mg/d). In contrast, K from KHCO₃ was more efficiently retained (P=0·018), with K retention being between -82·5 and 52·5 mg/d. In conclusion, the dietary inclusion of KHCO₃ instead of KCl as K source could be beneficial for the prevention of CaOx urolith formation in cats, since there is an association between a lower renal Ca excretion and a generally higher urine pH. The utilisation of K is distinctly influenced by the K salt, which may be especially practically relevant when using diets with low K levels.

Epidemiological evaluation of cystine urolithiasis in domestic ferrets (Mustela putorius furo): 70 cases (1992–2009)

To determine the prevalence of cystine uroliths in domestic ferrets with urolithiasis and determine whether age, breed, sex, reproductive status, anatomic location, and season are risk factors associated with cystine urolith formation. Retrospective cross-sectional case-control study. Records of 435 ferrets (Mustela putorius furo) with uroliths submitted for analyses between 1992 and 2009, of which 70 were cystine uroliths. Specific descriptive information was obtained about each ferret to determine whether specific risk factors were associated with the development of cystine uroliths. Cystine uroliths comprised 70 of the 435 (16%) uroliths. Cystine uroliths were more common in male (n = 54) than in female (16) ferrets. All cystine uroliths were retrieved from the lower portion of the urinary tract (bladder and urethra [n = 67]) or were voided (3); none of the uroliths were retrieved from the upper portion of the urinary tract (kidney and ureters). Awareness of the prevalence of cystine uroliths along with knowledge of etiologic, demographic, and environmental risk and protective factors for urolithiasis may facilitate development of surveillance strategies that result in earlier detection of cystinuria. Genetic factors associated with this disease have not yet been reported in ferrets, but a familial pattern of inheritance determined to be a major underlying factor in cystine urolithiasis in dogs and humans suggests that this may be a factor in ferrets and that the parent stock of ferrets in the present study may have been inbred.