Application of novel burst wave lithotripsy and ultrasonic propulsion technology for the treatment of ureteral calculi in a bottlenose dolphin (Tursiops truncatus) and renal calculi in a harbor seal (Phoca vitulina).

Marine mammals may develop kidney stones, which can be challenging to treat. We describe burst wave lithotripsy (BWL) and ultrasonic propulsion to treat ureteral calculi in a 48-year-old female bottlenose dolphin (Tursiops truncatus) and to reduce renal stone burden in a 23-year-old male harbor seal (Phoca vitulina). BWL and ultrasonic propulsion were delivered transcutaneously in sinusoidal ultrasound bursts to fragment and reposition stones. Targeting and monitoring were performed with real-time imaging integrated within the BWL system. Four dolphin stones were obtained and fragmented ex vivo. The dolphin case received a 10-min and a 20-min BWL treatment conducted approximately 24 h apart to treat two 8-10 mm partially obstructing right mid-ureteral stones, using oral sedation alone. For the harbor seal, while under general anesthesia, retrograde ureteroscopy attempts were unsuccessful because of ureteral tortuosity, and a 30-min BWL treatment was targeted on one 10-mm right kidney stone cluster. All 4 stones fragmented completely to < 2-mm fragments in < 20 min ex vivo. In the dolphin case, the ureteral stones appeared to fragment, spread apart, and move with ultrasonic propulsion. On post-treatment day 1, the ureteral calculi fragments shifted caudally reaching the ureteral orifice on day 9. On day 10, the calculi fragments passed, and the hydroureter resolved. In the harbor seal, the stone cluster was observed to fragment and was not visible on the post-operative computed tomography scan. The seal had gross hematuria and a day of behavior indicating stone passage but overall, an uneventful recovery. BWL and ultrasonic propulsion successfully relieved ureteral stone obstruction in a geriatric dolphin and reduced renal stone burden in a geriatric harbor seal.

Nephrolithiasis in a giant Pacific octopus Enteroctopus dofleini.

Managed care of cephalopods can be complicated by numerous factors including infectious and non-infectious disease, environmental stressors, and anatomic and physiological changes associated with senescence. The current report describes a unique case of nephrolithiasis in a senescent, >2 yr old female Pacific octopus Enteroctopus dofleini housed in a public aquarium. Clinical signs included generalized external pallor, inappetence progressing to anorexia, lethargy, and a slow healing mantle abrasion over a period of a year. Due to the animal's declining condition, humane euthanasia was elected. At necropsy, multiple, small, approximately 1-5 mm diameter crystalline deposits were reported throughout all sections of the renal appendages. Histopathology identified a large crystal expanding and rupturing a focal tubule, causing necrosis, ulceration, and hemocytic infiltration. Crystalline stone analysis revealed that the nephrolith was composed of 100% ammonium acid urate. Additional changes to the digestive gland included marked atrophy with fibrosis correlated to the animal's history of hyporexia/anorexia secondary to senescence. To our knowledge, this is the first report of nephrolithiasis in E. dofleini.

The use of endoscopy-assisted nephrolithotomy for unilateral nephrolith removal in a rabbit (Oryctolagus cuniculus).

A 3-year-old spayed female rabbit (Oryctolagus cuniculus) was referred with mineralizations in the left kidney. Despite medical management, 8 months after the initial examination, a 5.3-mm obstructive nephrolith with dilatation of the renal diverticuli was observed with abdominal ultrasonography. Surgical removal by endoscopy-assisted nephrolithotomy was completed. A flexible endoscope was introduced into the renal pelvis through a puncture incision in the lateral aspect of the kidney. The nephrolith was removed with endoscopic grasping forceps through the same orifice and the renal pelvis and diverticula were flushed to extract the smaller mineralized particles. The nephrotomy site was closed and the kidney was sutured to the abdominal wall. The rabbit recovered uneventfully. Six months after surgery, a non-obstructive stone was identified; however, 2 years later the rabbit remains asymptomatic. To the authors' knowledge, this is the first report on the use of endoscopy-assisted nephrolithotomy to extract a complicated nephrolith in a rabbit.

L'utilisation de la néphrolithotomie assistée par endoscopie pour l'élimination unilatérale des néphrolithes chez un lapin ( Oryctolagus cuniculus ). Une lapine stérilisée de 3 ans (Oryctolagus cuniculus) a été référée avec des minéralisations dans le rein gauche. Malgré la prise en charge médicale, 8 mois après l'examen initial, un néphrolithe obstructif de 5,3 mm avec dilatation des diverticules rénaux a été observé à l'échographie abdominale. L'ablation chirurgicale par néphrolithotomie assistée par endoscopie a été réalisée. Un endoscope flexible a été introduit dans le pelvis rénal par une incision de ponction dans la face latérale du rein. Le néphrolithe a été retiré avec une pince à préhension endoscopique par le même orifice et le bassinet et les diverticules rénaux ont été rincés pour extraire les plus petites particules minéralisées. Le site de néphrotomie a été fermé et le rein a été suturé à la paroi abdominale. Le lapin a récupéré sans incident. Six mois après la chirurgie, une pierre non obstructive a été identifiée; cependant, 2 ans plus tard, le lapin reste asymptomatique. À la connaissance des auteurs, il s'agit du premier rapport sur l'utilisation de la néphrolithotomie assistée par endoscopie pour extraire un néphrolithe compliqué chez un lapin.(Traduit par Dr Serge Messier).

Ureteropyeloscopic removal of a nephrolith from a 19 year old Hanoverian gelding.

OBJECTIVE: To describe the ureteropyeloscopic removal of a nephrolith in a horse. ANIMALS: A 19 year old Hanoverian gelding with history of urolithiasis requiring surgical intervention. STUDY DESIGN: Case report METHODS: The horse presented with signs of abdominal straining and stranguria. A proximal urethral calculus was palpable externally within the perineal urethra. Perineal urethrostomy (PU) at the location of the urethral calculi was performed to remove the urethral obstruction. Left nephrolithiasis was then treated by endoscopic retrieval, inserting the endoscope through the PU. The procedures were performed over 2 consecutive days, with the horse standing and sedated. Medical therapy included antimicrobial and anti-inflammatory treatment. RESULTS: The ureteropyeloscopic removal of a nephrolith from the left renal pelvis was completed. No complications were appreciated following the procedure, and the horse was able to return to athletic activity within 2 weeks. The horse had no further clinical signs referable to urinary dysfunction 7 months later. CONCLUSION: Ureteropyeloscopic removal of a nephrolith from the renal pelvis is technically feasible in the equine patient and preserves function of the affected kidney. The availability of a treatment that maintains renal function is a distinct benefit over unilateral nephrectomy, particularly when treating a condition that frequently involves both kidneys.

Dietary effects on urinary physicochemistry in Navy bottlenose dolphins (Tursiops truncatus) for the prevention of ammonium urate kidney stones.

Bottlenose dolphins are susceptible to developing ammonium urate (NH4U) kidney stones. The current study was designed to test the hypothesis that diet influences the urinary physicochemistry risk factors associated with nephrolithiasis in dolphins. A comprehensive nutrient analysis was performed revealing that the baseline diet (BD) commonly fed to dolphins under professional care had a greater purine content and a more negative dietary cation-anion difference (DCAD) when compared with a model diet consumed by free-ranging dolphins. A modified diet (MD) was formulated to include free-ranging diet fish species and achieve a more positive DCAD. The BD had a more negative DCAD (-52 mEq/Mcal metabolizable energy) when compared with the MD (+51 mEq/Mcal ME), which more closely approximated the DCAD of the free-ranging model diet (+152 mEq/Mcal ME). Six dolphins (with stones) were fed the BD followed by the MD for a minimum of 4 wk. At the end of each feeding trial, a 6-h continuous urine collection was performed to compare urine parameters of dolphins fed the BD versus MD. Dolphins consuming the MD demonstrated a significant decrease in urinary ammonium, net acid excretion, saturation index of ammonium urate, and phosphorous, and a significant increase in urinary citrate and net gastrointestinal (GI) alkali absorption, as compared with urine parameters assessed when fed the BD. Increasing the proportion of free-ranging diet fish species and optimizing the DCAD positively influenced some of the risk factors believed to be associated with NH4U kidney stone development in bottlenose dolphins under professional care.

Management of nephrolithiasis by pyelotomy and pyeloscopy in an Asian small-clawed otter (Aonyx cinereus).

CASE DESCRIPTION: A captive adult sexually intact female Asian small-clawed otter (Aonyx cinereus) was evaluated because of diarrhea and signs of abdominal discomfort on arrival at the quarantine area of a zoological park. CLINICAL FINDINGS: Radiographic and ultrasonographic examinations revealed the presence of a large nephrolith in the left kidney. Mild nephrolithiasis was detected in the right kidney. Results of hematologic and serum biochemical analyses were within references intervals. Intravenous pyelography was used for functional assessment of the urinary system and revealed normal renal excretory function bilaterally. TREATMENT AND OUTCOME: Unilateral (left-sided) pyelotomy was selected as a treatment option to preserve maximal functional renal tissue. Pyeloscopy was successfully used for detection of some small nephroliths that were not removed by repeated flushing of the renal pelvis. Surgical treatment of the right kidney was not considered necessary. The otter recovered fully from anesthesia and surgery. Renal function was considered normal when assessed at 3 and 7 days and at 1 and 12 months after surgery. CLINICAL RELEVANCE: To the authors' knowledge, pyelonephrotomy in otters has not been reported and may be considered as a potential surgical solution for nephrolithiasis. Pyeloscopy allowed the identification of small uroliths that were not removed by repeated flushing of the left renal pelvis following removal of the large nephroliths.

Endoscopic nephrolithotomy for the removal of complicated nephroliths in dogs and cats: 16 kidneys in 12 patients (2005-2017).

OBJECTIVE: To describe techniques and outcomes for dogs and cats undergoing endoscopic nephrolithotomy (ENL) for the removal of complicated nephroliths. ANIMALS: 11 dogs and 1 cat (n = 16 renal units) with complicated nephroliths that underwent ENL via a surgically assisted ENL approach (12 renal units) or a percutaneous nephrolithotomy approach (4 renal units) between December 2005 and June 2017. PROCEDURES: Data were obtained from the medical records regarding preoperative, operative, and postoperative findings. Follow-up information on complications and outcomes was also collected. RESULTS: Indications for nephrolith removal included massive calculi displacing parenchyma (n = 7), recurrent urinary tract infections (5), and ureteral outflow obstruction (4). Median nephrolith diameter was 2.5 cm (range, 0.5 to 5.7 cm). Nephrolith composition differed among patients; calcium oxalate was the most common type (n = 7 [including 2 mixed nephroliths containing ≥ 60% calcium oxalate]). Following ENL (median duration, 180 minutes), 15 of 16 renal units were completely nephrolith free. Procedure-related complications included renal puncture-associated hemorrhage requiring a blood transfusion (n = 1), renal capsule tear (1), and ureteral puncture (1); all were managed without adverse consequence. Five of 12 patients remained alive at the final follow-up (median, 557 days after ENL), and none died from the procedure. CONCLUSIONS AND CLINICAL RELEVANCE: ENL as performed was safe and effective in removing complicated nephroliths in a renal-sparing manner for the patients in this study. This procedure requires technical training and could be considered for the treatment of complicated nephrolithiasis in dogs and possibly cats.

Comparison of porous and nano zinc oxide for replacing high-dose dietary regular zinc oxide in weaning piglets.

The aim of this study was to compare the effect of dietary supplementation with low dose of porous and nano zinc oxide (ZnO) on weaning piglets, and to evaluate the possibility of using them as an alternative to high dose of regular ZnO. Piglets were randomly allocated into four treatment groups fed with four diets: (1) basal diet (NC), (2) NC+ 3000 mg/kg ZnO (PC), (3) NC + 500 mg/kg porous ZnO (HiZ) and (4) NC + 500 mg/kg nano ZnO (ZNP). The result showed that piglets in HiZ group had less diarrhea than ZNP group (P < 0.05). Besides, there was no significant difference between PC, HiZ and ZNP groups in terms of serum malondialdeyhde (MDA) concentration and glutathione peroxidase (GSH-Px) activity (P > 0.05). Analysis of trace metal elements revealed that piglets fed with high dose of regular ZnO had the highest Zn level in kidney (P < 0.05), which may induce kidney stone formation. Additionally, a decrease in ileal crypt depth was observed in PC, HiZ and ZNP group, suggesting an effective protection against intestinal injury. Results of mRNA analysis in intestine showed that ZNP supplementation had better effects on up-regulated trefoil factor 3 (TFF3) and nuclear factor erythroid 2-related factor 2 (Nrf2) levels in duodenum and jejunum than HiZ did (P < 0.05), implying that nano ZnO may possess higher anti-inflammatory capacity than porous ZnO. In conclusion, dietary supplementation with low dose of porous and nano ZnO had similar (even better) effect on improving growth performance and intestinal morphology, reducing diarrhea and intestinal inflammatory as high dose of regular ZnO in weaning piglets. Compared with nano ZnO, porous ZnO had better performance on reducing diarrhea but less effect on up-regulation of intestinal TFF3 and Nrf2.

Serum concentrations of symmetric dimethylarginine and creatinine in cats with kidney stones.

Serum concentrations of symmetric dimethylarginine (SDMA) correlate with renal function in cats and SDMA has been shown to be a more reliable and earlier marker for chronic kidney disease (CKD) compared with serum creatinine (Cr). Calcium oxalate uroliths tend to develop in mid-to-older aged cats and kidney stones may cause a reduction in renal function with increased SDMA, but normal serum Cr. The purpose of this retrospective study was to determine if cats with kidney stones had increased serum SDMA concentrations, and whether SDMA increased earlier than serum creatinine concentrations. Cats in the colony with kidney stones diagnosed between August 2010 and December 2015 (n = 43) were compared with healthy geriatric cats (n = 21) without kidney stones. Serum SDMA concentrations were determined by liquid chromatography-mass spectrometry and serum Cr concentrations were determined by enzymatic colorimetry. Cats with kidney stones were diagnosed antemortem by radiographic imaging (n = 12) or by postmortem necropsy (n = 31). Retrospectively, serum SDMA was found to be increased above the upper reference limit in 39 of 43 cats with kidney stones. Serum Cr was increased above the upper reference limit in 18 of 43 cats; 6 of these 18 cats had terminal azotemia only. The mean time that serum SDMA was increased before serum Cr was increased was 26.9 months (range 0 to 60 months). Kidney stones were composed of calcium oxalate in 30 of 34 cats. The lifespan for cats with kidney stones (mean, 12.5 years; range, 6.1 to 18.1 years) was shorter (P < 0.001) than for control cats (mean, 15.2 years; range, 13.0 to 17.2 years), suggesting that non-obstructive kidney stones have an effect on mortality rate or rate of CKD progression. In conclusion, if SDMA concentrations are elevated in mid-to-older aged cats, further imaging studies are warranted to check for the presence of kidney stones.

Solubility of ammonium acid urate nephroliths from bottlenose dolphins (Tursiops truncatus).

Nephrolithiasis has been identified in managed populations of bottlenose dolphins (Tursiops truncatus); most of these nephroliths are composed of 100% ammonium acid urate (AAU). Several therapies are being investigated to treat and prevent nephrolithiasis in dolphins including the alkalization of urine for dissolution of nephroliths. This study evaluates the solubility of AAU nephroliths in a phosphate buffer, pH range 6.0-8.0, and in a carbonate-bicarbonate buffer, pH range 9.0-10.8. AAU nephroliths were obtained from six dolphins and solubility studies were conducted using reverse-phase high performance liquid chromatography with ultraviolet detection at 290 nm. AAU nephroliths were much more soluble in a carbonate-bicarbonate buffer, pH range 9.0-10.8 compared to phosphate buffer pH range 6.0-8.0. In the pH range 6.0-8.0, the solubility was 45% lower in potassium phosphate buffer compared to sodium phosphate buffer. When citrate was used along with phosphate in the same pH range, the solubility was improved by 13%. At pH 7 and pH 8, 150 mM ionic strength buffer was optimum for dissolution. In summary, adjustment of urinary pH alone does not appear to be a useful way to treat AAU stones in bottlenose dolphins. Better understanding of the pathophysiology of AAU nephrolithiasis in dolphins is needed to optimize kidney stone prevention and treatment.

Lateral approach to nephrotomy in the management of unilateral renal calculi in a rabbit (Oryctolagus cuniculus).

CASE DESCRIPTION: A 5-year-old 2.23-kg (4.91-lb) spayed female Lop rabbit (Oryctolagus cuniculus) was evaluated because of a history of lethargy, polyuria, and polydipsia of 1 month's duration. The referring veterinarian made a presumptive diagnosis of hypercalcemia of unknown etiology on the basis of a plasma total calcium concentration of 14.0 mg/dL. CLINICAL FINDINGS: Physical examination findings were unremarkable. Hematologic and plasma biochemical analysis revealed nonregenerative, normocytic, normochromic anemia (PCV, 28%) with heteropenia (23%; 1,334 heterophils/mL) and a total plasma calcium concentration of 16 mg/dL. Radiographic and ultrasonographic examination revealed radiodense and hyperechoic structures in both renal pelves and right unilateral nephrolithiasis. TREATMENT AND OUTCOME: Nephrotomy was performed via laparotomy with a right lateral approach. A nephrolith composed of calcium carbonate and carbonate apatite was removed from the right renal pelvis. The rabbit's plasma tested positive for antibodies against Encephalitozoon cuniculi by means of an indirect immunofluorescence assay, and fenbendazole (20 mg/kg [9.1 mg/lb], p.o., q 24 h) was administered for 28 days. Although plasma calcium concentration was not substantially decreased after treatment (values were 14.1 and 15.1 mg/dL 1 week and 3 months after surgery, respectively), the patient did not have clinical signs of hypercalcemia and died of unrelated causes approximately 1 year after surgery. CLINICAL RELEVANCE: To the authors' knowledge, this is the first report of a nephrotomy performed in a rabbit via a lateral abdominal approach. This approach allowed easy location of the kidney and also reduced manipulation, thus decreasing the risk of damaging the abdominal viscera and potentially decreasing postoperative pain.

Urolitíase em 76 cães / Urolithiasis in 76 dogs

Entre janeiro de 1990 e dezembro de 2010 foram necropsiados 4.872 cães no Laboratório de Patologia Veterinária da Universidade Federal de Santa Maria (LPV-UFSM). Destes, 76 (1,6%) apresentaram urólitos em algum local do sistema urinário. O perfil epidemiológico dos cães afetados demonstrou o predomínio de machos (64,5%), adultos (52,6%) e com raça definida (56,6%). Sinais clínicos indicativos de urolitíase foram reportados em 30,3% dos casos e consistiram principalmente de hematúria, anúria, disúria e incontinência urinária. Os urólitos tiveram localização única ou múltipla e os locais anatômicos mais frequentemente acometimentos, em ordem decrescente de frequência, foram: bexiga, rim e uretra. Urolitíase ureteral não foi observada. Lesões secundárias à urolitíase foram observadas em aproximadamente 40% dos cães afetados; as mais prevalentes, em ordem decrescente de frequência, foram: cistite, obstrução uretral, hidroureter, hidronefrose, ruptura vesical (com uroperitônio) e pielonefrite. Em 25% dos cães afetados ocorreu morte espontânea ou eutanásia decorrente das lesões secundárias à urolitíase. Lesões extra-renais de uremia foram observadas em 11,8% dos casos.

From January 1990 to December 2010, 4,872 dogs were necropsied at the Laboratório de Patologia Veterinária, Universidade Federal de Santa Maria. Seventy six dogs (1.6%) had uroliths along the urinary tract. The epidemiological profile of the affected dogs showed predominance of males (64.5%); adults (52.6%); and pure breeds (56.6%). Clinical signs suggestive of urolithiasis were reported in 30.3% of the dogs and consisted mainly of hematuria, anuria, dysuria and urinary incontinency. The uroliths were found in one or more anatomical sites, and the main affected ones (in descending order) were urinary bladder, kidney, and urethra. Ureteral urolithiasis was not observed. Secondary lesions to urolithiasis were found in about 40% of the cases. The most prevalent (in descending order) were cystitis, urethral obstruction, hydroureter, hydronephrosis, urinary bladder rupture (with uroperitoneum), and pyelonephritis. In 25% of the affected dogs, spontaneous death occurred or euthanasia was performed due to the secondary lesions of urolithiasis. Extra-renal lesions of uremia were found in 11.8% of the cases.

Impact of a high-phosphorus diet on the sonographic and CT appearance of kidneys in degus, and possible concurrence with dental problems.

The main aim of this study was to investigate the impact of pelleted diet of different mineral composition on the sonographic and CT appearance of kidneys in degus (Octodon degus). A total of 35 animals were randomly divided into five groups, fed diets containing different calcium and phosphorus contents (13.5 g/kg calcium and 6.3 g/kg phosphorus, or 9.1 g/kg calcium and 9.5 g/kg phosphorus) and given different amounts of exposure to UV light. Endoscopic examination of the oral cavity as well as renal ultrasonography and CT was performed four times at four-month intervals throughout the study. After 14 months of feeding an experimental diet, all degus were euthanased and subsequently all kidneys were collected for histopathological examination. Animals fed a diet with high dietary phosphate and improper calcium to phosphorus ratio showed severe nephrocalcinosis. Ultrasonographic and CT kidney abnormalities presented as hyperechogenicity and hyperdensity (interpreted as nephrocalcinosis), respectively. The most striking changes were seen at the corticomedullary zone. Ultrasonography and CT correlated in all cases with histopathological findings. Dental disease developed quickly in groups fed diets with an improper calcium and phosphorus content, with obvious apical and coronal elongation of all the teeth. A possible influence of UV light access could not be proved in this study.

A case of renal oxalosis in a 3-month-old cat raised under controlled conditions.

The kidneys of a 3-month-old female cat were examined. The cat which had been raised under controlled conditions with no history of any poisoning showed progressive weight loss with increases in blood BUN and creatinine concentrations. At necropsy, both kidneys were firm in consistency with formation of focal scars. Histopathologically, widespread deposition of crystals was observed in the renal tubules (in both dilated lumina and degenerative epithelia) accompanying mild interstitial fibrosis with lymphocyte infiltration. The crystals were colorless or basophilic on the hematoxilin and eosin-stained section and could be visualized with polarized light as doubly fractile crystals. The crystals were identified as calcium oxalate crystals by histochemical examinations using von Kossa stain and alizarin red S stain under different conditions and by ultrastructural examination. Judging from the above-mentioned findings, the present renal lesion detected in an infant cat was diagnosed as renal oxalosis which was suspected to be hereditary in nature.

Comparative sonographic appearance of nephroliths and associated acoustic shadowing artifacts in conventional vs. spatial compound imaging.

Spatial compound sonography improves visualization of tissue details and allows clearer delineation of structural margins. Improved image clarity is due to reduced speckling artifact; however, other types of acoustic shadowing artifacts may be unchanged or variably altered when conventional and spatial compound sonographic images are compared. Because intrarenal distal shadowing artifacts in conventional sonographic images are oftentimes the first or only evidence that a nephroliths is present, we compared the appearance and associated artifacts of nephroliths examined with both imaging modes. Consensus evaluation by two evaluators confirmed differences in appearance of nephroliths based on imaging mode. Nephroliths with conventional imaging mode were less hyperechoic and had better margin delineation while nephroliths were more hyperechoic and had less distinct margins with spatial compound imaging mode. Distal acoustic shadowing artifacts were present in 43% of spatial compound imaging mode vs. 86% of conventional imaging mode. When present in both imaging modes, intensity of these artifacts was weaker and the distance traveled was shorter in spatial compound imaging mode. Multiple diverging acoustic shadowing artifacts originating from a single source, the nephroliths were occasionally noted in spatial compound but not conventional imaging mode. These results demonstrate that the absence of distal acoustic shadowing cannot be used to exclude the presence of a nephrolith in dogs and cats. Optimal diagnosis of nephroliths, margin delineation, and visualization of the distal renal parenchyma requires paired radiography and sonography, and alternating between sonographic imaging modes is therefore suggested.

Oxalate nephropathy in a laboratory colony of common marmoset monkeys (Callithrix jacchus) following the ingestion of Eucalyptus viminalis.

Seven common marmoset monkeys (Callithrix jacchus) from a laboratory colony of 17 died over a period of eight months. Death of six of these monkeys was attributed to kidney failure from an oxalate-induced nephropathy. The epidemiology of this outbreak suggested an exogenous source and there was strong evidence that the source was bark and leaves from an Eucalyptus viminalis tree. Branches of this tree were introduced one month before the first death. The branches were removed one month after deaths commenced, but deaths continued for another five months. Urinalysis of all surviving marmosets at 80 and 122 days after initial contact with the E viminalis branches suggested that these monkeys had renal impairment. In the cases described here, the eating behaviour of common marmosets apparently exposed the animals to toxic levels of oxalate in the bark and leaves of an E viminalis tree.

Renal calculi in wild Eurasian otters (Lutra lutra) in England.

Macroscopic renal calculi were seen in 50 of 492 (10.2 per cent) wild Eurasian otters found dead in England from 1988 to 2007. Forty-eight adults and two subadults were affected. Calculi were present in 15.7 per cent (31 of 197) of adult males and 12.7 per cent (17 of 134) of adult females. There was an increase in prevalence in the study population over time; no calculi were found in 73 otters examined between 1988 and 1996, but in most subsequent years they were observed with increased frequency. Calculi occurred in both kidneys but were more common in the right kidney. They varied greatly in shape and size; larger calculi were mostly seen in the calyces while the smallest ones were commonly found in the renal medulla. Calculi from 45 cases were examined by x-ray diffraction analysis; in 43 (96 per cent), they were composed solely of ammonium acid urate. Affected otters had heavier adrenal glands relative to their body size than unaffected otters (P<0.001). There was no significant association between body condition index and the presence of calculi (P>0.05). Many otters had fresh bite wounds consistent with intraspecific aggression. The proportion bitten increased over time and this coincided with the increased prevalence of renal calculi.

Melamine-related kidney stones and renal toxicity.

Several well-documented outbreaks of melamine poisoning have occurred in both animals and humans during the past 7 years, which led to the identification of melamine and cyanuric acid as nephrotoxins. This Review provides an overview of the known experimental and observational data (including toxicology, epidemiology, and pathology) concerning melamine contamination of foodstuffs, both alone and in combination with cyanuric acid. The various renal effects of ingestion of these compounds in both animals and humans are described, and a hypothesis on the mechanism of formation of melamine-based kidney stones is presented. Finally, the public health measures taken in the wake of the melamine contamination events are discussed.

Melamine residues in eggs of laying hens exposed to melamine-contaminated feed.

An experiment was carried out to determine melamine residual levels in eggs by feeding laying hens 200 or 1,000 mg of melamine/kg of diet. Each diet was offered in 3 replicate cages (10 laying hens/cage) from d 1 to 29, followed by a 9-d feeding of a withdrawal diet that contained no melamine. Two eggs were collected from each replicate cage each day for the determination of residual melamine levels after 1 d of feeding. The feeding of melamine resulted in a fast accumulation of melamine in eggs within 3 to 4 d, then maintained 2.00 to 3.88 mg/kg for 200 mg of melamine/kg of diet and 11.09 to 16.46 mg/kg for 1,000 mg of melamine/kg of diet. A withdrawal period of 4.0 d for 1,000 mg of melamine/kg of diet was required based on tolerance values established by the World Health Organization and no withdrawal period was required for 200 mg of melamine/kg of diet.