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.

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.

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).

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.

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.

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.

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.

Feline porphyria associated with anemia, severe hepatic disease, and renal calculi.

A 13-year-old, neutered male domestic cat presented with signs of weight loss, anemia, and hepatomegaly. Pathognomonic signs of porphyria were identified. Charcoal-like renal calculi and severe liver changes were observed, neither of which has been previously reported in association with feline porphyria.

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.

Defective skeletogenesis with kidney stone formation in dwarf zebrafish mutant for trpm7.

Development of the adult form requires coordinated growth and patterning of multiple traits in response to local gene activity as well as to global endocrine and physiological effectors. An excellent example of such coordination is the skeleton. Skeletal development depends on the differentiation and morphogenesis of multiple cell types to generate elements with distinct forms and functions throughout the body. We show that zebrafish touchtone/nutria mutants exhibit severe growth retardation and gross alterations in skeletal development in addition to embryonic melanophore and touch-response defects. These alterations include accelerated endochondral ossification but delayed intramembranous ossification, as well as skeletal deformities. We show that the touchtone/nutria phenotype results from mutations in trpm7, which encodes a transient receptor potential (TRP) family member that functions as both a cation channel and kinase. We find trpm7 expression in the mesonephric kidney and show that mutants develop kidney stones, indicating renal dysfunction. These results identify a requirement for trpm7 in growth and skeletogenesis and highlight the potential of forward genetic approaches to uncover physiological mechanisms contributing to the development of adult form.

Radiographic signs of renal disease in rabbits.

The radiological features of 65 rabbits with suspected renal disease are reviewed. The radiological features included a generalised increase in bone opacity (osteosclerosis), renomegaly, nephroliths, ureteroliths and soft tissue mineralisation. One or more of these changes were present on radiographs of 57 of the 65 rabbits. Renal disease was suspected because of the clinical signs and the presence of kidney stones and/or high blood concentrations of urea and creatinine. Significant renal disease was confirmed in 14 cases that were examined postmortem. Blood urea and creatinine concentrations were measured in 47 cases but not all the rabbits had high levels of both. Blood calcium concentration was high in 33 of the 38 rabbits in which it was measured. Serum phosphate was high in 17 and low in five of 34 rabbits in which it was measured. Hyperphosphataemia was associated with generalised osteosclerosis and aortic calcification. Rabbits with osteosclerosis were thin, depressed and unwilling to move. Thirty-eight of 41 rabbits that were tested were seropositive for antibodies to Encephalitozoon cuniculi. Histological lesions suggestive of E cuniculi infection were found in all 13 cases that were examined postmortem, although the organisms were visible in only one case.

Urate nephrolithiasis in a northern elephant seal (Mirounga angustirostris) and a California sea lion (Zalophus californianus).

Nephrolithiasis has rarely been reported in marine mammals. During 2004 and 2005, two cases of nephrolithiasis were diagnosed during routine necropsy examination, one in a northern elephant seal (Mirounga angustirostris) and one in a California sea lion (Zalophus californianus). Nephroliths were found throughout both kidneys during necropsy examination, varying in size from 1-10 mm in diameter in the northern elephant seal and from 1-15 mm in diameter in the California sea lion. Necropsy and histopathology revealed nephroliths in association with renal pelvic dilation and pyelonephritis in both animals. In addition, hydronephrosis was noted in the sea lion. Nephroliths were composed of uric acid and ammonium urate in the northern elephant seal and of ammonium urate in the California sea lion. The underlying disease leading to nephrolith formation was not determined; however, it is hypothesized that unknown metabolic derangements due to morphologic or physiologic differences may have played a role. This is the first report of urate nephrolithiasis in the California sea lion and northern elephant seal.

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.

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.

Subclinical renal oxalosis in wild-caught Japanese macaques (Macaca fuscata).

Various degrees of crystal deposition were found in the kidneys of 12 out of 59 Japanese macaques (Macaca fuscata) caught in the wild in Gifu, Japan. The needle- or rod-shaped crystals, which were radially arranged and occurred in the lumen and epithelium of the renal (mainly the proximal) tubules, were birefringent under polarized light. They stained with alizarin red S at a pH of 7.0 but not 4.2, and were identified as calcium oxalate. The morphological features of the renal lesions were similar to those previously reported in oxalate poisoning, and it was believed that the macaques ingested the oxalate in plants.

Crystalline composition of equine urinary calculi.

X-ray diffraction crystallography was used to determine the crystalline composition of 18 equine urinary calculi, including stones originating in the kidney, bladder and urethra. Calcium carbonate in the form of calcite was found to be the major component in all calculi examined. Other components commonly found included weddellite and substituted vaterite. Urine deposits from a number of normal horses were also examined. The significance of these findings, as well as those from a number of previous reports, are discussed in relation to the possible aetiology of urolithiasis in the horse.

Renal calculi in dogs and cats: prevalence, mineral type, breed, age, and gender interrelationships (1981-1993).

Three hundred seventeen specimens of urinary calculi of renal origin from 214 female dogs and 103 male dogs, and 71 specimens of urinary calculi of renal origin from 38 female cats and 33 male cats were submitted for mineral analysis between July 1, 1981, and December 31, 1993. Among dogs, 45 breeds were affected with renal calculi. Thirty-three breeds and a crossbred group were represented among females, but 8 breeds and the crossbred group accounted for 81% of the total. Among male dogs, 30 breeds and a crossbred group were represented, but 7 breeds and the crossbred group accounted for 69% of the total. Among cats, 10 breeds and a crossbred group were represented. Dogs and cats with renal calculi were older than those of 2 comparison population groups. More than one-half of the renal calculi in both dogs and cats were from the 1st known episode of urolithiasis. The risk of formation of renal calculi was found to be higher for cats than for dogs, when compared to other stone-forming cats and dogs (approximately 4.95 per 100 stone-forming cats and 2.88 per 100 stone-forming dogs). Among dogs, breeds at highest risk of developing renal calculi were Miniature Schnauzers, Shih Tzus, Lhasa Aposos, Yorkshire Terriers, and female Pugs. Also at high risk were male Dalmatians and male Basset Hounds. Among small dogs, females generally were at higher risk of developing renal calculi than were males. Regardless of size, terrier breed males generally were at higher risk of developing renal calculi. Breeds of dogs at low risk for development of renal calculi included crossbreds. German Shepherd Dogs, Labrador Retrievers, Golden Retrievers, and female Dachshunds. When only 1 kidney was involved, the risk of left renal calculus was greatest for both dogs and cats, but bilateral renal involvement was relatively common in both species (19% and 9%, respectively). Among dogs, specimens composed of 1 mineral substance (e.g., struvite) occurred more often in males (58.3%) than in females (37.9%). Female dogs formed renal calculi containing struvite or oxalate more often than did males; males formed calculi containing urate more often than did females. Calculi containing oxalate, apatite, or some combination of these minerals predominated among cats; only 1 specimen from 38 female cats and only 4 specimens from 33 male cats contained neither oxalate nor apatite. Crossbred cats were significantly less likely to have renal calculi than were other breeds. A single renal calculus specimen was identified in several uncommon breeds including Tonkinese and Birman cats, and Affenpinscher, Clumber Spaniel, English Shepherd, and Field Spaniel dogs. No significant differences were observed between male and female dogs or between male and female cats with regard to mineral type of the specimen and the presence of urinary tract infection.

An investigation into the effects of storage on the diagnosis of crystalluria in cats.

Urinalysis was performed on 41 cats with no history of urinary tract disease. Samples were divided into aliquots, stored under differing condition and then examined for the presence of crystalluria. Crystalluria was detected in at least one stored sample in 92% of cats fed a mixed wet/dry food diet compared to 24% in the fresh sample. Crystalluria was not detected in any sample or aliquot from cats fed all wet food diets.

Medical dissolution of struvite nephrolithiasis using amino acid preparation in dogs.

A new chemolytic therapy with amino acid preparation was tried for use on struvite renal stones in two dogs, which were admitted to Azabu University Veterinary Teaching Hospital. No other special diet, for the purpose of dissolving the stones, was fed during the treatment. Dissolution of the stones began at week 1, and no stone was detected on radiography at week 4 in both cases. The amino acid preparation thereafter has been administered every 2-3 days to prevent formation of the stones. After 6 months from treatment, complete dissolution was confirmed, and no relapse has been observed. Therefore, it is concluded that chemolytic therapy with amino acid preparation might be useful for the treatment of nephrolithiasis with struvite renal stones in dogs.