Proximal ureteral ectopia causing hydronephrosis in a kitten

A 2-month-old, female cat was presented for abdomen dilation. The patient was undernourished, and severe left hydronephrosis was diagnosed after clinical, ultrasonographical and radiographical examination. Although pyelography was performed in order to visualise the ureteral course, surgery was necessary to reach a final aetiological diagnosis and treatment. At gross examination, the left ureter crossed the renal capsula at the level of the caudal renal pole, and the subcapsular ureteral segment was markedly dilated. Distal to the renal capsula, the left ureter was very thin when compared to the right. The parenchyma of the left kidney, as suggested by ultrasonographical evaluation, was extremely reduced in thickness. An ureteronephrectomy was performed. Histopathological evaluation revealed glomerular sclerosis and diffuse parenchymal fibrosis. Severe hydronephrosis derived from an altered renal pelvic anatomy and abnormal ureteral course determining functional stenosis. Diagnosis of congenital anomaly before development of complications such as hydronephrosis could have allowed a surgical renal capsulectomy and obstruction relief. To the author's knowledge, this is the first report of severe hydronephrosis associated to altered renal pelvic anatomy and proximal ureteral ectopia in cat.     

Bilateral fusion of a supernumerary kidney in a cat

A rare case of bilateral fusion of a supernumerary kidney was found during the necropsy of a female, 8-year-old, mixed breed cat that died as a result of azotemia and chronic enteritis. Apart from enteritis, necropsy revealed four kidneys, two in the sublumbar left region and two in the sublumbar right region, with cortical and medullary regions well individualized and independent; however, the pelvis was partially fused, giving rise to a single ureter. The kidneys were small, whitish and firm, with irregular surfaces. Microscopically, all kidneys displayed normal renal glomeruli and tubules among the immature renal glomeruli and tubules with characteristics of hypoplasia. Foci of glomerulosclerosis, nephrocalcinosis and interstitial fibrosis were also observed.     

Study of association between histologic features and echogenicity of architecturally normal cat kidneys

Thirty-eight grossly and histologically normal cat kidneys were examined ultrasonographically. The echogenicity of the renal cortex was subjectively evaluated by scoring it as largely or not largely different from the echogenicity of the renal medulla and as similar or not similar to the echogenicity of the renal sinus. The presence or absence of a medullary hyperechoic band was determined. The length, width, and height of each kidney was measured. Hematoxylin and eosin-stained sections of each kidney were examined microscopically. The amount of fat vacuoles in the tubular epithelium of the renal cortex was scored as plentiful or not plentiful. The presence or absence of a medullary band of mineral deposits within the lumina of renal tubules was determined. A plentiful amount of fat vacuoles in renal cortex was associated positively with a large difference in echogenicity between cortex and medulla (P less than 0.01) and with similar echogenicity of cortex and sinus (P less than 0.01). The presence of a medullary hyperechoic band was associated positively with a band of mineral deposits within medullary tubular lumen (P 0.01). Kidneys with a large difference in echogenicity between cortex and medulla and kidneys with a plentiful amount of fat vacuoles were not significantly different in size (P = 0.56). These groups were larger (P less than 0.01) in length, width, and height than were kidneys without a large difference in echogenicity between cortex and medulla and kidneys that did not have plentiful cortical fat vacuoles.     

Evaluation of the renal effects of experimental feeding of melamine and cyanuric acid to fish and pigs

OBJECTIVE: To determine whether renal crystals can be experimentally induced in animals fed melamine or the related triazine compound cyanuric acid, separately or in combination, and to compare experimentally induced crystals with those from a cat with triazine-related renal failure. ANIMALS: 75 fish (21 tilapia, 24 rainbow trout, 15 channel catfish, and 15 Atlantic salmon), 4 pigs, and 1 cat that was euthanatized because of renal failure. PROCEDURES: Fish and pigs were fed a target dosage of melamine (400 mg/kg), cyanuric acid (400 mg/kg), or melamine and cyanuric acid (400 mg of each compound/kg) daily for 3 days and were euthanatized 1, 3, 6, 10, or 14 days after administration ceased. Fresh, frozen, and formalin-fixed kidneys were examined for crystals. Edible tissues were collected for residue analysis. Crystals were examined for composition via Raman spectroscopy and hydrophilic-interaction liquid chromatography-tandem mass spectrometry. RESULTS: All animals fed the combination of melamine and cyanuric acid developed goldbrown renal crystals arranged in radial spheres (spherulites), similar to those detected in the cat. Spectral analyses of crystals from the cat, pigs, and fish were consistent with melamine-cyanurate complex crystals. Melamine and cyanuric acid residues were identified in edible tissues of fish. CONCLUSIONS AND CLINICAL RELEVANCE: Although melamine and cyanuric acid appeared to have low toxicity when administered separately, they induced extensive renal crystal formation when administered together. The subsequent renal failure may be similar to acute uric acid nephropathy in humans, in which crystal spherulites obstruct renal tubules.     

Assessment of melamine and cyanuric acid toxicity in cats.

The major pet food recall associated with acute renal failure in dogs and cats focused initially on melamine as the suspect toxicant. In the course of the investigation, cyanuric acid was identified in addition to melamine in the offending food. The purpose of this study was to characterize the toxicity potential of melamine, cyanuric acid, and a combination of melamine and cyanuric acid in cats. In this pilot study, melamine was added to the diet of 2 cats at 0.5% and 1%, respectively. Cyanuric acid was added to the diet of 1 cat at increasing doses of 0.2%, 0.5%, and 1% over the course of 10 days. Melamine and cyanuric acid were administered together at 0%, 0.2%, 0.5%, and 1% to 1 cat per dose group. No effect on renal function was observed in cats fed with melamine or cyanuric acid alone. Cats dosed with a combination were euthanized at 48 hours after dosing because of acute renal failure. Urine and touch impressions of kidneys from all cats dosed with the combination revealed the presence of fan-shaped, birefringent crystals. Histopathologic findings were limited to the kidneys and included crystals primarily within tubules of the distal nephron, severe renal interstitial edema, and hemorrhage at the corticomedullary junction. The kidneys contained estimated melamine concentrations of 496 to 734 mg/kg wet weight and estimated cyanuric acid concentrations of 487 to 690 mg/kg wet weight. The results demonstrate that the combination of melamine and cyanuric acid is responsible for acute renal failure in cats.     

Renal cystadenoma in a domestic shorthair

An 11-year-old domestic shorthair was examined after an enlarged left kidney was palpated by the referring veterinarian. No abnormalities were noted on complete blood count, serum biochemical profile and total thyroxine concentration, and the urine specific gravity was 1.039. An abdominal ultrasound identified the presence of a large cystic structure on the caudal pole of the left kidney. No abnormalities of the right kidney were seen. A left ureteronephrectomy was performed, and the cat recovered uneventfully from the procedure and was discharged from the hospital 5 days after surgery. The cat remains clinically normal 16 months postoperatively. Histopathology of the removed kidney demonstrated the presence of a renal cystadenoma. This report describes the successful surgical treatment of a renal cystadenoma. Renal cystadenoma should be considered as a differential diagnosis when renomegaly is noted. To the author's knowledge, a renal cystadenoma has not been previously reported in a cat.     

Polycystic kidney disease in a cat

Bilateral polycystic kidney disease was diagnosed in a 3-year-old female Persian cat. An elevation of blood urea nitrogen, serum creatinine levels, and serum phosphorus were the only abnormalities found with serial serum chemical and urine analyses. Intravenous urography showed radiolucent areas in both kidneys. An attempted renal biopsy produced only fluid but no kidney tissue. Necropsy and histological findings confirmed a diagnosis of polycystic kidney disease.     

A review of phosphorus homeostasis and the impact of different types and amounts of dietary phosphate on metabolism and renal health in cats

Elevated concentrations of serum phosphate are linked with progression and increased case fatality rate in animals and humans with chronic kidney disease. Elevated concentrations of serum phosphate can be a risk factor for development of renal and cardiovascular diseases or osteoporosis in previously healthy people. In rodents, an excess intake of dietary phosphorus combined with an inverse dietary calcium : phosphorus ratio (<1 : 1) contributes to renal calcification. Renal injury also has occured in cats fed experimental diets supplemented with highly soluble phosphate salts, especially in diets with inverse calcium : phosphorus ratios. However, not all phosphorus sources contribute similarly to this effect. This review, which focuses on cats, summarizes the published evidence regarding phosphorus metabolism and homeostasis, including the relative impact of different dietary phosphorus sources, and their impact on the kidneys. No data currently shows that commercial cat foods induce renal injury. However, some diets contain high amounts of phosphorus relative to recommendations and some have inverse Ca : P ratios and so could increase the risk for development of kidney disease. While limiting the use of highly soluble phosphates appears to be important, there are insufficient data to support a specific upper limit for phosphate intake. This review also proposes areas where additional research is needed in order to strengthen conclusions and recommendations regarding dietary phosphorus for cats.     

Glomerulocystic kidney disease in a kitten

A 4-month-old 1-kg female Siamese-Manx cross kitten was evaluated because of renomegaly and renal failure. Ultrasonography and cytologic examination of a renal aspirate failed to provide an antemortem diagnosis. Histologic lesions included diffuse cystic dilatation of all tubules and Bowman's spaces in the renal cortex and occasional small glomerular tufts; the lesions were similar to those of glomerulocystic kidney disease of humans. Glomerulocystic kidney disease is a rare cause of early-onset renal failure, but should be considered when renomegaly is detected, cysts are not detected in the kidney by ultrasonography, and cytologic examination of a renal aspirate is nondiagnostic.     

Histopathologic findings and classification of feline renal transplants

Seventy-seven feline transplant kidney specimens, obtained from 1 to 3,183 days (9 years) after transplantation, were reevaluated histologically and classified on the basis of the Banff '97 guidelines for human renal transplant kidneys. Overall, this classification system appeared useful in detecting rejection reactions and confirmed the finding in humans that biopsies can diagnose subclinical rejection and therefore are an important diagnostic tool for the follow up of renal transplants. However, on the basis of serum creatinine values, the severity of the acute or active and chronic lesions was not accurately reflected by this scoring system. This is thought to be due to the significant differences in histologic rejection patterns, especially in acute or active rejection, in cats when compared with humans. Tubulitis, lymphocytic glomerulitis, and vasculitis, which are the main pillars of the Banff '97 acute or active rejection scoring system, are either rare or not found in cats. The presence of significant necrotizing glomerulitis and vasculitis in feline renal transplants might imply that the rejection is complicated by acute antibody-mediated rejection. Alternatively, cyclosporine toxicity also should be considered because some of these kidneys show other signs of cyclosporine toxicity. Finally, the significance of subcapsular and interlobular phlebitis, rarely described in human rejection reactions but a distinct entity in cats, is unknown. From this study, it is clear that there are significant differences in the histology of acute or active rejection between humans and cats and that a better understanding of the histologic appearance of renal allografts will be especially beneficial for treatment and prognostic purposes.     

Preliminary study of urinary excretion of liver-type fatty acid-binding protein in a cat model of chronic kidney disease

Urinary liver-type fatty acid-binding protein (uL-FABP) is a clinically useful biomarker for monitoring chronic kidney disease (CKD) in humans. However, long-term monitoring of uL-FABP in CKD cats has not been reported. The objective of this preliminary study was to investigate whether the urinary excretion of L-FABP could predict the deterioration of renal function in 2 CKD model cats. Urinary liver-type fatty acid-binding protein (uL-FABP) increased before standard renal biomarkers, including serum creatinine, blood urea nitrogen, and symmetric dimethylarginine, in 1 cat with deteriorating renal function, but remained low and relatively stable in another cat with stable renal function. Our results suggest that uL-FABP is a potential clinical biomarker for predicting the progression of CKD in cats, as it is in humans.     

Gene delivery to renal tubular epithelial cells using adeno-associated virus vector in domestic cats

Recombinant adeno-associated virus (rAAV) vectors provide excellent gene delivery into the kidney in several mammals. This study evaluated gene delivery into the cat kidney using an rAAV vector. First, infection and reporter gene expression using rAAV vector encoding the enhanced green fluorescent protein gene (rAAV-EGFP) was examined in vitro in epithelial crandell reese feline kidney (CRFK) cells. At 12 h after transduction, green fluorescence was detected in cells. Next, the rAAV-EGFP construct was injected into the kidneys of two anesthetized cats via the skin, similar to a renal biopsy. On 3 and 12 days after injection, green fluorescence was detected in renal tubules localized near the injected site, but not in glomeruli, blood vessels, or interstitial cells. Finally, the rAAV-EGFP construct was transduced into kidney sections cultured ex vivo. EGFP was expressed in renal tubules between the outer cortex and inner medulla regions. These results demonstrate that rAAV vectors effectively mediate gene delivery into cat renal tubules, and may prove usefulness in gene therapy for cats with renal diseases.     

Water transport in the kidney and nephrogenic diabetes insipidus

Nephrogenic diabetes insipidus is caused by an inability of the kidney to concentrate urine despite adequate concentration of vasopressin in blood and is characterized by polyuria, polydipsia, and hyposthenuria in the presence of plasma hyperosmolality. Nephrogenic diabetes insipidus is the result of defects in water homeostasis in the kidney. Nephrogenic diabetes insipidus occurs when the kidneys cannot or do not respond to vasopressin. There are 2 categories of nephrogenic diabetes insipidus. Congenital nephrogenic diabetes insipidus is a rare, inherited, irreversible cause of polyuria and polydipsia in humans that is even rarer in animals. Acquired nephrogenic diabetes insipidus is more common and is often secondary to illness or medication that interferes with the action of vasopressin in the renal tubules. Unlike congenital nephrogenic diabetes insipidus, acquired or secondary nephrogenic diabetes insipidus is often reversible with correction of the associated or causative problem.     

Leptospira in slaughtered fattening pigs in southern Vietnam: presence of the bacteria in the kidneys and association with morphological findings

One kidney was collected from each of 32 fattening pigs at an abattoir in southern Vietnam in 2001 in order to demonstrate infecting Leptospira serovar and to associate renal macro- and microscopic findings with the presence of renal leptospires. Leptospires were demonstrated in 22 (69%) of the investigated kidneys by immunofluorescence. Multifocal interstitial nephritis (MFIN) and gross renal lesions (white spots) were each demonstrated in 24 (75%) kidneys. Leptospira interrogans serovar bratislava was isolated from one kidney. There was no association between presence of leptospires and MFIN (P=0.19), respectively and white spots (P=0.98), respectively. These data suggest that Leptospira infection is common among fattening pigs in the study area and that these animals may be considered as an occupational human health hazard. It is also suggested that the presence of white spots is an unreliable indicator of the presence of renal leptospires.     

Polycystic kidney disease in a Persian cat

This case report is about a 9-year-old male castrated Persian cat with chronic renal failure. After physical examination and ultrasonography polycystic kidney disease (PKD) was diagnosed. Various aspects of etiology, pathophysiology and diagnosis of PKD are discussed.     

Feline polycystic kidney disease in Persian and other cats: a prospective study using ultrasonography

OBJECTIVE: To determine the prevalence of feline polycstic kidney disease in Persian cats presented to the University of Melbourne Veterinary Clinic and Hospital between February and August 1999. DESIGN: A prospective clinical study using client owned animals was performed. PROCEDURE: Two hundred and fifty Persian cats, ranging in age from 13 weeks to 10 years, were presented to the University of Melbourne Veterinary Clinic and Hospital for ultrasound examination of both kidneys. The cats were placed in dorsal and lateral recumbency and alcohol and ultrasonic coupling gel were applied to the skin. The kidneys were examined ultrasonographically in longitudinal, sagittal and transverse planes. Results were recorded for each cat at the time of examination as either negative or positive for PKD. In addition 14 Exotics (short-haired Persians), 4 Ragdolls and 3 British Short-Hair cats were examined. RESULTS: Forty five percent of Persian cats examined were found to be positive for feline polycystic kidney disease on the basis of presence of anechoic cysts within the renal parenchyma. These cats ranged in age from 13 weeks to 10 years. Fifty per cent of the Exotic cats were positive for polycystic kidney disease whereas all Ragdolls and British Short Hairs were negative for the disease. Only one positive cat was reported to be showing clinical signs of renal disease. CONCLUSION: The prevalence of feline polycstic disease in Persian cats presented to the University of Melbourne between February and August 1999 was 45%. Exotic cats were found to have the slightly higher incidence of 50%.     

Renal fibrosis in feline chronic kidney disease: Known mediators and mechanisms of injury

Chronic kidney disease (CKD) is a common medical condition of ageing cats. In most cases the underlying aetiology is unknown, but the most frequently reported pathological diagnosis is renal tubulointerstitial fibrosis. Renal fibrosis, characterised by extensive accumulation of extra-cellular matrix within the interstitium, is thought to be the final common pathway for all kidney diseases and is the pathological lesion best correlated with function in both humans and cats. As a convergent pathway, renal fibrosis provides an ideal target for the treatment of CKD and knowledge of the underlying fibrotic process is essential for the future development of novel therapies. There are many mediators and mechanisms of renal fibrosis reported in the literature, of which only a few have been investigated in the cat. This article reviews the process of renal fibrosis and discusses the most commonly cited mediators and mechanisms of progressive renal injury, with particular focus on the potential significance to feline CKD.     

Resolution of renal adenocarcinoma-induced secondary inappropriate polycythaemia after nephrectomy in two cats

Two cases of secondary, inappropriate polycythaemia caused by renal adenocarcinoma in domestic shorthair cats, are described. The cats were 9 and 12 years old and both were presented because of generalised seizures presumably due to hyperviscosity. Both cats had a markedly increased haematocrit (0.770 and 0.632 l/l) and thrombocytosis (744 x 10(9)/l and 926 x 10(9)/l). An abdominal ultrasound revealed a mass in the cranial pole of one kidney in both cats. Serum erythropoietin (EPO) concentration was within the reference interval (RI) in both cats but was inappropriately high considering the markedly increased haematocrit. The cats were initially stabilised and managed by multiple phlebotomies and intravenous fluid therapy and underwent nephrectomy of the affected kidney later on. Both the polycythaemia and thrombocytosis resolved following surgery. Postoperative serum EPO concentration, measured in one cat, decreased markedly. Histopathology of the affected kidneys confirmed a diagnosis of renal adenocarcinoma. Both cats were stable for an 8-month follow-up period; however, one cat had developed a stable chronic kidney disease (CKD), while the other was represented 8 months postoperatively due to dyspnoea, and had radiographic evidence of lung metastasis, presumably because of the spread of the original renal tumour and was euthanased. Initial stabilisation of polycythaemic cats should include multiple phlebotomies. Nephrectomy should be considered in cats with secondary, inappropriate, renal adenocarcinoma-related polycythaemia when only one kidney is affected by the tumour, and provided that the other kidney's function is satisfactory. Nephrectomy should be expected to resolve the polycythaemia and lead to normalisation of serum EPO concentration.     

Hypothermic Storage of Feline Kidneys for Transplantation: Successful Ex Vivo Storage Up to 7 Hours

Objective—To describe the effect of hypothermic storage on transplanted feline kidneys.
Study Design—Kidneys were stored in University of Wisconsin (UW) sodium gluconate (n = 3) or phosphate-buffered sucrose (n = 5) solutions before transplantation.
Animal Population—Eight cats with renal failure and seven normal cats as kidney donors.
Methods—Kidneys were perfused through the renal artery with cold (10°C) storage solution and immersed in the solution on ice until transplantation.
Results—Mean ex vivo storage time was 4.8 ± 0.36 hours (range, 3.5 to 7 hours). Seven recipient cats survived surgery. Five of the cats had decreased serum creatinine concentrations from a mean of 8.2 mg/dL (range, 4.0 to 15.8 mg/dL) preoperatively to 1.7 mg/dL (range, 1.3 to 2.2 mg/dL) within 4 days of surgery. In one cat, serum creatinine concentration dropped from 15.1 to 3.7 mg/dL in 3 days, but the cat developed a ureteral stricture that required revision. One graft did not function, and the cat died on day 19. The mean postoperative survival time of cats that were discharged from the hospital (n = 6) was 254 days (range, 49 to 717 days) at the time of this report. Long-term renal function (>60 days postoperatively; n = 5) was excellent with mean serum creatinine concentrations of 1.6 ± 0.15 mg/dL.
Conclusions—Hypothermic storage is feasible for short-term preservation of feline kidneys.
The maximal length of feasible storage remains unknown.
Clinical Relevance—Hypothermia protects against ischemia-induced nephron loss during ex vivo manipulation of the allograft and allows longer safe vascular anastomosis times. Short-term hypothermic storage also provides time to accommodate modifications in scheduling or anesthetic management of the recipient operation.     

Systemic Exophiala jeanselmei infection in a cat

A 14-year-old spayed domestic shorthair cat was referred for ultrasonographic evaluation of abnormally shaped kidneys. Multifocal lesions were detected ultrasonographically in the liver and kidneys; a fine-needle aspirate of the kidneys was performed, and numerous clumps of fungal hyphae were identified. The following day, the cat was recumbent with advanced neurologic signs. The cat was euthanatized, and a necropsy was performed. Multifocal granuloma-like masses were seen on the liver, kidneys, abdominal wall, mesentery, thoracic wall, pericardium, and epicardium. Similar lesions were found on the cervical portion of the spinal cord, the cerebrum, and cerebellum. Exophiala jeanselmei, an organism of the phaeohyphomycotic group, was identified on fungal culture. To our knowledge, systemic infections caused by this organism have not been reported. However, phaeohyphomycotic infections are believed to be an emerging disease in humans.