Early Detection of Renal Damage and Disease in Dogs and Cats

Rapid identification of canine uropathogens by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and the clinical factors that correlated bacterial species and antimicrobial resistance

Using the matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) method for bacterial diagnosis, rapid urine sample preparation can reduce time relapsing of diagnosis and improve discriminatory power in coinfection cases. We aimed to evaluate rapid urine preparation procedures before MALDI-TOF MS application using dog clinical urine samples in comparison with standard microbiological diagnostic methods by agreement analysis. We determined the frequency and distribution of bacteria and bacterial resistance and their correlations to clinical history. Three experimental procedures comprising direct centrifugation, 10% sodium dodecyl sulfate digestion, and ultrasonic preparation were performed for method validation and sensitivity. Sterile urine containing Escherichia coli and/or Staphylococcus aureus were used as simulated samples. By ultrasonic preparation, the microorganisms could be detected 1.46-1.51 × 105 CFU, which was considered the most suitable technique. This preparation was significantly consistent with the routine method based on data from Hospital Information Systems for 50 urine samples from canine cystitis. By standard protocol, Enterobacteriaceae and Staphylococcus pseudintermedius were found in most of the 155 urine samples with cystitis. Extended-spectrum beta-lactamase-producing Enterobacteriaceae was found in 25-30% of the samples. Imipenem resistance was found in 70% of Acinetobacter baumannii cases; almost all were resistant to second-generation fluoroquinolones and tetracyclines. The most efficient antibiotic for treating bacterial urinary tract infection was amoxicillin plus clavulanic acid. A. baumannii and Pseudomonas aeruginosa were susceptible to pradofloxacin. Prolonged urine catheterization was linked to lower urinary tract infections by Enterobacter spp., which also correlated with chronic kidney disease.

[Role of systemic infections in canine kidney diseases]

Kidney diseases represent a common problem as well as a frequent cause of death in dogs. Infectious agents may be responsible for glomerulopathies and acute kidney injuries. Many infections commonly associated with the development of immune complex glomerulonephritis in central and southern Europe are important as travel-associated diseases in Germany. These include leishmaniosis, dirofilariosis, and ehrlichiosis. Rarely, anaplasmosis, hepatozoonosis, Lyme disease as well as babesiosis caused by small Babesia spp. are detected as cause of canine immune complex glomerulonephritis in Germany. Leptospirosis, canine infectious hepatitis, and babesiosis caused by large Babesia spp. may be responsible for the development of acute kidney injuries associated with tubulointerstitial nephritis. Therefore, further diagnostics aiming at identifying potentially causative infectious agents in dogs with renal disease is important for both prognosis and therapy of the patient.

The Source Matters-Effects of High Phosphate Intake from Eight Different Sources in Dogs

Elevated serum phosphate concentrations are an established risk factor for cardiovascular disease and mortality in chronic kidney disease in various species. Independent associations of other parameters of phosphorus metabolism, such as phosphorus intake from different sources and serum concentrations of phosphorus, as well as parameters involved in the regulation, such as parathyroid hormone (PTH) or markers of bone turnover, have been studied in less detail. Therefore, the serum kinetics of phosphate, PTH, and the bone resorption marker bone-specific alkaline phosphatase (BAP) were investigated after 18 days of feeding a control diet and diets supplemented with eight different organic and inorganic phosphate sources aiming at 1.8% phosphorus per dry matter and calcium to phosphorus ratio between 1.3 and 1.7 to 1. Eight healthy beagle dogs (f/m, 2-4 years, 12.9 ± 1.4 kg body weight) were available for the trial. Highly significant differences in the serum kinetics of phosphorus, PTH, and BAP with the highest postprandial levels after feeding highly water-soluble sodium and potassium phosphates were found. We conclude that the use of certain inorganic phosphates in pet food is potentially harmful and should be restricted.

Cystatin C and Iris: Advances in the Evaluation of Kidney Function in Critically Ill Dog

Critically ill hospitalized dogs are subject to certain complications, being acute kidney injury (AKI) a common one. Early diagnosis is crucial, and Cystatin C (CysC) is a reliable and early biomarker. The International Society of Renal Interest (IRIS) states that AKI severity can be assessed by mild changes in creatinine serum levels or reduction of urine output that cannot be considered biomarkers of renal injury but failure or insufficiency. Twenty-eight dogs admitted to the Intensive Care Unit under risk factors for the development of AKI were evaluated. Blood samples were collected for determination of sCr and CysC at admission and after 24, 48, and 72 h. Urine output was measured by daily monitoring, measured by collection in a closed system. The results showed the incidence of AKI was 67.9% based on the IRIS criteria and 78.6% based on cystatin C in critically ill patients' dogs. The measurement of serum cystatin C immediately on admission to the ICU was superior in the early identification of patients with AKI when compared to the IRIS classification and serum creatinine in critically ill dogs.

Alterations of Serum Biochemical and Urinary Parameters in a Canine Population before and after Intravenous Contrast Administration

Intravenous iodinated contrast (IVIC) medium is routinely administered to dogs. Scattered information exists regarding the serum biochemical or urinary profiles associated with the administration of IVIC in dogs. The aim of the study was to describe, compare, and discuss from the perspective of previous studies the alterations in serum biochemical and urinary parameters before (T0) and within one week (T1) of the IVIC administration during routine computed tomography (CT) scan evaluation of 22 dogs. Mature dogs presenting for CT scan evaluation for preoperative oncology staging/surgical planning were included. T1 evaluation was performed within one week of IVIC administration. Statistically significant differences in serum total protein, albumin, chloride, calcium, and phosphorus concentrations, urine protein to creatinine ratio, and urine specific gravity were found between T1 and T0. At T1, the serum creatinine concentration was within reference ranges in all dogs but one. An increase in the urine protein to creatinine ratio was observed in four samples, one of which was non-proteinuric at T0. Changes in biochemistry and urine parameters between T0 and T1 were not considered clinically significant.

Evaluation of Chronic Kidney Disease Progression in Dogs With Therapeutic Management of Risk Factors

This research was performed to describe the characteristics of the progression of naturally occurring chronic kidney disease (CKD) in dogs, together with the management of identified risk factors, following the International Renal Interest Society recommendations. Dogs diagnosed and staged with CKD, and with a longitudinal follow-up from the moment of diagnosis of up to a maximum of 730 days, were included. A total of 545 dogs that presented risk factors for the development of CKD were analyzed, out of which 36 met the inclusion criteria. Advanced age was identified in 80.6% of cases. Initiation risk factors were represented by inflammatory/infectious diseases, history of anesthetic-surgical procedures, heart disease, neoplasms, endocrinopathies, and exposure to nephrotoxic drugs. During the follow-up period, progression of CKD was identified in 47.2% of the cases, being more salient in advanced stages. Serum symmetric dimethyl arginine (SDMA) was the only glomerular filtration rate (GFR) marker which displayed differences among studied times during early stages of CKD, associated with the disease progression and decline of renal function. A significant difference between the survival curves in early and advanced CKD stages was observed. The factors related to decreased survival were hyperphosphatemia, anemia, and low body condition score (BCS). No differences were found between the presence of arterial hypertension and renal proteinuria and decreased survival. Furthermore, CKD diagnosis based on the persistent finding of abnormalities in early disease markers, such as serum symmetric dimethyl arginine increase and/or renal proteinuria, and timely therapeutic management of risk factors, allowed for CKD stabilization, reducing progression to advanced stages, and favoring higher survival rates.

The new age of renal biomarkers: does SDMA solve all of our problems?

Within clinical small animal practice, diagnosis of both chronic kidney disease and acute kidney injury is common. To assess renal function, measurement of glomerular filtration rate is considered the gold standard. Currently, routine tests of kidney function include surrogate markers of glomerular filtration rate such as serum creatinine, and urea, each with their own limitations, whilst urine protein to creatinine ratio gives an indication of glomerular and tubular handling of protein, and urine specific gravity information about urine concentrating ability by the kidney. These parameters are used together with historical and physical examination data to give a diagnosis of kidney disease following which creatinine, proteinuria and blood pressure are used to stage chronic kidney disease and, together with urine output, grade acute kidney injury according to the International Renal Interest Society. However, there has been much concern that creatinine is insensitive when used to indicate early decline in renal function and this has highlighted the need for additional methods of diagnosing and monitoring these patients, with the potential to allow earlier therapeutic intervention. Symmetric dimethylarginine is a novel biomarker, which has been shown to perform as a surrogate marker of glomerular filtration rate in small animals. This article will review current research on symmetric dimethylarginine and the ways in which it may be utilised in small animal practice; current research supports the use of symmetric dimethylarginine as a screening test for detection of early chronic kidney disease according to International Renal Interest Society guidelines, but further research is required in to the usefulness of symmetric dimethylarginine as a tool for monitoring disease and the effect of non-renal influences.

Renal ultrasonographic shear-wave elastography and urinary procollagen type III amino-terminal propeptide in chronic kidney disease dogs

Background and Aim:

Renal fibrosis is a well-established pathological alteration associated with chronic kidney disease (CKD) in several species and progresses as CKD advances. Although a renal biopsy is the gold standard for determining renal fibrosis, it is an invasive, impractical method for clinical practice. In humans, ultrasonographic shear-wave elastography (SWE), a novel advanced diagnostic imaging tool, can evaluate renal parenchyma stiffness, and urinary procollagen type III amino-terminal propeptide (uPIIINP), a promising renal fibrosis biomarker in humans, has increasingly been use applied to reduce the biopsies. This study compares renal tissue elasticity observed through SWE Young’s modulus (E) values between healthy dogs (HD) and those with CKD.

Materials and Methods:

The E value acquired by SWE, uPIIINP levels, and renal function were evaluated in 15 CKD dogs and 15 HD.

Results:

The renal cortical E values were significantly higher than the renal medullary E values in both groups (p<0.001). Renal cortical and medullary E values in CKD dogs were significantly higher than in HD (p<0.01). Cortical E values had greater significant correlations with renal functional parameters than the medullary E values and had a significant positive correlation with concentrations of plasma creatinine (Cr) (p<0.001); blood urea nitrogen (p<0.01); urine protein Cr ratio (p<0.01); and fractional excretions of sodium (p<0.05), potassium (p<0.05), chloride (p<0.05), and magnesium (p<0.001) while they had a negative correlation with urine specific gravity (p<0.05) and urine osmolality to plasma osmolality ratio (p<0.05). The uPIIINP to Cr (uPIIINP/Cr) ratios of CKD dogs were higher than those of HD (p<0.001). Moreover, the uPIIINP/Cr levels presented significant correlations with the renal cortical E values (p<0.01) and also the renal functional parameters.

Conclusion:

SWE offers a complementary, non-invasive diagnostic imaging tool for evaluating renal tissue stiffness in CKD dogs with renal function deterioration. In addition, uPIIINP levels are associated with renal function and structural changes in dogs. Therefore, the uPIIINP level might be a non-invasive, complementary, and promising biomarker for evaluating renal fibrosis in canine CKD.

Electrophoretic analysis (sds-page) of canine urinary proteins according to the stage of chronic kidney disease

ABSTRACT Glomerular proteinuria is characterized by the loss of high-molecular-weight proteins (HMWPs), while tubulointerstitial proteinuria is characterized by the loss of low-molecular-weight proteins (LMWPs). The objective was to assess the molecular weight of urinary proteins (MWUP) in dogs with naturally acquired CKD and determine the proportion of HMWPs and LMWPs according to CKD stage. Twenty-eight dogs with CKD were recruited and divided into 4 groups based on serum creatinine (Cr) levels (group1: Cr<1,4, n=8; group2: 1,4<Cr<2,0, n=6; group3: 2,1<Cr<5, n=9; group4: Cr>5,0, n=5). The control group consisted of 5 healthy dogs. The MWUP was determined by SDS-PAGE. The urinary protein-to-creatinine ratio (UP/C) was used to quantitatively assess proteinuria. The electrophoresis pattern revealed a proportionally greater loss of HMWPthan of LMWP in all groups with CKD and an increased loss of LMWP in group 4 (P<0.05). These results suggest a predominance of glomerular injuries throughout all stages of CKD in these dogs and an increase in tubulointerstitial injury towards the end-stage of the disease. The results of the present study support the recommendation of SDS-PAGE as an effective technique for the qualitative assessment of proteinuria, as well as a method for assessing the severity and location of renal injury.

Association between breed and renal biomarkers of glomerular filtration rate in dogs

Background

Kidney disease, especially chronic kidney disease (CKD), is common in older dogs. The biomarkers symmetric dimethylarginine (SDMA) and creatinine (Cr) are indicators of glomerular filtration rate (GFR). This retrospective study used these biomarkers to identify groups at risk of decreased GFR at the breed level.

Methods

Data from dogs with a single serum chemistry result that included Cr and SDMA submitted between July 2015 through December 2017 were included. Dogs were identified by breed and age group. Decreased GFR was defined as Cr above 1.9 mg/dl or SDMA above 18 µg/dl.

Results

Fourteen breeds had a significantly higher percentage of dogs with increased SDMA or Cr for one or more age groups. Geriatric and senior Shetland sheepdogs, Yorkshire terriers and Pomeranians were significantly more likely to have increased renal biomarkers. Boxers were identified with significantly increased renal biomarkers in the age groups spanning two months to 10 years of age.

Conclusion

Evidence of decreased GFR occurred commonly in older dogs of most breeds, especially geriatric dogs greater than 10 years of age, but there were some exceptions, with more significant changes affecting younger animals of several breeds. The combination of SDMA and Cr identified more cases of decreased GFR than either SDMA or Cr alone.

Clinical-diagnostic criteria and peculiarities of treatment of urocystitis in cats

The results of a study of cats with signs of urocystitis are presented. The general principles of diagnostics based on clinical, laboratory and additional research methods are established. Clinically acute urocystitis was manifested by disorders of urination – pollakiuria, dysuria, stranguria. Some of the animals showed an increase in body temperature, pain in the bladder and tightness of the walls of the abdominal cavity. According to the results of urine study, it was observed that 43.7% of the cats with urocystitis showed an increase in relative density of the urine, a change in urine pH towards higher alkaline levels, urine residue – erythrocytes, leukocytes and microorganisms were indicated. Impurities of salt and sand were found in 58.4% of the cats. In 31.4% of the cats, urocystitis was a complication of urolithiasis. Early diagnosis, especially differential diagnosis of acute and chronic, secondary urocystitis presents difficulties. Therefore, in cases of suspected inflammatory diseases of the urinary tract, a complex examination using ultrasound of the kidneys, bladder, prostate gland (in males) and the uterus (in females) is recommended.With therapeutic purpose, sick cats (two groups of 8 animals/group) were administered: anti-microbial agent (5% solution of Enrofloxacin), spasmolytic medicinal agent – Riabal®. Animals of the second group were additionally administered the drug Cystocure (Candioli Farmaceutici). According to the instructions, the plant basis of the powder Cystocure is presented by extracts of cranberries and orange peels. These substances provide the main properties of the drug – help in resisting the bacterial colonization of the lower urinary tract and change in urine pH to the acid side. The applied therapy positively influenced the clinical condition of the cats. Their general health was improved, painful sensations during the act of urination disappeared, the quantity and frequency of diuresis normalized. On the seventh day of treatment, according to the results of the study, the urine became transparent, no microorganisms were detected. In cats of the second group, which additionally used the drug Cystocure, the amount of salts and sand decreased significantly, the pH of the urine did not exceed the recommended value of 6.4, in contrast to animals of the first group.

Urinary heat shock protein-72: A novel marker of acute kidney injury and chronic kidney disease in cats

Acute kidney injury (AKI) in cats is associated with high mortality, partially attributed to late recognition of the disease when using currently available markers. Feline chronic kidney disease (CKD) has a variable progression rate. This study aimed to evaluate the sensitivity and specificity of urinary heat shock protein-72 to urinary creatinine ratio (uHSP72:uCr) as a diagnostic and prognostic marker in feline AKI, and as a prognostic indicator in feline CKD. The study included 63 cats, divided into five groups: healthy controls (n=10), urethral obstruction (UO; n=7), CKD (n=15), AKI (16 cats) and acute decompensating CKD (ACKD; n=15). Median uHSP72:uCr (ng/mg) of healthy, UO, CKD, AKI and ACKD cats were 0.44 (range, 0.13-1.1), 1.96 (range, 0.64-11.9), 4.2ng/mg (range, 0.57-22.16), 3.2 (range, 0.42-10.91) and 7.0 (range, 1.2-20.96), respectively, and differed (P<0.001) among groups. uHSP72:uCr was significantly lower in the controls vs. the CKD, AKI and ACKD groups. Receiver operator characteristic analysis of uHSP72:uCr, including the AKI and control groups, showed an area under the curve of 0.93 (95% confidence interval, 0.84-1.00), indicating an excellent predictive performance for diagnosing AKI. A 0.54ng/mg cutoff point corresponded to 94% sensitivity and 70% specificity for diagnosing AKI. The median survival time of cats with CKD with low uHSP72:uCr was longer (P=0.036) than in those with high uHSP72:uCr (561 vs. 112 days, respectively). uHSP72:uCr is a highly sensitive, moderately specific marker of AKI in cats, and is associated with the survival of cats with CKD.

Renal perfusion parameters measured by contrast-enhanced ultrasound in healthy dogs demonstrate a wide range of variability in the long-term

Contrast-enhanced ultrasound may be helpful for detecting early renal microvascular damage and dysfunction in dogs. However, before this noninvasive imaging method can be tested as an early-stage screening tool in clinical patients, an improved understanding of long-term variation in healthy animals is needed. In this prospective, secondary, longitudinal, serial measurements study, variability of contrast-enhanced ultrasound renal perfusion parameters was described for eight healthy dogs, using seven time points and a period of 83 weeks. Dogs were sedated with butorphanol (0.4 mg/kg), and contrast-enhanced ultrasound of each kidney was performed after an intravenous bolus injection of a microbubble contrast agent (0.04 mL/kg). Time-intensity curves were created from regions-of-interest drawn in the renal cortex and medulla. Intensity-related parameters representing blood volume and time-related parameters representing blood velocity were determined. A random-effects model using restricted maximum likelihood was used to estimate variance components. Within-dog coefficient of variation was defined as the ratio of the standard deviation over the mean. Time-related parameters such as time-to-peak, rise and fall time had lowest within-dog variability. Intensity-related parameters such as peak enhancement, wash-in and wash-out area under the curve, total area under the curve, and wash-in and washout rates had high within-dog variability (coefficient of variation > 45%). Authors therefore recommend the use of time-related parameters for future studies of renal perfusion. Within-dog variability for bilateral kidney measurements was extremely low, therefore contrast-enhanced ultrasound may be particularly useful for detecting unilateral changes in renal perfusion. Future studies are needed to compare contrast-enhanced ultrasound findings in healthy dogs versus dogs with renal disease.

Variability of serum concentrations of cystatin C and urinary retinol-binding protein, neutrophil gelatinase-associated lipocalin, immunoglobulin G, and C-reactive protein in dogs

Background

Markers of kidney dysfunction and damage have potential to detect chronic kidney disease (CKD) in early stages. However, data on long‐term variation of these markers in healthy dogs is lacking and is crucial for the interpretation of results.

Hypothesis/Objectives

To determine temporal variations of serum cystatin C (sCysC) and urinary retinol‐binding protein (uRBP), neutrophil gelatinase‐associated lipocalin (uNGAL), immunoglobulin G (uIgG), and C‐reactive protein (uCRP) in healthy dogs.

Animals

Eight clinically healthy adult Beagles were evaluated.

Methods

Longitudinal observational study. Serum cystatin C was determined by particle‐enhanced nephelometric immunoassay. Urinary retinol‐binding protein, uNGAL, uIgG and uCRP were determined by ELISA and concentrations were indexed to urinary creatinine. Within‐ and between‐dog variance components (VC) and within‐dog coefficients of variation (CV) were determined from blood and urine collected at eight time points over 1.5 years.

Results

Urinary C‐reactive protein (uCRP) concentrations were consistently below the detection limit (5.28 ng/mL). Mean ± within‐dog standard deviation for sCysC, uRBP/c, uNGAL/c and uIgG/c was 0.15 ± 0.01 mg/L, 0.09 ± 0.03 mg/g, 2.32 ± 2.03 μg/g and 12.47 ± 10.98 mg/g, respectively. Within‐dog CV for sCysC, uRBP/c, uNGAL/c and uIgG/c was 8.1%, 33.7%, 87.2% and 88.1%, respectively.

Conclusions and clinical importance

Serum cystatin C, uRBP/c, uNGAL/c and uIgG/c exhibit a wide range of long‐term within‐dog variability. Researchers and veterinarians might need to take this into account when interpreting their results. To assess their diagnostic and predictive ability, future studies need to establish reference ranges for healthy dogs and dogs with CKD.

Renal phosphorus excretion in adult healthy cats after the intake of high phosphorus diets with either calcium monophosphate or sodium monophosphate

Renal and faecal phosphorus excretion of adult healthy European shorthaired cats after the intake of high phosphorus diets (meat/rice based) with either calcium monophosphate (HP-CaP) or sodium monophosphate (HP-NaP) as main phosphorus source was compared. The control diets (CON-CaP and CON-NaP, respectively) did not contain any added phosphorus. Calcium/phosphorus ratio was adjusted to 1.3/1 by adding calcium carbonate. Twenty-three cats were available for the trials. All cats were fed the control diets for 29 days; then, the HP diets were tested for 29 days against controls in a crossover design. Faeces and urine were collected in the last 10 days of each trial. Phosphorus in food, faeces and urine was measured by photometry after wet digestion. Phosphorus intake amounted to 84 ± 10 mg/kg body weight (BW) in CON-NaP (n = 13) and to 74 ± 7 in CON-CaP (n = 12). In the HP groups, the intake was 255 ± 34 mg/kg BW (HP-NaP; n = 13) and 216 ± 20 mg/kg BW (HP-CaP; n = 12). The sodium monophosphate in group HP-NaP led to a higher renal phosphorus excretion (83 ± 15 mg/kg BW) than the calcium monophosphate (25 ± 5 mg/kg BW; p < 0.05), even though the apparent phosphorus digestibility was higher in HP-CaP than in HP-NaP (p < 0.05). Faecal calcium excretion was strictly correlated to faecal phosphorus excretion (r²  = 0.98). The same was true for calcium and phosphorus balance (r²  = 0.89). In group HP-NaP, seven of 13 cats showed glucosuria. By contrast, in HP-CaP glucosuria was not observed. Highly water-soluble inorganic phosphorus sources such as sodium phosphate are likely to lead to phosphaturia and may present a risk for renal health of cats.

A nutraceutical diet based on Lespedeza spp., Vaccinium macrocarpon and Taraxacum officinale improves spontaneous feline chronic kidney disease

Chronic kidney disease is characterized by structural and/or functional impairment of one or both kidneys persisting for more than 3 months. In cats, chronic kidney disease can frequently occur in animals aged over 9 years with an incidence of approximately 10%. Thirty-four client-owned, neutered cats, suffering from stage II-III chronic kidney disease and diagnosed according to the International Renal Interest Society guidelines were randomly assigned to receive either a control diet (n = 17) or a nutraceutical diet (ND; n = 17) for 90 days. Both diets were commercialized for management of CKD symptoms. The diets were identical except that the ND contained tablets that consisted of 60-80% hydrolysed proteins, 20-40% minerals and active substances, that are, Lespedeza spp. 0.0588%, Vaccinium macrocarpom 0.0371%, and Taraxacum officinale 0.0231%. No adverse effects were reported during this study. Both diets resulted in an improvement in CKD symptoms. After a 90-day evaluation, creatinine, blood urea nitrogen, total proteins, and aspartate aminotransferase significantly decreased in cats that received the ND. A significant decrease was also observed in urine turbidity score, color score, and total proteins in cats that received the ND. We have found that a ND based on Lespedeza spp., Vaccinium macrocarpon, and Taraxacum officinale improves key indicators of renal failure in cats affected by chronic kidney disease.

Effect of a high phosphorus diet on indicators of renal health in cats

Objectives High phosphorus intake may further impair renal health in cats with chronic kidney disease (CKD). The hypothesis that a high phosphorus (HP) diet might be nephrotoxic for healthy animals was tested in cats, a species with a high incidence of naturally occurring CKD. Methods Thirteen healthy adult cats were fed a phosphorus excess diet (about five times maintenance requirements), and this HP group was compared with cats on a balanced control diet (CON). The trial lasted for 29 days (10 days of faeces and urine collection). Endogenous creatinine clearance was determined towards the end of the trial. Fresh urine was tested for glucose and proteins. Results Glucosuria and microalbuminuria were observed exclusively in the HP group in 9/13 cats. Creatinine clearance was significantly decreased after feeding HP. In the HP group phosphorus was highly available (apparent digestibility around 60%). Renal phosphorus excretion was significantly increased in the HP group (115 mg/kg body weight/d vs 16 mg/kg body weight/d in the CON group). Conclusions and relevance The intake of a diet with an excessive content of highly available phosphorus may have adverse effects on parameters of kidney function in healthy cats.

Urinary Tamm-Horsfall protein, albumin, vitamin D-binding protein, and retinol-binding protein as early biomarkers of chronic kidney disease in dogs

Proteinuria is a marker and mediator of chronic kidney disease (CKD). In clinical practice, the urinary protein‐to‐creatinine ratio (UP/C) is of limited usefulness, because it indicates only the magnitude of proteinuria and not the origin of the loss (glomerular or tubular). The complete assessment of proteinuria includes quantitative and qualitative evaluations, both of which are required in order to optimize the therapy. In addition to measuring the UP/C, we performed SDS‐PAGE and western blotting to determine the expression of albumin, vitamin D‐binding protein (VDBP), retinol‐binding protein (RBP), and Tamm‐Horsfall protein (THP) in urine samples of 49 dogs: healthy (control) dogs (n = 9); and dogs with CKD (n = 40), stratified by stage. In the dogs with stage 3 or 4 CKD, there was a predominance of tubular proteins. Neither VDBP nor RBP was observed in the urine of the control dogs. Among the dogs with stage 1 or 2 CKD, VDBP and RBP were detected in those without proteinuria or with borderline proteinuria. The expression of urinary albumin was significantly higher in the stage 4 group than in any other group (P ≤ 0.01). In the stage 4 group, urinary THP was either undetectable or lower than in the control group (P ≤ 0.01). In conclusion, urinary VDBP and RBP might act as early markers of kidney injury, and a decrease in urinary THP could be an indicator of CKD progression.

B-mode and Doppler ultrasound of chronic kidney disease in dogs and cats

Ultrasound is the imaging test of choice for renal evaluation, because it provides information about the position, size, shape, internal architecture and hemodynamics of the kidneys without harming the patient. In chronic kidney disease, the main findings observed in B-mode ultrasound images are increased cortical echogenicity, loss of corticomedullary differentiation, reduced renal volume and irregular renal contour, and when these changes are associated, they are indicative of end-stage renal disease. However, the cause of kidney disease cannot be determined by ultrasonography, but must be confirmed by means of biopsy, although the presence of ultrasonographic changes indicative of the end-stage of the disease may contraindicate this procedure. The Doppler ultrasound test complements the ultrasonic B-mode examination and enables the assessment of renal perfusion based on a calculation of the hemodynamic indices, which are increased in cases of chronic kidney lesions, with higher values ​​in the most severe cases. Thus, ultrasound examinations are not only useful in diagnostics but also play an important role in defining the prognosis of patients with chronic kidney disease.

Systolic blood pressure, routine kidney variables and renal ultrasonographic findings in cats naturally infected with feline immunodeficiency virus

Objectives Hypertension is a common cause of proteinuria in HIV-infected people. In cats, feline immunodeficiency virus (FIV) infection appears to be associated with proteinuria. Therefore, the results from systolic blood pressure (SBP) measurements in naturally infected FIV-positive cats were reviewed to assess whether hypertension contributes to the observed proteinuria in these cats. Ultrasonographic findings in FIV-positive cats were reviewed to complete renal assessment and to extend the scant knowledge on renal ultrasonography in cats. Methods Data from client-owned, naturally infected FIV-positive cats were retrospectively reviewed. To obtain a control group, records were reviewed from age-matched, privately owned, FIV-negative cats. Results Data from 91 FIV-infected and 113 control cats were compared. FIV-infected cats showed a significantly lower SBP ( P <0.0001) and significantly fewer FIV-infected cats were hypertensive (⩾160 mmHg) compared with control cats ( P = 0.025). The prevalence of renal azotaemia did not significantly differ between groups, although FIV-infected cats had significantly lower urine specific gravity (USG) ( P = 0.0273) and a higher incidence of USG below 1.035 ( P = 0.043). Urinary protein:creatinine ratio (UPC) was significantly higher in FIV-infected cats ( P = 0.0005) and proteinuria (UPC >0.4) occurred more frequently in FIV-infected cats ( P <0.001). Renal ultrasonography showed abnormalities in 60/91 FIV-infected cats, with hyperechogenic cortices in 39/91 and enlarged kidneys in 31/91. Conclusions and relevance Hypertension can be excluded as a common cause of renal damage leading to proteinuria in FIV-infected cats. Proteinuria and poorly concentrated urine are common in naturally infected FIV-positive cats, in contrast to azotaemia. Clinicians should cautiously interpret ultrasonographic abnormalities as these occur in over half of FIV-infected cats.

Symmetric Dimethylarginine: Improving the Diagnosis and Staging of Chronic Kidney Disease in Small Animals

Chronic kidney disease (CKD) is a common condition in cats and dogs, traditionally diagnosed after substantial loss of kidney function when serum creatinine concentrations increase. Symmetric dimethylarginine (SDMA) is a sensitive circulating kidney biomarker whose concentrations increase earlier than creatinine as glomerular filtration rate decreases. Unlike creatinine SDMA is unaffected by lean body mass. The IDEXX SDMA test introduces a clinically relevant and reliable tool for the diagnosis and management of kidney disease. SDMA has been provisionally incorporated into the International Renal Interest Society guidelines for CKD to aid staging and targeted treatment of early and advanced disease.

Ascending haemorrhagic myelomalacia associated with systemic hypertension in a hyperthyroid cat

CASE SUMMARY

An 8-year-old domestic shorthair neutered male cat was presented with acute onset of paraplegia, absent nociception on the pelvic limbs, tail and perianal area, and a previous history of uncontrolled hyperthyroidism (even after thyroidectomy) and chronic hypertension. The magnetic resonance findings (heterogeneous intramedullary ill-defined area, isointense on T1-weighted and hyperintense on short tau inversion recovery and T2-weighted scans between T12 and L5 spinal cord segments) were consistent with ascending haemorrhagic myelomalacia, which was confirmed by histopathology. It also revealed myelomalacia associated with diffuse arteriolar hyalinosis, similar to the reports found with hypertensive encephalopathy.

RELEVANCE AND NOVEL INFORMATION

Myelomalacia should be considered as a possible outcome in cats with hypertension. Considering that hypertension is a common consequence of hyperthyroidism, emphasis should be given to blood pressure monitoring, especially after treatment of this condition. We describe the histopathological changes occurring in the spinal cord associated with a state of hypertension.

Feline CKD: Diagnosis, staging and screening - what is recommended?

PRACTICAL RELEVANCE

Feline chronic kidney disease (CKD) is frequently encountered by veterinarians. Timely diagnosis and staging may facilitate the initiation of adequate therapy and improve the prognosis for patients.

CLINICAL CHALLENGES

Feline CKD is diagnosed based on the presence of compatible clinical signs and renal azotaemia, which implies that urinalysis (particularly urine specific gravity) is mandatory to confirm the diagnosis. Although the diagnosis of advanced feline CKD and associated complications is usually straightforward, based on complete blood and urine examination, all routine blood and urine tests have their limitations in detecting early CKD. Therefore, diagnosing early or non-azotaemic CKD is much more challenging. Although determination of glomerular filtration rate (GFR) would be ideal to identify early kidney dysfunction, practical limitations hamper its routine use in clinical practice.

PATIENT GROUP

CKD is typically a disease of aged cats, but may affect cats of all ages. Conclusive breed and sex predispositions for feline CKD are not reported.

AUDIENCE

This review is directed at practising veterinarians and provides an overview of the required diagnostic tests, the classification system established by the International Renal Interest Society, and the importance of and possible techniques for early detection of CKD.

EVIDENCE BASE

Staging of cats with CKD is essential as it directs management and provides a prognostic guide. Given that diagnosis at early disease stages is associated with more prolonged survival times, simple, inexpensive and accurate methods for early CKD diagnosis are needed. Techniques currently under investigation include limited sampling strategies to estimate GFR, clearance marker cut-off concentrations to identify cats with low GFR, new indirect GFR markers and urinary biomarkers.

Urinary biomarkers for acute kidney injury in dogs

Routinely, kidney dysfunction and decreased glomerular filtration rate (GFR) are diagnosed by the evaluation of changes in the serum creatinine (SCr) and blood urea nitrogen (BUN) concentrations. However, neither of these tests is sensitive or specific enough for the early diagnosis of impaired kidney function because they are both affected by other renal and nonrenal factors. Furthermore, kidney injury can be present in the absence of kidney dysfunction. Renal reserve enables normal GFR even when nephrons are damaged. Renal biomarkers, especially those present in urine, may be useful for the study of both acute and chronic nephropathies. The aim of this review is to describe the current status of urinary biomarkers as diagnostic tools for kidney injury in dogs with particular focus on acute kidney injury (AKI). The International Renal Interest Society (IRIS) canine AKI grading system and the implementation of urinary biomarkers in this system also are discussed. The discovery of novel urinary biomarkers has emerged from hypotheses about the pathophysiology of kidney injury, but few proteomic urine screening approaches have been described in dogs. Lack of standardization of biomarker assays further complicates the comparison of novel canine urinary biomarker validation results among studies. Future research should focus on novel biomarkers of renal origin and evaluate promising biomarkers in different clinical conditions. Validation of selected urinary biomarkers in the diagnosis of canine kidney diseases must include dogs with both renal and nonrenal diseases to evaluate their sensitivity, specificity as well as their negative and positive predictive values.

Chronic kidney disease in dogs in UK veterinary practices: prevalence, risk factors, and survival

BACKGROUND

The prevalence for chronic kidney disease (CKD) in dogs varies widely (0.05-3.74%). Identified risk factors include advancing age, specific breeds, small body size, and periodontal disease.

HYPOTHESIS/OBJECTIVES

To estimate the prevalence and identify risk factors associated with CKD diagnosis and survival in dogs. Purebred dogs were hypothesized to have higher CKD risk and poorer survival characteristics than crossbred dogs.

ANIMALS

A merged clinical database of 107,214 dogs attending 89 UK veterinary practices over a 2-year period (January 2010-December 2011).

METHODS

A longitudinal study design estimated the apparent prevalence (AP) whereas the true prevalence (TP) was estimated using Bayesian analysis. A nested case-control study design evaluated risk factors. Survival analysis used the Kaplan-Meier survival curve method and multivariable Cox proportional hazards regression modeling.

RESULTS

The CKD AP was 0.21% (95% CI: 0.19-0.24%) and TP was 0.37% (95% posterior credibility interval 0.02-1.44%). Significant risk factors included increasing age, being insured, and certain breeds (Cocker Spaniel, Cavalier King Charles Spaniel). Cardiac disease was a significant comorbid disorder. Significant clinical signs included halitosis, weight loss, polyuria/polydipsia, urinary incontinence, vomiting, decreased appetite, lethargy, and diarrhea. The median survival time from diagnosis was 226 days (95% CI 112-326 days). International Renal Interest Society stage and blood urea nitrogen concentration at diagnosis were significantly associated with hazard of death due to CKD.

CONCLUSIONS AND CLINICAL IMPORTANCE

Chronic kidney disease compromises dog welfare. Increased awareness of CKD risk factors and association of blood biochemistry results with survival time should facilitate diagnosis and optimize case management to improve animal survival and welfare.

Tolerability and efficacy of the intestinal phosphate binder Lantharenol® in cats

Background

Tolerability and efficacy of the intestinal phosphate binder Lantharenol^® (lanthanum carbonate octahydrate) were tested in two prospective, randomized and negative controlled laboratory studies with healthy adult cats fed commercial maintenance diets non-restricted in phosphorus. In the first study, the maximal tolerated dose was determined. Starting from a dose of 0.125 g/kg body weight mixed with the daily feed ration, the dose of Lantharenol^® was doubled every other week until signs of intolerability were observed (N = 10 cats compared to 5 untreated controls). In the second study, the effects of feed supplementation for two weeks with approximately 2, 6, and 20% of the maximal tolerated dose on phosphorus excretion patterns and balance were assessed (N = 8 cats per group).

Results

Lantharenol^® was found to be safe and well tolerated up to the dose of 1 g/kg bodyweight, corresponding to a concentration of 84 g Lantharenol^®/kg complete feed, defined as dry matter with a standard moisture content of 12%. Feed supplementation for two weeks with approximately 2-20% of this dosage (i.e., 1.6, 4.8, and 16 g/kg complete feed) resulted in a shift from urinary to faecal phosphorus excretion. Apparent phosphorus digestibility was dose-dependently reduced compared to the control group fed with diet only (N = 8).

Conclusions

The feed additive was well accepted and tolerated by all cats. Therefore, Lantharenol^® presents a well tolerated and efficacious option to individually tailor restriction of dietary phosphorus as indicated, for instance, in feline chronic kidney disease.

Renal amyloidosis in dogs: a retrospective study of 91 cases with comparison of the disease between Shar-Pei and non-Shar-Pei dogs

BACKGROUND

Renal amyloidosis (RA) is a progressive and fatal renal disease.

HYPOTHESIS

Clinical and pathologic manifestations of RA differ between Chinese Shar-Pei (CSPs) and non-Shar-Pei (NSPs) dogs.

ANIMALS

91 client-owned dogs.

METHODS

Retrospective review of medical records of dogs with a histological diagnosis of RA. Clinical and clinicopathologic data, hospitalization, complications, and outcome were compared between CSPs and NSPs.

RESULTS

Comorbid diseases were present in 64% of all dogs. CSPs were significantly younger compared to NSPs (median, 4.8 years; range: 3.6-17 versus median: 9.0 years; range: 2.4-11.1; P < .0001). The frequency of hypoalbuminemia, the most common biochemical abnormality, was higher in NSPs compared to CSPs (100% versus 64.7%, respectively; P < .001). Median serum creatinine concentration at presentation was 5.5 mg/dL, and was 3-fold higher in CSPs compared to NSPs (P = .005). Increased urine protein : creatinine ratio was present in 96% of all dogs. Nephrotic syndrome was present in 10% of NSPs but not in CSPs. Glomerular amyloid deposition, present in both CSPs (78.6%) and NSPs (95.6%) was most commonly diffuse, global, and severe. Renal medullar amyloidosis was more common in CSPs (100%) compared to NSPs (49.0%, P = .002), as was extrarenal amyloid deposition. The median survival time of all dogs was 5 days (range: 0-443 days). Serum creatinine concentration was significantly and negatively associated with survival (P = .025).

CONCLUSIONS AND CLINICAL RELEVANCE

The clinical and pathologic manifestations of amyloidosis differ between CSPs and NSPs. The survival time observed herein was unexpectedly low, and argues for early surveillance and management of the underlying predisposing conditions.

Development of new canine and feline preventive healthcare guidelines designed to improve pet health

The American Veterinary Medical Association (AVMA) and American Animal Hospital Association (AAHA) have jointly introduced the first Canine and Feline Preventive Healthcare Guidelines. These consensus statements provide veterinarians with a new resource for improving patient care by emphasizing the value and scope of regular pet examinations. The two guidelines provide complete recommendations for comprehensive preventive healthcare programs, published as accessible, single-page documents. The guidelines are based on the subjective-objective-assessment-plan (SOAP) methodology of case management, a proven approach traditionally used with sick or injured patients. This logical and disciplined process is equally applicable to healthy patients and is designed to consistently deliver optimal patient care. The guidelines recommend visits for health examinations on at least an annual basis, recognizing that for many pets, more frequent visits may be appropriate, depending on the individual needs of the patient. The guidelines also provide detailed diagnostic, therapeutic, prevention, and follow up plans, to be accompanied by appropriate documentation. The inclusive content and concise format of the guidelines are designed to maximize their practical value and make them easy to implement.

C-reactive protein concentrations in serum of dogs with naturally occurring renal disease

The current study was undertaken to investigate the relation between serum C-reactive protein (CRP) concentrations and parameters of renal function in dogs with naturally occurring renal disease. Dogs were assigned to groups according to plasma creatinine concentration, urinary protein-to-creatinine ratio (UP/UC), and exogenous plasma creatinine clearance (P-ClCr) rates. Group A (healthy control dogs; n = 8): non-azotemic (plasma creatinine <125 µmol/l) and nonproteinuric (UP/UC <0.2), with P-ClCr rates >90 ml/min/m2; group B (n = 11): non-azotemic, nonproteinuric dogs with reduced P-ClCr rates (50–89 ml/min/m2); group C (n = 7): azotemic, borderline proteinuric dogs (P-ClCr rates: 22–67 ml/min/m2); and group D (n = 6): uremic, proteinuric dogs (not tested for P-ClCr). The serum CRP concentrations were measured via commercial enzyme-linked immunosorbent assay. The CRP concentrations in the clinically healthy dogs (group A) ranged from 2.09 mg/l to 8.60 mg/l (median: 3.21 mg/l). In comparison with dogs of group A, median CRP concentrations were significantly ( P < 0.01) elevated in dogs of group B (17.6 mg/l, range: 17.0–19.2 mg/l), group C (24.8 mg/l, range: 18.0–32.5 mg/l), and group D (59.7 mg/l, range: 17.7–123 mg/l). Serum CRP was significantly related to P-ClCr ( r = –0.83; P < 0.001), plasma creatinine ( r = 0.81; P < 0.001), UP/UC ( r = 0.70; P < 0.001), and leukocytes ( r = 0.49; P < 0.01). The significant relations between serum CRP concentrations and biochemical parameters of kidney function in plasma and urine suggest that a stimulation of the acute phase response is implicated in the pathogenesis of canine renal disease.

The kidney in critically ill small animals

Critically ill animals may have preexisting renal disease or develop acute kidney injury as a consequence of their presenting complaint. Age, concurrent medical therapy, electrolyte and fluid imbalances, and exposure to potential nephrotoxicants are factors that predispose to acute kidney injury. Many risk factors are correctable or manageable, and these should be addressed whenever possible. Measurement of serum creatinine is insensitive for the detection of acute kidney injury, and clinicians should consider assessment of other parameters such as urine output, urinalysis, and urine chemistry results. A stepwise approach for management of acute kidney injury in small animal patients is outlined.

A multicenter retrospective study of 151 renal biopsies in horses

BACKGROUND

Renal biopsies are uncommonly performed in horses and little is known about their diagnostic utility and associated complication rate.

OBJECTIVE

To describe the techniques, the complication rate, risk factors, and histopathology results; as well as evaluate the safety and diagnostic utility of renal biopsy in the horse.

ANIMALS

One hundred and forty-six horses from which 151 renal biopsies were obtained. Animals ranged in age from 48 hours to 30 years.

METHODS

Multicenter retrospective study, with participation of 14 institutions (1983-2009).

RESULTS

Renal biopsy in horses was associated with a similar rate of complications (11.3%) to that occurring in humans and companion animals. Complications were generally associated with hemorrhage or signs of colic, and required treatment in 3% of cases. Fatality rate was low (1/151; 0.7%). Biopsy specimens yielded sufficient tissue for a histopathologic diagnosis in most cases (94%) but diagnoses had only fair (72%) agreement with postmortem findings. Risk factors for complications included biopsy specimens of the left kidney (P = .030), a diagnosis of neoplasia (P = .004), and low urine specific gravity (P = .030). No association with complications was found for age, sex, breed, institution, presenting complaint, other initial clinicopathologic data, biopsy instrument, needle size, or use of ultrasonographic guidance.

CONCLUSIONS AND CLINICAL IMPORTANCE

Renal biopsy in horses has low morbidity and results in a morphological histopathologic diagnosis in 94% of cases. However, this procedure might result in serious complications and should only be used when information obtained would be likely to impact decisions regarding patient management and prognosis.

Case-control study of risk factors associated with feline and canine chronic kidney disease

An age-matched case-control study was initiated to determine the major risk factors associated with CKD in cats and dogs and to determine what clinical signs cat and dog owners observed before their veterinarian diagnosed their pet with CKD. When compared to controls, the feline cases were more likely to have had polydipsia and polyuria in the year before the owners' cats were diagnosed with CKD. In the dogs, increased water intake, increased urination, small size and a recent history of weight loss and bad breath were noticed by the dog owners before veterinary CKD diagnosis. Dog owners recognized abnormal drinking and urination behavior over half a year before their pet's veterinary diagnosis with CKD, and they recognized weight loss almost 4 months before CKD diagnosis. Bad breath was noticed 1.2 years before recognition of CKD by a veterinarian. Given that earlier CKD diagnosis should have been possible in most cases, clinical trials should proceed to measure the efficacy of early interventions.

Acetaminophen induced renal injury via oxidative stress and TNF-alpha production: therapeutic potential of arjunolic acid

Acetaminophen (APAP) causes acute and chronic renal failure. The mechanisms leading to hepatic injury have been extensively studied, but the molecular mechanisms regarding APAP-induced nephro-toxicity are poorly defined. In earlier studies, we have demonstrated that arjunolic acid (AA) possesses protective roles against chemically induced organ pathophysiology. The purpose of the present study was to explore whether AA plays any protective role against APAP induced acute renal toxicity; and if so, what pathways it utilizes for the mechanism of its protective action. Exposure of rats with a nephro-toxic dose of APAP altered a number of biomarkers (like blood urea nitrogen and serum creatinine levels, etc.) related to renal oxidative stress, decreased antioxidant activity, elevated renal tumor necrosis factor-alpha and nitric oxide levels. AA treatment both pre- and post to APAP exposure protected the alteration of these biomarkers, compensated deficits in the antioxidant defense mechanisms, and suppressed lipid peroxidation in renal tissue. Investigating the inherent molecular signaling of this pathophysiology and its protection, we found that the mitochondrial pathway was not activated during APAP-induced cell death as no dissipation of mitochondrial membrane potential or release of cytochrome C was detected in the respective experiments. Our experimental evidence suggests that APAP-induced nephro-toxicity is a caspase-dependent process that involves activation of caspase-9 and caspase-3 in the absence of cytosolic cytochrome C release. These results provide evidence that inhibition of NO overproduction and maintenance of intracellular antioxidant status may play a pivotal role in the protective effects of AA against APAP-induced renal damage. AA represents a potential therapeutic option to protect renal tissue from the detrimental effects of acute acetaminophen overdose.

Interactions between thyroid and kidney function in pathological conditions of these organ systems: a review

Thyroidal status affects kidney function already in the embryonic stage. Thyroid hormones influence general tissue growth as well as tubular functions, electrolyte handling and neural input. Hyper- and hypo-functioning of the thyroid influences mature kidney function indirectly by affecting the cardiovascular system and the renal blood flow, and directly by affecting glomerular filtration, electrolyte pumps, the secretory and absorptive capacity of the tubuli, and the structure of the kidney. Hyperthyroidism accelerates several physiologic processes, a fact which is reflected in the decreased systemic vascular resistance, increased cardiac output (CO), increased renal blood flow (RBF), hypertrophic and hyperplastic tubuli, and increased glomerular filtration rate (GFR). Renal failure can progress due to glomerulosclerosis, proteinuria and oxidative stress. Hypothyroidism has a more negative influence on kidney function. Peripheral vascular resistance is increased with intrarenal vasoconstriction, and CO is decreased, causing decreased RBF. The influence on the different tubular functions is modest, although the transport capacity is below normal. The GFR is decreased up to 40% in hypothyroid humans. Despite the negative influences on glomerular and tubular kidney function, a hypothyroid state has been described as beneficial in kidney disease. Kidney disease is associated with decreased thyroid hormone concentrations caused by central effects and by changes in peripheral hormone metabolism and thyroid hormone binding proteins. Geriatric cats form an animal model of disease because both hyperthyroidism and chronic kidney disease (CKD) have high prevalence among them, and the link between thyroid and kidney affects the evaluation of clinical wellbeing and the possible treatment options.

Short- and long-term follow-up of glomerular and tubular renal markers of kidney function in hyperthyroid cats after treatment with radioiodine

Hyperthyroidism can mask co-existing chronic kidney disease (CKD). Previous studies showed that post-treatment renal azotemia can be predicted by pre-treatment assessment of glomerular filtration rate (GFR). We hypothesized that treatment of hyperthyroidism may have different effects on glomerular and tubular function and these changes might be predicted by additional pre-treatment variables than GFR. Serum total T4 (TT4), creatinine and blood urea nitrogen (BUN), blood pressure (BP), body weight (BW), GFR, urine specific gravity (USG), urinary protein/creatinine ratio (UPC) and retinol binding protein/creatinine ratio (uRBP/c) were evaluated before and 1, 4, 12 and 24 weeks post-treatment with radioiodine ((131)I) in 21 non-azotemic hyperthyroid cats. Cats were divided 24 weeks post-treatment into group A (normal kidney function, n=16) and group B (impaired kidney function, n=5). Serum TT4, GFR, UPC and uRBP/c decreased significantly after treatment for the complete group and group A (P<0.05), although GFR and uRBP/c did not change in group B. Serum creatinine and BW increased significantly from 1 week after treatment (P<0.05). There was no change in BUN, USG or BP. Pre-treatment serum TT4, GFR and USG differed significantly between group A and B (P<0.05). GFR at 4 weeks after treatment and maximum decrease in GFR could be partially predicted by a formula using pre-treatment GFR, serum TT4, serum creatinine, BUN and/or USG. Significant changes in kidney function occur within 4 weeks post-treatment and none thereafter. Pre-treatment measurement of GFR, USG and serum TT4 can have possible predictive value regarding the development of post-treatment renal azotemia.