Kidney function investigations in veterinary medicine are traditionally based on blood analysis (blood urea nitrogen (BUN) and serum creatinine concentration) and / or urinalysis (urine specific gravity, protein-to-creatinine ratio or fractional excretion). Morphologic information is usually obtained by abdominal radiography or ultrasonography. However, when more specific information on the functionality of the kidneys is needed, nuclear medicine offers various tracers that specifically represent glomerular filtration rate, effective renal plasma flow or functional renal mass, sometimes combining functional and morphologic data. These procedures can be based on blood sampling techniques (non-imaging methods), or data can be obtained using a gamma-camera (imaging methods). The most commonly used radionuclides for the examination of kidney function in small animal medicine are discussed in this review.

Kidney function investigations in veterinary medicine are traditionally based on blood analysis (blood urea nitrogen (BUN) and serum creatinine concentration) and / or urinalysis (urine specific gravity, proteinto-creatinine ratio or fractional excretion). Morphologic information is usually obtained by abdominal radiography or ultrasonography. However, when more specific information on the functionality of the kidneys is needed, nuclear medicine offers various tracers that specifically represent glomerular filtration rate, effective renal plasma flow or functional renal mass, sometimes combining functional and morphologic data. These procedures can be based on blood sampling techniques (non-imaging methods), or data can be obtained using a gamma-camera (imaging methods). The most commonly used radionuclides for the examination of kidney function in small animal medicine are discussed in this review. SAMENVATTING Wanneer de nierfunctie bij dieren moet bepaald worden, wordt er gewoonlijk een bloedonderzoek uitgevoerd (voor de bepaling van de ureum- en serum/creatinineconcentratie). Het bloedonderzoek wordt vaak gecombineerd met een urineonderzoek (voor de bepaling van het urinaire soortelijke gewicht, de urinaire eiwit/creatinineratio of fractionele excretie). Morfologische informatie wordt verkregen via de gebruikelijke beeldvormingstechnieken, zoals abdominale radiografie of echografie. Indien er echter meer specifieke informatie nodig is over de nierfunctie, kunnen renale nucleaire merkers gebruikt worden. Afhankelijk van de gebruikte tracer bekomt men informatie over de glomerulaire filtratiesnelheid (GFR), de renale doorbloeding (ERPF) of de hoeveelheid functionele niermassa. Sommige van deze tracers geven bovendien zowel morfologische als functionele informatie. Sommige onderzoeken zijn gebaseerd op een techniek met bloedstalen (niet-beeldvormend), terwijl men bij andere onderzoeken gebruik maakt van een gammacamera (beeldvormend). In dit overzichtsartikel worden de meest gebruikte merkers voor nierfunctieonderzoek bij kleine huisdieren besproken.

BACKGROUND Chronic kidney failure is frequently seen in middle-aged and elderly cats. 51Chromium-ethylene diaminic tetraacetic acid (51Cr-EDTA) clearance and single blood sample (SBS) method are used in several species to estimate the glomerular filtration rate (GFR). HYPOTHESIS The hypothesis of this study was that 51Cr-EDTA clearance could be determined using an SBS method in normal and hyperthyroid cats. ANIMALS Forty-six cats were included in this study, with an average age of 9.5 years. Of these cats, 27 had hyperthyroidism; 19 were healthy. METHODS After IV injection of 51Cr-EDTA (average dose: 4.25 MBq), 7 blood samples were obtained between 5 and 240 minutes. Reference clearance was calculated in mL/min and mL/min/kg body weight, using a 2-compartment model. Optimal time for clearance measurement with SBS was then determined by systematically comparing each individual plasma concentration to the reference multisample clearance. RESULTS The average reference plasma clearance of 51Cr-EDTA for all cats was 14.9 mL/min (3.7 mL/min/kg). The clearance in hyperthyroid cats averaged 16.4 mL/min (4.3 mL/min/kg) and in normal cats averaged 10.3 mL/min (2.4 mL/min/kg). The optimal time for the SBS was 48 minutes after injection of tracer 51Cr-EDTA (R2= 0.9414), giving the following converting equation: clearance = (0.0066 x DV48 minutes) - 0.9277 (in mL/min). CONCLUSIONS AND CLINICAL IMPORTANCE In this study, the single sample 51Cr-EDTA clearance method was used to estimate the global GFR in cats. The method identified differences in clearance between normal and hyperthyroid cats. The optimal time for an SBS was 48 minutes.

BACKGROUND:While the value of the single blood sample (SBS) method for estimating 51Cr-EDTA plasma clearance has been repeatedly demonstrated, some nuclear medicine physicians are still reluctant to use it because of the lack of quality control parameters. PURPOSE:To present a post-test quality control procedure for the SBS technique in children. METHODS:In addition to the SBS clearance calculated using the specific paediatric SBS method, three artificial slope intercept (ASI) method clearances were calculated by assuming the distribution volume as, respectively, 20%, 25% and 30% of body weight. By dividing the injected activity by the distributional volume, the initial plasma concentrations (A0,30%, A0,25% and A0,20%) were calculated. Using these A0 values and the available single sample, ASI clearances were calculated by using the classical slope-intercept method. The working hypothesis of this approach was as follows. In the absence of significant errors, the three ASI clearance values should be close to that of the SBS method. This hypothesis has been tested using both simulated and patients' data. RESULTS:The results of the simulated study showed that an error in the injected dose produced variable differences between SBS and ASI clearances depending on the clearance values. The effect of an error on the plasma sample also varied as a function of the clearance values. The analysis of patient data revealed that the ASI approach allowed the identification of patients in whom the classical slope-intercept method suggested the presence of a possible error. CONCLUSION:A post-test quality control procedure for the SBS GFR measurement is presented. When the SBS clearance shows a difference with the ASI method (> 10 ml . min(-1) per 1.73 m2), the presence of an error is highly probable. A smaller difference, however, does not exclude erroneous data.

The serotonergic and dopaminergic systems are involved in a wide range of emotional and behavioral aspects of animals and humans and are involved in many neuropsychiatric disorders. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are designed to block the 5-HT transporter (SERT), thereby increasing the available 5-HT in the brain. Functional imaging with specific SERT and dopamine transporter (DAT) ligands contributes to the study of the SSRI-transporter interaction.First, we evaluated the feasibility of a canine model in the study of the SERT and DAT with the radioligands [I-123]-beta-CIT and [I-123]-FP-CIT as well as single-photon emission computed tomography imaging. Second, we studied the effect of SSRIs (sertraline, citalopram and escitalopram) on the SERT and DAT in two dogs.The position of the canine model in the study of the SERT and DAT is discussed and compared with other animal models. (c) 2006 Elsevier Inc. All rights reserved.

These guidelines have been adopted by the British Nuclear Medicine Society.

Single blood sample methods are widely used for the estimation of the glomerular filtration rate, but the methods recommended for adults are not the same as those for children. The question arises, therefore, as to which method should be used in an adolescent or young adult. The aim of this study was to compare the performance of two methods, a specific paediatric converting equation and an adult algorithm, in a group of adolescent and young adult patients. From a large database of Cr-51-ethylenediaminetetraacetic acid (Cr-51-EDTA) renal clearance determinations using the two blood sample method, 598 patients, aged 1 week to 90 years, were selected. The results of the Cr-51-EDTA slope intercept clearance of the two blood sample method were used as reference. Using the paediatric algorithm, no bias was observed until the age of 40 years. Then, an increasing positive bias occurred. The standard deviation of the difference was generally less than 4 ml/min until the age of 25 years and increased gradually to reach 7 ml/min at the age of 80 years. Using the Christensen and Groth adult algorithm, the best results were observed in patients older than 50 years. With the exception of children aged less than 5 years, no systematic bias was observed. The standard deviation, however, increased gradually and reached a value of around 8 ml/min in young children. For individuals aged 15-25 years, the mean of the difference between the paediatric algorithm and the slope intercept method was -1.1 ml/min, with a standard deviation of the difference of 3.3 ml/min. For the adult algorithm, the mean of the difference was 0.3 ml/ min, with a standard deviation of the difference of 77 ml/ min. It can be concluded that, for individuals aged 15-25 years, both methods performed correctly. In this series, the paediatric method gave better results than the adult algorithm, and its use is therefore recommended. (C) 2004 Lippincott Williams Wilkins