.5=<6=72):520$6., Abstract. Material and Methods. Key words: dog, gallbladder volume, method of estimation. Bull Vet Inst Pulawy 48, , 2004

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1 Bull Vet Inst Pulawy 48, , 2004 $&&85$&<2)(67,0$7,212)&$1,1(*$//%/$''(5 92/80()52021(0($685(0(17.5=<6=72):520$6., Department of Animal Physiology, Faculty of Veterinary Medicine 8QLYHUVLW\RI$JULFXOWXUH:URFáDZ3RODQG Received for publication June 06, Abstract The aim of this work was to develop the rapid and precise method of estimation of gallbladder volume in dogs. For this purpose 87 experiments were performed in nine fasted dogs. The ultrasonographical images of gallbladder longitudinal and transverse positions were obtained every 10 min during the period 1-6 h and length, width and height of the gallbladder were measured. Then, the length-height and widthheight mean correlation coefficients were calculated. Three groups of the representative results (during submaximal relaxation, moderate contraction and maximal contraction) were selected and the gallbladder volumes were estimated using the original data (length, width and height). These results were compared with the calculation of gallbladder volumes from the same data when only one original measurement (length) was used with both mean coefficients, utilizing the ellipsoid formula. Two other formulas of gallbladder volume calculation (cone and cylinder) were also presented as the examples of the possibility of application of various formulas selected in dependence on gallbladder shape. The results indicate that the accuracy of estimation of gallbladder volume in dogs from one direct measurement is sufficient when the proper coefficient and calculation method are used. Thus, the proposed method is rapid and accurate and seems to be useful in the veterinary practice. Key words: dog, gallbladder volume, method of estimation. There are several diseases requiring gallbladder examination in the dog (3). The ultrasonography is the first-choice method to assess gallbladder function and both structural and functional alterations can be detected or studied (8, 9). However, the functional studies can be time-consuming since they often require mathematical elaboration of the results. Consequently, the necessary time to evaluate gallbladder function can be too long in some clinical situations and the complicated procedures can hamper the progress in this area. That is why there is need for the simplification of the methods estimating precisely the gallbladder volume and contraction and for shortening time of their utilization. Thus, the aim of this study was to elaborate more rapid and precise method estimating gallbladder volume based on only one direct ultrasonographical measurement of the length of gallbladder. Material and Methods Nine male mongrel dogs weighing 14.1±3.3 kg were used. Animals were fasted overnight before the experiments. Eighty-seven experiments lasting 1-6 h were performed before and after feeding with four different meals to obtain the broad spectrum of gallbladder sizes: 1) large meal containing dry food ')3HGLJUHH0DVWHUIRRGV3ROVND.R*XV]NL3DUFHO g/kg, canned food (CF, Pedigree, Waltham 0DVWHUIRRGV 3ROVND.R*XV]NL 3DUFHO JNJ DQG sunflower oil (SO, Kruszwica - Cereol Budapest) 2 g/kg, 2) moderate meal 1 containing DF 20 g/kg and tap water 40 ml/kg, 3) moderate meal 2 containing CF 20 g/kg and 4) small meal containing DF 5 g/kg, CF 5 g/kg and SO 1 g/kg of body weight. Drinking water was not limited. However, dogs did not drink before and during experiments. Experiments. Ultrasonographical imaging was performed using the apparatus Hitachi EUB 405 (Tokyo, Japan) with linear-convex-type transducer of 5 MHz frequency and Videoprinter P 40 U Mitsubishi (Tokyo, Japan). The probe was adhibited to the skin of the right lateral region of the trunk. Skin was deprived of hair and covered with ultrasonographical gel. After visualization of the maximal gallbladder longitudinal contour and the length measurement on the top of inspiration, the probe was immediately turned 90 o to obtain the maximal transverse image. Then, the width and height were measured on the top of inspiration, using the electronic calliper, and printed. The measurements of length, width and height of the gallbladder were performed every 10 min. Calculations. The results were divided into 10 groups depending on the degree of gallbladder contraction (maximal gallbladder relaxation as 100% of the given animal, 90-99, 80-89, 70-79, 60-69, 50-59, 40-49, 30-39, and below 20% of maximal gallbladder contraction). For further comparison, the relevant values of length, width and height were also multiplied. Then,

2 160 two mean coefficients (length:height and width:height) were calculated. The gallbladder volumes were estimated using the ellipsoid method (4, 10). The selected representative data were additionally elaborated to estimate the gallbladder volumes with three methods i.e. the classical ellipsoid method, the sum-of-cylinder method (5) and the proposed method using one original measurement. For the proposed method the ellipsoid IRUPXOD 9 ŒDEF RU 9 DEF ZKHUH 9 ± estimated gallbladder volume, a length of gallbladder, b width of gallbladder and c height of gallbladder was modified into the formula V = 0.523a (a/x) 2 y where x first coefficient (length:height) and y second coefficient (width:height). For atypical gallbladder shapes the adapted formulas approximating gallbladder shape to the cone (2) or the cylinder (11) are proposed. The formula described by Cano et al. (2) can be applied when gallbladder shape is rather thin while in the reversed situation the cylinder formula should be used. The original formula of Cano et allv9 ŒDU 2 where a gallbladder length, r ½ of gallbladder height. This should be supplemented with asymmetry coefficient (width:height) to be finally applied in the form: V = ŒD>D[@ 2 y where a - length of gallbladder, x and y mean calculated coefficients. The formula approximating gallbladder shape to the regular cylinder LV9 ŒU 2 h where r is in this case ½ of gallbladder height and h is the length of gallbladder. After the introduction of asymmetry correction, the final formula approximating gallbladder shape to the cylinder is V = ŒK>K[@ 2 y where x and y are both mean calculated coefficients. Afterwards, the original results were compared with the proposed method estimating gallbladder volume from one measurement using the ellipsoid formula. Statistical analysis was performed where appropriate using of the Student t-test for paired values that was preceded by analysis of variance (12). Results Along with the decrease of gallbladder volumes after feeding, the length, width and height of the gallbladder proportionally decreased in subsequent groups (Table 1). In the last few groups these results were significantly lower than in the group of maximal gallbladder relaxation. The first correlation coefficient (length:height) values increased parallel to the decrease of gallbladder volume while the second correlation coefficient (width:height) slightly decreased (Table 1). From these data, the mean coefficients for submaximal gallbladder relaxation, moderate, and maximal gallbladder contraction values were calculated for further comparisons (Table 2). Table 1 The length:height and width:height coefficients of gallbladder sizes in dependence on the per cent of gallbladder contraction Maximal 0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-70% 70-80% >80% relaxation n = Length mean a b c (a) ±S.D Width mean a a a b c (b) ±S.D Height mean a b b (c) ±S.D Product mean a a b c c 7607 c (abc) ±S.D Ellipsoid mean a a 9.42 b 6.83 c 5.54 c 3.98 c formula ±S.D a : c mean b : c mean Length, width, height and their product are expressed in mm, gallbladder volume (ellipsoid method) in ml. Other explanations, see section Material and Methods.

3 161 Table 2 The raw data and statistical analysis of canine gallbladder sizes during gallbladder relaxation and during moderate and severe contractions. Gallbladder volumes were calculated with ellipsoid method (Ellips.), sum-of-cylinder method (S.O.C.) and using only one measurement (length) with both calculated coefficients Gb actual sizes Actual Calculated Actual gb vol. Calculated coefficients coefficients gb vol Dogs a b c abc a:c b:c a:c b:c Ellips. S.O.C. I mean ±S.D II mean a a a 7.15 a 7.85 ±S.D III mean 37.3 a 14.8 b 12.1 b 6889 c c 3.42 c 4.27 a ±S.D I relaxation, II moderate contraction, III severe contraction. Other explanations as in Table 1. The raw representative data for each dog were also selected and presented in three panels (panel I submaximal relaxation, panel II moderate contraction, panel III maximal contraction). For these data the real coefficients were also calculated and compared with mean coefficients (the compared values were similar). There were no significant differences between the real coefficient values between the panels while the gallbladder sizes and volumes calculated with three various methods (the ellipsoid method, sum-of-cylinder method and the proposed method with one measure including two coefficients) differed significantly, especially between panel I and panel III (Table 2). There were rather no marked differences between the gallbladder volumes estimated with three various methods. However, some data were different especially when the length:height coefficient value was below 2.0 or above 3.5 (Table 2). In the proposed method the ellipsoid formula was applied since the gallbladder shapes were mostly identified to be typical. For atypical

4 162 gallbladder shapes, when the length:height coefficient is well below 2 or above 3.5, the use of two other formulas, estimating gallbladder shape to the cone or cylinder, respectively, can be suggested. Discussion As it was demonstrated in this study, the proposed method estimating gallbladder volume based on one direct measurement of the length of gallbladder exhibits satisfactory precision to be applied in all these situations where the assessment of gallbladder function should be more rapid and simple. The accuracy of this method can be even greater than that of the videly accepted and applied ellipsoid method (4, 7) since the former method is based only upon one gallbladder parameter. When the new method is applied, it is recommended to select the proper formula depending on gallbladder shape. Gallbladder shape can differ much in the dog (10). When the shape resembles the ellipsoid or the sphere, the ellipsoid method is recommended. When gallbladder is thiner the use of method of cone (2) is suggested. When the gallbladder is rather thick and exhibits the atypical shape, the method of cylinder (11) can provide more accurate results. The proper coefficient depending on the actual degree of contraction should also be selected. When it is impossible to assess, the uniform coefficient (for moderate contraction) should be used to minimize the inaccuracy of final result. Comparison with other methods showed that the method estimating canine gallbladder volume from one measurement is accurate and possible to use in various contractile states of gallbladder. However, it is rather not applicable in other species in which the proper coefficients should be first calculated. Critical tables of estimated gallbladder volumes may further simplify the calculation procedure. References volume determinations. J Clin Ultrasound 1993, 21, Cano N., Cicero F., Ranieri F., Martin J., dicostanzo J.: Ultrasonographic study of gallbladder motility during total parenteral nutrition. Gastroenterology 1986, 91, Center S.A.: Diseases of the gallbladder and biliary tree. In: Strombeck s Small Animal Gastroenterology. edited by W. G. Guilford, S. A. Center, D. R. Strombeck, D. A. Williams, D. J. Meyer (Philadelphia, W. B. Saunders Co.) 1996, pp Dodds W. J., Groh W. J., Darweesh R. M. A., Lawson T. L., Kishk S. M. A., Kern M. K.: Sonographic measurement of gallbladder volume. AJR 1985, 145, Everson G. T., Braverman D. Z., Johnson M. L., Kern F.: A critical evaluation of real time ultrasonography for the study of gallbladder volume and contraction. Gastroenterology 1980, 79, Finn-Bodner S. T., Park R. D., Tyler J. W., Twedt D. C., Curtis C. R.: Ultrasonographic determination, in vivo and in vitro, of canine gallbladder volume, using four volumetric formulas and stepwise-regression models. Am J Vet Res 1993, 54, Jonderko K., Ferré J.-P., Buéno L.: Real-time ultrasonography as a noninvasive tool for the examination of canine gallbladder emptying. A validation study. J Pharmacol Toxicol Meth 1992, 27, Lamb C. R.: Ultrasonography of the liver and biliary tract. In: Problems in Veterinary Medicine, edited by W. J. Kay, N. O. Brown (Philadelphia, J. B. Lippincott Co.), 3, 1991, pp Mittal R. K., Liu J.: Ultrasonography. In Schuster Atlas of Gastrointestinal Motility, edited by M. M. Schuster, M. D. Crowell, K. L. Koch (Hamilton, BC Decker Inc.) 2002, pp RPDVNL.:6LHPELHGD-9DOLGDWLRQRIWKHPHWKRGV estimating gallbladder volume. Bull Vet Inst Pulawy 2002, 46, RPDVNL. (YDOXDWLRQ RI WKH PHWKRGV XVHG IRU WKH estimation of gallbladder volume. Ultrason Pol 2003, No. 13, Snedecor G. W., Cochran W. G.: Statistical Methods. The Iowa State University Press, Ames IO Andersen I.B., Monrad H., Gronvall S., Hojgaard L.: In vitro and in vivo accuracy of sonographic gallbladder

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