Assessment of urinary bladder volume in dogs by use of linear ultrasonographic measurements.

OBJECTIVE

To evaluate accuracy of formulas derived from linear ultrasonographic measurements and used in human beings to assess urinary bladder volume as a method of estimating bladder volume in dogs and to test reproducibility of ultrasonographic measurements of linear bladder dimensions.

ANIMALS

64 live dogs (for bladder volume determination) and 31 fresh canine cadavers (for ultrasonographic assessment of reproducibility of measurements).

PROCEDURE

Maximal length, longitudinal and transverse depth (DL and DT), and width were measured from the maximal longitudinal and transverse images. Bladder volume was estimated, using 6 formulas, and calculated volumes were compared statistically with the actual volume obtained by catheterization, using paired nonparametric tests. Reproducibility of bladder dimensions was investigated by measuring length, DL, DT, and width 3 times from each image of section. Measurements of depth (DL and DT) also were compared.

RESULTS

Calculations of bladder volume from linear dimensions, using a formula described for use in human beings, gave a satisfactory indication of actual bladder volume; the median difference between actual and calculated volumes was only 5 ml. Bladder volume estimations were less accurate when large-volume bladders were measured. Matching between repeated measurements was significant (P < 0.005 for longitudinal bladder length and P < 0.0001 for bladder depth and width). Measurements of DL and DT were significantly (P < 0.01) different, with DL greater than DT.

CONCLUSIONS

Ultrasonographic assessment of bladder volume in dogs by application of the formula is sufficiently accurate for most clinical purposes.

CLINICAL RELEVANCE

Ultrasonography would be a useful method of estimating bladder volume in dogs with severe obstruction or dysfunctional voiding of urine.