Procedure—Each of the cattle was restrained in a
standing position. Height of the second lumbar vertebra's
transverse process (2LTP) and humeral tuberosity
(HT) on the right side as well as abdominal girth
(AG) were measured in each animal, and body condition
score (BCS) was ascertained. Skin caudal to the
first lumbar spinous process was aseptically prepared,
and anesthetic was injected. After inserting a
16-gauge 120-mm Tuohy needle in the ligamentum
flavum, a calibrated pressure transducer was connected
to the needle. Then, the needle was introduced
into the epidural space, and epidural pressure
Results—Mean ± SD residual epidural pressure of
heifers (–9.3 ± 3.3 mm Hg) was significantly higher than
that of lactating (–17.4 ± 5.5 mm Hg) or nonlactating
(–14.5 ± 2.4 mm Hg) cows. Stepwise regression of 5
variables revealed that only the difference in height
between 2LTP and HT (2LTP – HT) in heifers and only
BCS in lactating cows were significantly correlated with
residual epidural pressure. For all cattle, the optimal
equation (R2 = 0.47) describing the relationship was
y = –12.7 + 6.3x1 – 0.4x2 – 0.1x3, where y is epidural
pressure, x1 is BCS, x2 is 2LTP – HT, and x3 is age.
Conclusions and Clinical Relevance—Negative
epidural pressure was detected in standing cattle.
Growth, maturity, and pregnancy affect epidural pressure
in cattle. (Am J Vet Res 2002;63:954–957)
Objective—To compare the use of a single-sample method involving IV administration of iodixanol with a multisample method involving inulin for the estimation of glomerular filtration rate (GFR) in cats.
Animals—24 cats, including 15 healthy cats and 9 cats with naturally occurring renal diseases.
Procedures—Each cat was coadministered iodixanol (a nonionic contrast medium; dose providing 40 mg of I/kg) and inulin (50 mg/kg), IV, and blood samples were collected 60, 90, and 120 minutes later. Serum iodixanol and inulin concentrations were determined by means of high-performance liquid chromatography and colorimetry, respectively. Serum urea nitrogen and creatinine concentrations were also measured.
Results—Analysis of the data from healthy cats and cats with naturally occurring renal diseases revealed an excellent correlation between GFR values estimated by the multisample and single-sample methods with iodixanol. Likewise, GFR values estimated from the single-sample method with iodixanol were closely correlated with those calculated from the multisample method with inulin.
Conclusions and Clinical Relevance—For estimation of GFR in cats, use of a single-sample method with iodixanol, instead of a multisample procedure, may be an expedient tool in both clinical and research settings because of its benefits to patient well-being as a result of reduced stress associated with blood sample collection.