Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 9
Biopsy
needle
Left
kidney
Right
flank
Clinician's
hand in
rectum
Figure 9.3 Technique for biopsy of the
left kidney. See text for details.
with great caution in animals which are
already dehydrated, and should not be performed
in uraemic patients.
Fractional clearance of electrolytes
In cattle, creatinine is excreted by glomerular filtration.
It is neither secreted or reabsorbed by the renal
tubules following glomerular filtration. An index
of renal tubular function for an electrolyte can be
obtained by measuring the fractional clearance. The
fractional clearance of an electrolyte A can be obtained
by concurrently measuring the concentration
of creatinine in serum (S C
) and in urine (U C
) and the
concentration of electrolyte A in serum (S A
) and in
urine (U A
). The percentage clearance is given by
Percentage clearance of electrolyte A=
((U A
/S A
)/(U C
/S C
)) ¥ 100
Normal mean percentage clearance values in heifers
11 to 14 months old have been reported as follows:
sodium, 1.97%; potassium, 49.3%; chloride 3.16%;
phosphorus, 15.6%; and calcium, 1.38%.
Renal biopsy
A needle biopsy of left kidney can be taken through
the right sublumbar fossa of the animal, preferably
guided by ultrasound. The left kidney is pushed towards
the right abdominal wall by manual pressure
exerted per rectum. Using strict aseptic precautions, a
Tru-cut 14 BWG (2.00 mm) biopsy needle of length
15.2 cm is guided through the abdominal wall and
into the kidney (Fig. 9.3).
History of the case
The general history of the case will have been considered
at an earlier stage in the process of diagnosis.
Although some diseases of the renal system such
as pyelonephritis are sporadic, other conditions
118