Excretion of [3H]prednisolone in clinically normal and experimentally infected bovine udders


Geleta, J.N.; Shimoda, W.; Mercer, H.D.

American Journal of Veterinary Research 45(8): 1576-1581

1984


The excretion rate of [3H]prednisolone from clinically normal and experimentally infected udders of 10 lactat- ing cows was studied. Each quarter of 6 cows was injected with a single dose of [3H]prednisolone mixed with non-radioactive prednisolone equivalent to 10 mg in 10 ml of peanut oil base. Each of the remaining 4 cows was given 40 mg of nonradioactive prednisolone and [3H]prednisolone in 60% ethanol Iv. Control and postadministration samples of blood, milk, and urine were examined for radio- activity. The effects of [3H]prednisolone were evaluated in the same cows, first in clinically normal udders, then 2 weeks later in udders experimentally infected with Streptococcus agalactiae. Absorption and elimination of prednisolone were the same before and after induced infection. Within 3 hours after intramammary injection, 95% of the labeled prednisolone was absorbed systemically,<5% of this dose was recovered in milk, and 29% was excreted in urine. After iv injection of [3H]prednisolone,<0.2% of the total radioactivity was recovered in milk and<46% was ex- creted in urine. Clinical mastitis induced by S. agalactiae was moderate. Circulating blood leukocytes and somatic cells in the milk of normal cows remained essentially unchanged. The leukocyte response to induced infection was rapid in blood and milk. Large numbers of leukocytes were noticed in the milk and a severe leukopenia occurred. Prednisolone treatment did not alter the number of somatic cells in milk or reduce the inflammatory response of experimentally infected cows.

Excretion
of
[
3
H]prednisolone
in
clinically
normal
and
experimentally
infected
bovine
udders
J.
N.
Geleta,
DVM,
MS;
Wilbert
Shimoda,
MS;
H.
Dwight
Mercer,
DVM,
PhD
SUMMARY
The
excretion
rate
of
[
3
H]prednisolone
from
clinically
normal
and
experimentally
infected
udders
of
10
lactat-
ing
cows
was
studied.
Each
quarter
of
6
cows
was
injected
with
a
single
dose
of
[
3
H]prednisolone
mixed
with
non-
radioactive
prednisolone
equivalent
to
10
mg
in
10
ml
of
peanut
oil
base.
Each
of
the
remaining
4
cows
was
given
40
mg
of
nonradioactive
prednisolone
and
[
3
I-I]prednisolone
in
60%
ethanol
iv.
Control
and
postadministration
sam-
ples
of
blood,
milk,
and
urine
were
examined
for
radio-
activity.
The
effects
of
[
3
H]prednisolone
were
evaluated
in
the
same
cows,
first
in
clinically
normal
udders,
then
2
weeks
later
in
udders
experimentally
infected
with
Streptococcus
agalactiae.
Absorption
and
elimination
of
prednisolone
were
the
same
before
and
after
induced
infection.
Within
3
hours
after
intramammary
injection,
95%
of
the
labeled
pred-
nisolone
was
absorbed
systemically,
<
5%
of
this
dose
was
recovered
in
milk,
and
29%
was
excreted
in
urine.
After
Iv
injection
of
[
3
H]prednisolone,
<
0.2%
of
the
total
ra-
dioactivity
was
recovered
in
milk
and
<
46%
was
ex-
creted
in
urine.
Clinical
mastitis
induced
by
S
agalactiae
was
moder-
ate.
Circulating
blood
leukocytes
and
somatic
cells
in
the
milk
of
normal
cows
remained
essentially
unchanged.
The
leukocyte
response
to
induced
infection
was
rapid
in
blood
and
milk.
Large
numbers
of
leukocytes
were
noticed
in
the
milk
and
a
severe
leukopenia
occurred.
Prednisolone
treatment
did
not
alter
the
number
of
somatic
cells
in
milk
or
reduce
the
inflammatory
response
of
experimen-
tally
infected
cows.
Corticosteroids
have
been
used
for
many
years
as
a
sup-
plement
to
standard
antibiotic
therapy
in
the
treatment
of
bovine
mastitis.
In
general,
2
rationales
support
the
incorporation
of
steroids
in
intramammary
preparations:
(i)
prevention
or
diminution
of
the
clinical
signs
of
in-
Received
for
publication
Apr
7,
1983.
From
the
Division
of
Veterinary
Medical
Research,
Bureau
of
Veterinary
Med-
icine,
Food
and
Drug
Administration,
Department
of
Health
and
Human
Services,
Agricultural
Research
Center,
Beltsville,
MD
20705
(Geleta,
Shimoda);
and
the
College
of
Veterinary
Medicine,
Mississippi
State
University,
Drawer
V,
Missis-
sippi
State,
MS
39762
(Mercer).
Mr.
Shimoda's
present
address
is
Animal
Drug
Research
Center,
Food
and
Drug
Administration,
500
US
Customs
House,
Denver,
CO
80202.
The
authors
thank
Dorothy
W.
Pocurull
for
assistance
with
bacteriologic
pro-
cedures,
Patricia
E.
Long
for
leukocyte
and
somatic
cell
determinations,
and
David
H.
Showalter
for
computer
and
statistical
analysis.
flammation
induced
by
a
mildly
irritating
product
or
ve-
hicle
and
(ii)
reduction
of
the
inflammatory
response
and
potential
tissue
damage
in
acute
clinical
mastitis.
Exten-
sive
use
of
corticosteroids
in
the
treatment
of
mastitis
have
attracted
only
a
few
reports
of
effects
in
local
intra-
mammary
therapy.'
Prednisone
and
prednisone
acetate
produced
marked
anti-inflammatory
effects,
a
rapid
reduction
in
leukocyte
counts
in
affected
quarters,
and
a
faster
return
to
normal
when
used
alone
or
in
conjunction
with
antibiotics.'
In
contrast,
prednisone
neither
hastened
recovery
nor
af-
fected
leukocyte
counts
when
an
antibiotic
ointment
with
or
without
4.5
mg
of
prednisone
acetate
was
injected
into
62
mastitic
quarters.'
Swarbrick
could
not
show
an
advantage
when
10
mg
of
betamethasone,
50
mg
of
prednisone,
or
50
mg
of
pred-
nisone
trimethyl
acetate
was
added
to
an
aqueous
preparation
of
oxytetracycline.
Administration
of
corti-
sol:corticosterone
at
a
ratio
of
8:1
for
several
consecutive
days
had
little
effect
on
the
concentration
of
leukocytes
in
milk.'
In
a
study'
using
Aerobacter
aerogenes
to
induce
mastitis,
large
doses
of
9a-fluoroprednisolone
acetate
in-
jected
into
mammary
glands
or
given
IM
failed
to
inhibit
or
delay
infiltration
of
leukocytes
into
mammary
quar-
ters
exposed
to
coliform
organisms.
9a-Fluoropredniso-
lone
acetate
(5
or
10
mg)
markedly
altered
numbers
of
blood
leukocytes,
but
had
little
effect
on
the
number
of
somatic
cells
in
milk.'
Investigations
in
cattle
and
dogs
indicated
that
most
corticosteroids
are
excreted
in
the
urine
and
feces.
Krzeminski
et
al"
injected
methylprednisolone
into
ud-
ders
of
dairy
cows
but
were
unable
to
detect
this
com-
pound
in
milk
24
hours
after
administration.
In
dogs,
approximately
half
of
the
rH16a-methylprednisolone
-21-
acetate
given
IM
was
excreted
in
feces,
and
about
a
quarter
of
the
dose
was
present
in
urine
after
42
days!'
Little
is
known
about
the
relative
value
and
the
mech-
anism
of
corticosteroid
activity
in
the
bovine
udder.
The
effectiveness
of
local
corticoid
therapy
in
suppressing
the
inflammatory
response
in
the
udder
has
been
questioned.
The
purpose
of
the
present
study
was
to
define
the
anti-
inflammatory
effects
of
prednisolone
on
the
clinically
nor-
mal
and
the
mastitic
bovine
udder
during
lactation
and
to
examine
systemic
absorption
of
the
drug
and
its
rate
of
excretion
in
milk
and
urine
after
single
intramammary
or
Iv
administration.
Materials
and
Methods
[
3
1116,7,Prednisoione"
lots
with
specific
activities
of
53
and
58
Ci/mmole
were
used.
Authenticity
of
the
labeled
prednisolone
"
Amersham
Corp,
Arlington
Heights,
Ill.
1576
Am
J
Vet
Res,
Vol
45,
No.
8
was
established
by
thin-layer
chromatography
on
silica
gel
by
the
chloroform:ethanol
(80:20)
system.
The
radiolabeled
and
nonradiolabeled
prednisolone
b
was
cochromatographed
and
the
radioactive
prednisolone
was
>
99%
pure.
Cattle
and
experimental
design—Ten
lactating
Holstein
cows
weighing
500
to
700
kg
were
housed,
fed,
and
milked
under
normal
conditions.
Prednisolone
was
investigated
first
in
clin-
ically
normal
udders
(normal
phase)
and
then
after
2
weeks
in
experimentally
infected
udders
of
the
same
cows
(infected
phase).
A
single
dose
of
[
3
H]prednisolone
was
injected
into
each
quarter
of
the
mammary
glands
of
6
healthy
cows;
4
other
healthy
cows
were
given
a
single
Iv
dose
of
[
3
H]prednisolone.
Two
weeks
after
the
normal
phase,
mastitis
was
induced
in
all
cows
by
infection
with
Streptococcus
agalactiae,'
and
another
single
dose
of
[3H]prednisolone
was
administered
as
soon
as
clinical
infection
in
the
udders
was
established.
The
[
3
H]prednisolone
was
used
to
monitor
the
absorption
and
elimination
of
prednisolone
in
normal
and
infected
bovine
udders.
Intramammary
injections
were
given
immediately
after
the
morning
milking
was
completed.
Each
quarter
was
injected
with
a
single
dose
of
[
3
H]prednisolone
(13.5
to
33.8
p.Ci)
and
with
nonradioactive
prednisolone
equivalent
to
10
mg
of
predniso-
lone
in
10
ml
of
peanut
oil
(40
mg/cow).
All
cows
were
milked
with
a
commercial
milker,
and
composite
milk
samples
were
collected
at
0.0,
1.5,
3,
and
6
hours
after
injection
on
the
1st
day
and
twice
daily
(9:00
AM
and
4:00
PM)
thereafter
for
3
days.
Milk
yield
was
measured
by
weight
daily,
and
aliquots
(approx
100
ml)
of
milk
were
examined
for
radioactive
content.
Urine
was
collected
via
indwelling
catheters.'
Total
urine
weight
was
recorded
at
each
milking
(9:00
AM
and
4:00
PM)
and
aliquots
(approx
100
ml)
of
urine
were
taken
for
measurement
of
radioactivity.
Blood
was
drawn
from
a
jugular
vein
at
0
and
0.5
hours,
and
hourly
thereafter
for
7
hours
on
the
1st
day
and
at
each
milking
for
4
days.
Blood
was
centrifuged
and
aliquots
from
the
harvested
serum
were
taken
immediately
for
analysis.
The
remainder
of
the
serum
was
frozen.
Heparinized
blood
sam-
ples
were
collected
at
each
milking
for
total
leukocyte
and
dif-
ferential
counts.
A
single
dose
of
[
3
H]prednisolone,
mixed
with
nonradioactive
prednisolone,
equivalent
to
40
mg
in
3.5
ml
of
60%
ethanol
was
injected
into
the
jugular
vein
of
4
clinically
normal
lactating
cows.
Two
weeks
after
the
normal
phase,
the
udders
of
3
cows
(1
cow
in
the
late
stage
of
lactation
was
released
from
study)
were
experimentally
infected
as
described
earlier,
and
the
cows
were
again
given
a
single
iv
dose
of
[
3
11]prednisolone.
Milk,
urine,
and
blood
were
collected
as
described
previously
with
additional
blood
samples
collected
15
and
45
minutes
after
in-
jection.
Blood
was
drawn
from
the
jugular
vein
contralateral
to
the
side
of
injection.
Dose
preparation
and
injections—The
dose
for
intramammary
infusion
was
prepared
from
labeled
and
unlabeled
portions
of
prednisolone
dissolved
in
95%
ethanol.
Dissolved
[
3
H]prednisolone
(13.5
to
33.8
was
combined
with
nonradioactive
predniso-
lone
and
peanut
oil
to
obtain
a
mixture
containing
10
mg
of
prednisolone
in
10
ml
of
peanut
oil.
Ethanol
was
evaporated
from
the
oil
under
vacuum
(138
kPa)
for
24
hours.
Total
radio-
activity
was
determined
in
aliquots
taken
from
each
injection
dose,
and
each
dose
was
then
transferred
to
a
disposable
syringe
for
intramammary
instillation.
Radioactivity
loss
was
deter-
mined
by
using
ethanol
to
extract
residual
oil
from
used
sy-
ringes
and
vials.
Solution
for
iv
injection
was
prepared
by
mixing
dissolved
[
3
H]prednisolone
(100
to
164
µCi)
and
nonradioactive
prednis-
olone
equivalent
to
40
mg
in
3.5
ml
of
60%
ethanol.
Each
dose
containing
40
mg
of
prednisolone
was
transferred
to
a
5-ml
sy-
b
Sigma
Chemical
Co,
St
Louis,
Mo.
Bardex
Foley
catheter,
20
French
size,
75-m1
balloon,
C
ft
Bard
Inc,
Murray
Hill,
NJ.
ringe.
Radioactivity
lost
after
injection
was
determined
as
pre-
viously
described.
Radioactive
determination—Radioactivity
was
measured
in
a
liquid
scintillation
system.'
The
counting
efficiency
for
3
H
was
46%.
Aliquots
of
500
ill
(each)
of
milk,
serum,
and
urine
were
placed
directly
in
scintillation
counting
vials,
and
10
ml
of
scin-
tillation
fluid'
was
added.
The
contents
were
mixed
and
counted
in
a
conventional
manner.
[
3
H]Prednisolone
was
used
as
the
internal
standard,
and
samples
were
corrected
for
variations
in
counting
efficiencies
(background
and
color
quenching).
Results
were
expressed
as
disintegrations
per
minute
(dpm).
Counting
efficiencies
for
radioactivity
in
urine,
serum,
and
milk
were
62%,
63%,
and
75%,
respectively.
Inoculum—A
culture
of
S
agalactiae,
Cornell
84
strain,'"
was
used
to
induce
mastitis.
An
overnight
broth
culture
of
S
agalactiae
was
swabbed
onto
the
surface
of
large
soybean-casein
agar
plates
and
was
incubated
at
37
C
for
18
hours.
Cells
were
washed
with
sterile
0.85%
saline
solution,
centrifuged,
and
sus-
pended
with
saline
solution
or
Trypticase
soy
broth!
Inoculum
containing
1.0
to
1.5
ml
of
the
S
agalactiae
culture
was
used
to
induce
infection.
Each
quarter
was
injected
with
a
single
inoc-
ulum
immediately
after
the
morning
milking.
At
the
subse-
quent
evening
milking,
all
exposed
udders
were
partially
milked;
thereafter,
normal
milking
procedure
was
followed.
The
exposed
cows
were
observed
and
the
mammary
glands
were
examined
for
local
effects.
Before
each
milking,
foremilk
was
examined
for
physical
characteristics
by
using
the
strip-cup
technique.
Fresh
foremilk
samples
from
each
quarter
(6
and
24
hours
after
inoculation)
were
collected
aseptically,
plated,
and
examined
for
the
pres-
ence
of
mastitis-inducing
pathogens.
When
examination
of
in-
oculated
quarters
exhibited
clinical
signs
of
mastitis,
intramammary
or
iv
administration
of
[
3
H]prednisolone
was
immediately
initiated.
A
single
dose
of
the
[
3
H]prednisolone
was
generally
administered
24
hours
after
inoculation
of
the
udder.
The
minimal
criteria
for
udder
infection
were
colonization
and
recovery
of
S
agalactiae
from
foremilk
samples,
marked
leu-
kocytic
exudation
into
the
milk,
abnormal
secretion,
and
ob-
vious
clinical
signs
of
mastitis
associated
with
edema
and
inflammation.
Bacteriologic
procedures
and
leukocyte
and
somatic
cell
deter-
minations—Foremilk
samples
taken
from
individual
quarters
were
examined
microbiologically.
Microorganisms
were
re-
covered
and
identified
according
to
bacteriologic
procedures
pre-
viously
described!'
Blood
leukocytes
were
counted
electronically
in
a
Coulter
counter,g
and
blood
smears
were
stained
with
Wright's
stain
for
differential
leukocyte
determinations.
So-
matic
cells
in
milk
were
counted
by
the
standard
direct
micro-
scopic
somatic
cell
count
method!'
Milk
smears
were
prepared,
air
dried,
and
stained
with
Levowitz-Weber
or
pyronin
Y-methyl
green
stains.'
Results
Intramammary
injection—Mean
values
of
radioactivity
recovered
in
urine
collected
from
infected
and
normal
cows
accounted
for
25.4
±
6.4%
and
29.6
±
10.5%,
respec-
tively,
of
the
total
dose
administered
(Table
1).
Most
of
the
radioactivity
in
the
urine
was
excreted
within
30
hours.
Recovery
of
radioactivity
in
milk
collected
from
infected
udders
and
normal
udders
within
24
hours
after
prednis-
olone
injection
was
2.0
±
0.9%
and
5.0
±
2.7%,
respec-
tively.
Thereafter,
radioactivity
in
milk
was
negligible.
Spectrometer
Model
L250,
Beckman
Instruments
Inc,
Fullerton,
Calif.
Aquasol-2,
New
England
Nuclear,
Boston,
Mass.
r
Baltimore
Biological
Laboratories,
Microbiology
Systems,
Cockeysville,
Md.
g
Model
FN,
Coulter
Electronics
Inc,
Hialeah,
Fla.
August
1984
1577
a
0-0
NORMAL
0-0
INFECTED
a
x
"
0
-
0
2
3
4
5
6
7
O
TIME
(HOURS)
Fig
1-Mean
serum
radioactivity
(dpm/ml)
in
6
cows
after
single
intramam-
mary
injection
of
[
3
H]prednisolone
before
and
after
induced
infection.
TABLE
1-Elimination
and
recovery
of
[
3
H]prednisolone
from
milk
and
urine
of
cows
after
a
single
intramammary
injection
during
a
4-day
study
I
3
H1Prednisolone
Milk
production
and
recovered
(%)
urine
excreted
(kg)
Milk
Urine
Milk
Urine
9.9
42.2
97.5
99.4
4.6
35.2
89.7
95.1
2.6
28.3
100.2
88.3
2.6
22.6
81.0
71.1
4.4
18.0
167.7
72.8
6.0
18.5
136.0
36.4
5.0
±
2.7
29.6
±
10.5
112.0
±
33.1
77.2
±
23.1
3.4
30.2
29.1
123.5
0.9
21.1
18.7
87.1
1.7
24.7
73.2
70.0
2.8
22.7
55.6 57.8
1.5
18.1
36.3
56.0
1.8
25.4
53.9
63.6
2.0
±
0.9
25.4±
6.4
44.5
±
20.0
76.3
25.7
Radioactivity
in
serum
was
detected
30
minutes
after
in-
tramammary
injection;
prednisolone
radioactivity
peaked
within
2
hours
of
injection
and
gradually
declined
by
9
hours
after
administration.
Activity
values
as
disintegra-
tions
per
minute
per
milliliter
were
averaged
from
6
lac-
tating
cows
in
the
normal
and
infected
phases
(Fig
1).
Milk
production
and
urinary
excretion
were
deter-
mined
for
each
cow
over
4
days
(Table
1).
Total
urinary
output
from
cows
in
the
normal
and
infected
phase
was
similar
(77.2
±
23.1
kg
and
76.3
±
25.7
kg,
respectively).
Radioactivity
in
urine
decreased
to
marginally
detectable
amounts
by
78
hours
after
administration.
Average
total
milk
yield
was
60.27%
(P
>
0.01)
lower
during
the
in-
fected
phase
than
during
the
normal
phase
(44.5
±
20.0
kg
and
112.0
±
33.1
kg,
respectively).
IV
phase-Radioactivity
recovered
in
urine
from
nor-
mal
and
infected
phases
accounted
for
46.0%
and
42.6%
of
the
total
dose,
respectively
(Table
2).
Low
radioactivity
levels
were
detected
in
milk,
with
recovery
averaging
from
0.05%
to
0.13%
of
the
total
dose
administered.
As
ex-
pected,
radioactivity
was
detected
in
both
phases
15
min-
utes
after
iv
administration
of
[
3
1
-
I]prednisolone,
but
was
TABLE
2-Elimination
and
recovery
of
[
3
Fljprednisolone
from
milk
and
urine
of
cows
after
IV
injection
during
a
4-day
study
1
3
H1Prednisolone
Milk
production
and
recovered
(%)
urine
excreted
(kg)
Cow
Milk
Urine
Milk
Urine
NORMAL
PHASE
G
0.06
41.2
41.2
40.1
H
0.14
48.6
46.1
47.8
0.19
41.7
45.9
30.4
J
0.13
52.6
56.0
55.4
Mean
±
SD
0.13
±
0.05
46.0
±
5.5
47.3
±
6.2
43.4
±
10.7
INFECTED
PHASE
G
0.05
38.2
17.9
37.8
H
0.05
29.1
14.4
60.6
J
0.05
60.6
34.4
44.7
Mean
±
SD
0.05
0.0
42.6
±
16.2
22.2
±
10.7
47.7
±
16.7
;
0
2
13-0
NORMAL
0-0
INFECTED
10
,
1
0
'
1
3
TIME
(HOURS)
6
Fig
2-Mean
serum
radioactivity
(dpm/ml)
in
cows
after
single
iv
injection
of
[
3
F11prednisolone
before
and
after
induced
infection.
not
detectable
after
48
hours.
Radioactivity
as
disinte-
grations
per
minute
per
milliliter
in
serum
was
plotted
from
the
data
obtained
during
the
normal
and
infected
phases
(Fig
2).
Radioactivity
in
milk
and
urine
was
detectable
in
both
phases
at
the
1st
milking
(6
hours)
but
diminished
to
trace
levels
by
54
hours
and
was
eliminated
in
urine
by
78
hours.
The
accumulated
urine
production
during
the
4
days
from
normal
and
infected
phases
was
43.4
±
10.7
kg
and
47.7
±
16.7
kg,
respectively
(Table
2).
Milk
pro-
duction
during
the
infected
phase
was
53.06%
(P
>
0.025)
lower
than
that
of
the
normal
phase
(22.2
±
10.7
kg
and
47.3
±
6.2
kg,
respectively).
Clinical
observations-Overall
physical
condition
of
cows
used
in
the
normal
phase
of
study
was
good
and
feed
Cow
NORMAL
PHASE
A
B
C
D
E
F
Mean
±
SD
INFECTED
PHASE
A
B
C
D
E
F
Mean
±
SD
1578
Am
J
Vet
Res,
Vol
45,
No.
8
10
5
0-0
BLOOD
0-0
MILK
10.
tu
LL
3
10
5
TREATED
10'
O
4
5
6
7
8
10
12
2
3
MILKING
10
3
13-13
BLOOD
0-0
MILK
10
6
10.
TREATED
O
MILKING
103
0
2
3
4
5
6
7
8
9
10
11
12
Fig
3—Blood
leukocyte
and
milk
somatic
cell
response
to
prednisolone
after
single
intramammary
injection
in
lactating
cows
in
normal
phase
(values
represent
mean
±
SEM
for
cows
A
through
F
milked
twice
a
day).
Fig
4—Blood
leukocyte
and
milk
somatic
cell
response
to
prednisolone
after
single
iv
injection
in
cows
in
normal
phase
(values
represent
mean
±
SEM
for
cows
G
through
J
milked
twice
a
day).
consumption
was
normal.
Signs
of
gross
abnormalities
or
changes
in
the
physical
character
or
quality
of
milk
were
not
noticed.
All
quarters
were
functional
and
appeared
to
be
free
of
clinical
mastitis.
Gross
clinical
reactions
of
the
cows
were
moderate
after
exposure
to
S
agalactiae.
Twelve
to
24
hours
after
inoc-
ulation,
a
marked
inflammatory
response
associated
with
a
massive
leukocytosis
in
the
milk
was
noticed.
Clinical
signs
in
affected
cows
were
edema
of
the
udder
with
swol-
len,
firm,
and
tender
quarters;
watery,
flaked,
or
thickly
clotted
milk;
and
a
marked
decrease
in
milk
production.
Streptococcus
agalactiae
was
isolated
from
fresh
postex-
posure
milk
samples
and
was
identified
by
standard
pro-
cedures.
In
most
cows,
the
swelling
of
quarters
reached
the
maximum
within
24
to
36
hours
and
subsided
in
sub-
sequent
milkings;
milk
generally
returned
to
normal
ap-
pearance
after
4
days.
Blood
leukocytes
and
somatic
cell
response—In
normal,
noninfected
cows,
the
effect
of
prednisolone
on
blood
leu-
kocytes
after
intramammary
or
iv
administration
was
similar
for
both
groups
of
cows
(Fig
3
and
4).
A
small
transitory
peak
in
blood
leukocytes
after
prednisolone
administration
was
associated
with
changes
in
differen-
tial
leukocyte
profiles
and
a
progressive
increase
in
neu-
trophils.
Regardless
of
the
dose
or
route
of
administration,
the
response
to
prednisolone
was
essentially
the
same.
The
maximum
increase
in
circulating
leukocytes
of
>
3,000
leukocytes/min'
of
blood
occurred
7
hours
after
adminis-
tration,
decreased
within
12
hours,
then
returned
to
base-
line
values
(Fig
3
and
4).
In
milk,
somatic
cell
counts
fluctuated
within
the
es-
tablished
normal
range
for
these
cows
and
revealed
no
changes
in
concentration
after
prednisolone
administra-
tion
(Fig
3).
The
concentration
of
somatic
cells
in
2
of
4
cows
given
iv
injections
remained
at
normal
values
dur-
ing
the
study,
but
indicated
a
considerable
increase
in
cell
count
values
in
2
other
cows
(Fig
4).
This
increase
was
attributed
to
a
transient
inflammation
caused
by
the
presence
of
hemolytic
staphylococci
detected
in
3
quarters
after
the
start
of
the
trial.
The
affected
quarters
of
the
spontaneously
infected
cows
showed
neither
clinical
signs
of
mastitis
nor
gross
changes
in
secretion.
The
leukocyte
response
to
the
infection
(Fig
5
and
6)
was
rapid
in
blood
and
milk.
A
fast
outpouring
of
leu-
kocytes
into
the
milk
of
infected
quarters
was
noticed.
Overall
udder
reactions
24
hours
after
exposure
were
pro-
nounced,
and
the
somatic
cell
counts
in
milk
(16
to
24
million
cells/m1)
were
comparable
for
both
groups
of
cows.
This
high
concentration
of
somatic
cells
in
milk
remained
August
1984
1579
10
6
0-0
BLOOD
0-0
MILK
10
,
10
6
N
U
MB
E
R
O
F
CEL
L
S
10
,
10'
INFECTED
TREATED
10'
2
3
4
5
6
7
8
9
10
11
12
MILKING
0
Fig
5—Blood
leukocyte
and
milk
somatic
cell
response
to
prednisolone
after
single
intramammary
injection
in
cows
in
infected
phase
(values
represent
mean
±
SEM
for
cows
A
through
F
milked
twice
a
day).
10
,
D-13
BLOOD
0--0
MILK
NU
M
B
ER
O
F
CE
LL
S
10
6
10
,
10
6
INFECTED
TREATED
10
3
®
o
2
3
4
5
6
7
10
12
MILKING
Fig
6—Blood
leukocyte
and
milk
somatic
cell
response
to
prednisolone
afte
single
iv
injection
in
cows
in
infected
phase
(values
represent
mean
±
SEM
for
cows
G,
H,
and
J
milked
twice
a
day).
essentially
unchanged
after
prednisolone
treatment
and
persisted
at
somewhat
decreased
amounts
in
most
cows.
A
severe
leukopenia
occurred
within
6
hours
after
in-
fection,
with
an
apparent
massive
exudation
of
leuko-
cytes
into
the
milk
of
the
infected
glands.
As
a
consequence,
there
was
a
precipitous
decrease
in
the
total
leukocyte
count
of
blood
(from
8,000
to
3,000
leukocytes/mm
3
),
fol-
lowed
by
a
return
toward
base
line.
Examination
of
clin-
ical
and
analytical
data
indicated
that
except
for
a
small
transitory
increase
in
circulating
blood
leukocytes,
pred-
nisolone
treatments
at
the
doses
used
neither
affected
the
concentration
of
somatic
cells
in
milk
nor
altered
the
de-
gree
of
inflammation
in
glands
of
infected
cows.
Even
though
all
quarters
of
cows
were
treated
at
once,
the
re-
sponse
obtained
was
not
sufficient
to
cause
decrease
in
swelling
and
overall
clinical
improvement
of
infected
glands.
Discussion
Absorption
of
prednisolone
(based
on
radioactivity)
from
clinically
normal
and
infected
udders
was
rapid,
peaking
in
serum
at
2
hours
after
injection.
Radioactivity
levels
in
milk
were
consistently
below
those
in
serum,
and
ra-
dioactivity
was
not
detected
in
milk
by
3
hours.
Most
of
the
radioactivity
absorbed
from
the
udder
into
the
sys-
temic
circulation
was
excreted
in
the
urine
and
presum-
ably
in
the
feces.
Values
of
radioactivity
recovered
from
urine
of
infected
and
control
cows
accounted
for
25.4%
and
29.6%,
respectively.
In
human
subjects,
90%
of
the
radioactivity
adminis-
tered
as
["C]prednisolone
was
excreted
in
urine
within
48
hours
and
<
2%
was
excreted
in
feces."
After
oral
administration
of
11-116a-methylprednisolone,
21-acetate
in
the
dog,
25%
to
31%
of
the
radioactivity
was
recovered
in
urine
and
44%
to
52%
in
feces.'
In
the
ruminant,
the
major
route
for
prednisolone
excretion
is
presumably
via
the
feces.
The
accumulated
percentages
in
urine
from
an
ovariectomized
cow
after
iv
administration
of
[
H
C]corticosterone
and
["C]cortisol
were
20.2%
and
29.0%,
respectively.'''
In
our
experiments,
the
recovery
of
radio-
activity
in
urine
after
iv
injection
ranged
from
42%
to
46%.
The
radioactivity
content
in
milk
after
intramammary
injection
(<
5%
of
the
total
dose)
and
iv
injection
(<
0.13%
of
the
total
dose)
and
clinical
response
observed
in
this
study
indicate
that
the
concentrations
of
prednisolone
produced
were
generally
below
the
clinically
effective
concentration.
Evidently,
prednisolone
is
quickly
ab-
sorbed
from
the
udder
into
the
systemic
circulation
and
is
quickly
eliminated.
After
iv
injection,
prednisolone
is
also
rapidly
eliminated,
and
little
is
present
in
milk.
1580
Am
J
Vet
Res,
Vol
45,
No.
8