Pulsed Wave-Doppler Ultrasonographic Evaluation of the Mammary Blood Flow in the Ewe

Abstract

Piccione G., A. Arcigli, A. Assenza, M. Percipalle, G. Caola: Pulsed Wave-Doppler Ultrasonographic Evaluation of the Mammary Blood Flow in the Ewe. Acta Vet. Brno 2004, 73: 23-27. The authors investigated mammary blood flow by means of a pulsed wave-Doppler ultrasonographic technique in ewes during different production phases. Three groups (Ga, Gb, and Gc, five animals in each) of Comisana sheep were used in the experiment. Ga sheep were milked twice a day by means of a milking machine; Gb sheep nursed their lambs, and group Gc was made up of dry sheep. Recordings of systolic and diastolic pressure of the left and right lateral mammary veins (SSLMV and DSLMV) and arteries (SSLMA and DSLMA) were carried out by means of a Pulse Doppler system. Recordings for Ga were taken before and after milking in the morning and in the afternoon. In Gb and Gc sheep, recordings were taken only in the morning and in the afternoon. Statistical analysis was carried out of the mean values of the recordings taken as mentioned above and the Student'st-test for paired data was used. A statistically significant difference was found in Ga recordings carried out before and after morning (0.05 < P < 0.001) and afternoon (0.05 < P < 0.01) milking. Ga morning mean flow speeds were between 7.00 ± 1.87 and 12.20 ± 2.28 cm/sec for SSLMV; 19.70 ± 3.51 and 32.40 ± 4.77 cm/sec for SSLMA; 2.40 ± 0.55

Full text

Pulsed Wave-Doppler Ultrasonographic Evaluation of the Mammary
Blood Flow in the Ewe
G. PICCIONE, A. ARCIGLI, A. ASSENZA, M. PERCIPALLE, G. CAOLA
Department of Morphology, Biochemistry, Physiology and Animal Productions – Section of Veterinary
Physiology – Faculty of Veterinary Medicine – University of Messina – Polo
Universitario dell’Annunziata – 98168 Messina
Received November 27, 2002
Accepted February 11, 2004
Abstract
Piccione G., A. Arcigli, A. Assenza, M. Percipalle, G. Caola: Pulsed Wave-Doppler
Ultrasonographic Evaluation of the Mammary Blood Flow in the Ewe. Acta Vet. Brno 2004, 73:
23-27.
The authors investigated mammary blood flow by means of a pulsed wave-Doppler
ultrasonographic technique in ewes during different production phases. Three groups (Ga, Gb, and
Gc, five animals in each) of Comisana sheep were used in the experiment. Ga sheep were milked
twice a day by means of a milking machine; Gb sheep nursed their lambs, and group Gc was made
up of dry sheep. Recordings of systolic and diastolic pressure of the left and right lateral mammary
veins (SSLMV and DSLMV) and arteries (SSLMA and DSLMA) were carried out by means of
a Pulse Doppler system. Recordings for Ga were taken before and after milking in the morning and
in the afternoon. In Gb and Gc sheep, recordings were taken only in the morning and in the
afternoon. Statistical analysis was carried out of the mean values of the recordings taken as
mentioned above and the Student’s t-test for paired data was used. A statistically significant
difference was found in Ga recordings carried out before and after morning (0.05 < P < 0.001) and
afternoon (0.05 < P < 0.01) milking. Ga morning mean flow speeds were between 7.00 ± 1.87 and
12.20 ± 2.28 cm/sec for SSLMV; 19.70 ± 3.51 and 32.40 ± 4.77 cm/sec for SSLMA; 2.40 ± 0.55
and 5.60 ± 0.55 cm/sec for SDLMV, and 4.00 ± 1.00 and 8.20 ± 3.83 cm/sec for SDLMA. Ga
afternoon mean flow speeds were between 8.80 ± 1.30 and 12.60 ± 2.30 cm/sec for SSLMV; 20.20
± 2.86 and 29.20 ± 5.76 cm/sec for SSLMA; 2.40 ± 0.55 and 6.40 ± 2.30 cm/sec for SDLMV, and
3.20 ± 0.84 and 7.00 ± 2.83 cm/sec for SDLMA. No significant differences were found between
morning and afternoon recordings in Gb and Gc sheep or between systolic and diastolic speeds of
right and left mammary veins and arteries in the 3 groups.
Our results showed that mechanical milking may influence the vascular mammary flow. It may
lower the intramammary pressure, increase blood flow and activate mammary metabolism.
Furthermore ultrasonographic techniques could be useful for functional assessment of mammary
gland activity.
Pulsed doppler, systolic speed, diastolic speed, lactation, dry period, Ovis aries
It is known that changes in the functional and physiological state of the mammary gland
are related to mammary blood flow. Nutrient uptake and metabolic by-product removal in
the gland occur by means of blood flow and arterial-venous difference. Therefore accurate
measurements of mammary blood flow are useful for the assessment of nutrient and
hormone uptake (Kensinger et al. 1983).
Several investigations have been carried out in ruminants in order to study vascular flows
and to provide information about the functional condition of the mammary gland during
lactation. Four different techniques for the assessment of mammary blood flow were
compared. Continuous thermo-dilution and electromagnetic induction techniques were very
accurate, but harmful and difficult (Linzell 1970; Reynoldset al.1968) while antipyrine
absorption and nitrous oxide diffusion are not extremely reliable.
ACTA VET. BRNO 2004, 73: 23–27
Address for correspondence:
Prof. Giuseppe Piccione
Department of Morphology, Biochemistry, Physiology and Animal Production
Faculty of Veterinary Medicine – Polo Universitario dell’Annunziata
98168 Messina - Italy
Phone: +39 090 357 221
Fax: +39 090 356 195
E-mail: Giuseppe. Piccione@unime.it
http://www.vfu.cz/acta-vet/actavet.htm

Doppler ultrasonographic method, as
described by Drost (1978), is useful for
mammary blood flow recordings. It is
based on ultrasound transit and its probe
does not have to be surgically applied to
the examined blood vessel as in other
Doppler techiques (Gorewit et al. 1989).
Today Doppler ultrasonographic
method supplies useful haemodynamic
data. It plays a leading role in vascular
function investigations because it is
a reliable, easy to run and harmless
method.
Circulatory phenomena are complex
organic functions that may be influenced
by several factors such as blood viscosity,
vascular walls elasticity, rhythm of the
cardiac pump discontinuous activity,
various resistance to blood flow in tissues,
and spontaneous or induced vasomotor
responses (Dauzat 1988).
On the basis of this knowledge we
investigated mammary blood flow by
means of a pulsed wave-Doppler
ultrasonographic technique.
Materials and Methods
Ten Comisana sheep (2-year-old, 45th day of
lactation, mean milk production: 500 ml/day) and
five Comisana sheep (3-year-old, dry subjects) were
used for our study. All animals were clinically
healthy and well fed.
Animals were stabled in paddocks of Istituto
Zootecnico Sperimentale della Sicilia’s facilities and
were divided into three groups (Ga, Gb, and Gc; 5
subjects each). Subjects in Ga were in their first
lactation, and were fed twice a day a unifeed diet (400
g/subject/day of pellet feed 18% of proteins, 1.8-2.0
kg/subject/day of hay and water ad libitum). Animals
were milked twice a day (at 07.00 h and at 17.00 h)
by means of a milking machine (Laval Alpha- De
Laval, UK). Subjects in Gb were in their first
lactation, nursed their lambs, and were fed twice
a day a unifeed diet (400 g/subject/day of pellet feed
16% of proteins, 1.8-2.0 kg/subject/day of hay and
water ad libitum). Subjects in Gc delivered for the
first time and at the time of our study were dry; these
subjects were fed a unifeed diet (200 g/subject/day of
pellet feed 15% of protein, 1 kg/subject/day of hay
and water ad libitum).
In all subjects recordings of speeds of systolic and
diastolic flow of right and left lateral mammary veins
and arteries (Barone 1983) were carried out by
means of a Pulsed Doppler System (PW-mode, 8
MHz probe, 50% gain, 7.5 power and 10 mm depth).
The probe was placed on the blood vessel to clearly
24
Experimental Conditions
Parameters Ga Gb Gc
(cm/sec) Morning Afternoon
B.M. A.M. B.M. A.M. Morning Afternoon Morning Afternoon
Right side
Mammary vein Syst. speed 7.00±1.87 11.00±4.24a12.60±2.30 9.20±1.64b10.40±1.34 11.20±3.35 6.40±1.56 5.80±2.50
Diast. speed 2.40±0.55 5.60±0.55c6.40±2.30 2.40±0.55b2.60±0.55 3.40±1.14 1.80±0.55 1.40±0.86
Mammary artery Syst. speed 28.00±2.00 32.40±4.77a26.20±5.07 20.20±2.86a23.20±2.17 21.20±1.92 6.90±1.55 6.80±1.79
Diast. speed 5.40±0.89 7.20±1.64a6.00±1.73 3.80±1.10a6.00±1.73 6.00±1.58 1.50±1.00 1.57±0.45
Left side
Mammary vein Syst. speed 8.40±2.51 12.20±2.28a11.20±2.77 8.80±1.30a12.20±2.95 13.00±3.16 7.00±1.56 6.50±0.89
Diast. speed 2.40±0.55 4.40±1.14a3.20±0.84 2.40±0.55a4.00±1.22 4.40±0.89 2.00±0.55 1.60±0.89
Mammary artery Syst. speed 19.60±3.51 30.60±7.67b29.20±5.76 21.40±2.07a22.00±3.94 19.40±3.36 8.20±1.40 7.40±0.68
Diast. speed 4.00±1.00 8.20±3.83a7.00±2.83 3.20±0.84b4.40±1.34 5.00±1.22 1.90±0.60 1.70±0.75
Table 1: Mean values (with standard deviations) of left and right mammary artery and vein systolic and diastolic speeds in Ga (sheep mechanically milked twice a day),
Gb (sheep with suckling lambs) and Gc (dry sheep)
B.M. = Before milking; A.M. = After milking
A.M. vs B.M.: a= P < 0.05; b= P < 0.01; c= P < 0.001

visualize blood flow. Recordings for Ga were taken before and after milking in the morning and in the afternoon.
Gb and Gc recordings were taken twice a day (once in the morning and once in the afternoon). Recordings were
carried out with animal in lateral (right and left) recumbency. Seven days prior to our investigation, all ewes
underwent an adaptation period consisting of lying animals in lateral recumbency and handled (including recording
of heart rate in order to evaluate stress) in a Doppler equipment. During our recordings of vascular flow speeds,
heart rate in the sheep was between 66 and 129 beats/min (physiological values for this species) (Hec ke r 1983).
In order to reduce as much as possible the examination bias, handlings during the adaptation periods and recordings
were done by the same well-experienced operator. Since intragroup variance showed no statistical difference,
statistical analysis was carried out on mean values of the recorded parameters. In order to obtain a statistical
significance the following recordings taken on right and left mammary veins and arteries were compared: for Ga,
recordings taken in the morning and in the afternoon, before and after the milking; in Gb and Gc, recordings taken
in the morning and in the afternoon. Student’s t-test for paired data was applied to these values.
Results
Table 1 shows mean values of the mammary vascular index in all groups, expressed in
cm/sec with standard deviation (SD) and statistical significance obtained comparing
recordings taken during the different moments in left and right recumbency in Ga, Gb,
and Gc.
Statistically significant differences were found in Ga recordings carried out before and
after morning (0.05 < P< 0.001) and afternoon (0.05 < P< 0.01) milkings. No significant
differences were found between morning and afternoon recordings in Gb and Gc or
between systolic and diastolic speeds of right and left mammary veins and arteries in the
3 groups.
Discussion
Analysis of the results showed changes in systolic and diastolic mammary lateral veins
and arteries speed between morning and afternoon milking in Ga. In particular, the
significant increase of the flow may be due to a decrease in intramammary pressure. Ga
morning mean flow speeds were between 7.00 ± 1.87 and 12.20 ± 2.28 cm/sec for SSLMV;
19.60 ± 3.51 and 32.40 ± 4.77 cm/sec for SSLMA; 2.40 ± 0.55 and 5.60 ± 0.55 cm/sec for
SDLMV, and 4.00 ± 1.00 and 8.20 ± 3.83 cm/sec for SDLMA. Ga afternoon mean flow
speeds were between 8.80 ± 1.30 and 12.60 ± 2.30 cm/sec for SSLMV; 20.20 ± 2.86 and
29.20 ± 5.76 cm/sec for SSLMA; 2.40 ± 0.55 and 6.40 ± 2.30 cm/sec for SDLMV, and 3.20
± 0.84 and 7.00 ± 2.83 cm/sec for SDLMA. The inverse linear relationship among the
mammary blood flow and the intramammary pressure is well-known (Pearl et al. 1973).
Furthermore, intramammary pressure decreases occurring at the beginning of lactation may
be responsible for the postpartum mammary blood flow increase (Reynolds 1969).
Pressure modifications within a non-expansible organ may be a leading factor in the local
blood flow control in that particular organ. This theory gained growing interest as it was
demonstrated that tissue pressure plays an important role in determining vascular resistance
in the kidney.
By developing a model that illustrates the effects of transmural pressure on blood flow, it
was possible to demonstrate that if an extravascular pressure value is in-between arterial and
venous pressure values, flow will be proportional to the difference between the arterial and
extravascular pressure (Haddy et al. 1965; Hinshaw et al. 1959). This supports the
evidence for a linear relationship between intramammary pressure and mammary blood
flow.
Results obtained in sheep with suckling lambs (Gb) confirm the influence of
intramammary pressure on mammary blood flow. Interestingly, this group reveals no
differences between morning and afternoon mammary blood flow values as a consequence
of constant udder stimulation by the suckling lamb. Gb morning mean flow speeds were
between 10.40 ± 1.34 and 12.20 ± 2.95 cm/sec for SSLMV; 22.00 ± 3.94 and 23.20 ± 2.17
25

cm/sec for SSLMA; 2.60 ± 0.55 and 4.00 ± 1.22 cm/sec for SDLMV, and 4.40 ± 1.34 and
6.00 ± 1.73 cm/sec for SDLMA. Gb afternoon mean flow speeds were between 11.20 ± 3.35
and 13.00 ± 3.16 cm/sec for SSLMV; 19.40 ± 3.36 and 21.20 ± 1.92 cm/sec for SSLMA;
3.40 ± 1.14 and 4.40 ± 0.89 cm/sec for SDLMV, and 5.00 ± 1.22 and 6.00 ± 1.58 cm/sec for
SDLMA.
In mammary physiology, individual differences in venous anastomosis and between
lactating and dry animals must always be considered. Except for the lactation period, sheep
and goat udders are drained only by external pudenda veins and the blood carried by the
abdominal subcutaneous veins. When mammary glands are active their valves are
ineffective and bloodstream flows toward the chest; consequently udders are drained by both
the external pudenda and the subcutaneous abdominal veins (Barone 1983).
In Gc, very low circulatory speeds have been recorded (2.00 ± 0.55 and 8.20 ± 1.40 cm/sec
for lateral mammary artery diastolic and systolic speed, and 1.00 ± 0.45 and 7.79 ± 1.32
cm/sec for lateral mammary vein diastolic and systolic speed). In dry animals, the lower and
steadier mammary blood flow values recorded can be explained in terms of gland inactivity
and of the physiological peculiarity mentioned above; this agrees with earlier research
carried out on dry Holstein cows (Kensinger et al. 1983).
The analysis of the specific literature so far indicates that this approach has not been used
in sheep as yet. Therefore, the discussion of our results cannot profit from a comparison with
other studies in this species.
It can be stated that mammary flow velocity values recorded in right and left mammary
arteries and veins in the sheep represent preliminary values. Further investigations are
needed before using this technique also from a clinical point of view.
Our results showed that mechanical milking may influence vascular mammary flow. It
may lower intramammary pressure, increase blood flow and activate mammary metabolism.
Furthermore ultrasonographic techniques could be useful for functional assessment of
mammary gland activity as already anticipated for the cow (Thivierge et al. 2000).
Pulzní doppler-ultrasonografické vy‰etfiení rychlosti proudûní krve
v mléãné Ïláze u ovce
Autofii sledovali prÛtok krve v mléãné Ïláze pomocí pulzní doppler-ultrasonografické
techniky u bahnic bûhem rÛzn˘ch produkãních fází. V experimentu byly pouÏity 3 skupiny
ovcí plemene Comisana (Ga, Gb a Gc, po 5 zvífiatech). Ga ovce byly dojeny dvakrát dennû
pomocní dojicího stroje, Gb ovce mûli pod sebou jehÀata, a skupina Gc byla sestavena ze
zasu‰en˘ch ovcí. Záznamy systolického a diastolického tlaku levé a pravé laterální Ïíly
mléãné Ïlázy (SSLMV a DSLMV) a arterií (SSLMA a DSLMA) byly provedeny pomocí
pulzního doppler systému. Mûfiení u Ga bylo provedeno pfied a po dojení ráno a odpoledne.
U Gb a Gc ovcí byla mûfiení provádûna pouze jednou ráno a jednou odpoledne. Získané
v˘sledky byly statisticky vyhodnoceny a pro párová data byl pouÏit StudentÛv t-test.
Statisticky v˘znamné rozdíly byly zji‰tûny v mûfieních skupiny Ga proveden˘ch pfied a po
ranním (0.05 < P< 0.001) a odpoledním (0.05 < P< 0.01) dojení. PrÛmûrn˘ ranní prÛtok
skupiny Ga se pohyboval mezi 7.00 ±1.87 a 12.20 ±2.28 cm/s pro SSLMV; 19.70 ±3.51
a 32.40 ±4.77 cm/s pro SSLMA; 2.40 ±0.55 a 5.60 ±0.55 cm/s pro SDLMV, a 4.00 ±1.00
a 8.20±3.83 cm/s pro SDLMA. PrÛmûrn˘ odpolední prÛtok této skupiny se pohyboval mezi
8.80 ±1.30 a 12.60 ±2.30 cm/spro SSLMV; 20.20 ±2.86 a 29.20 ±5.76 cm/s pro SSLMA;
2.40 ±0.55 a 6.40 ±2.30 cm/s pro SDLMV, a 3.20 ±0.84 a 7.00 ±2.83 cm/s pro SDLMA.
Îádné signifikantní rozdíly nebyly zji‰tûny mezi ranními a odpoledními mûfieními uGb a Gc
ovcí ãi mezi systolick˘m a diastolick˘m prÛtokem pravé a levé Ïíly a tepny mléãné Ïlázy.
Na‰e v˘sledky ukazují, Ïe mechanické dojení mÛÏe ovlivÀovat prÛtok krve mléãnou
Ïlázou, sniÏovat intramammární tlak, zvy‰ovat prÛtok krve a aktivovat metabolismus
26

mléãné Ïlázy. Navíc ultrasonografická technika by mohla b˘t uÏiteãná pro funkãní stanovení
aktivity mléãné Ïlázy.
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