Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 6
some cases of endocarditis and in calves with cardiac
anomalies in which red blood cells are destroyed by
a turbulence in blood flow. Primary anaemia, not
associated with cardiac disease, may also give rise to
signs of exercise intolerance, tachycardia and sometimes
tachypnoea. Other causes of discolouration of
the mucous membranes are discussed under the
General Clinical Examination in Chapter 2.
Capillary refill time
This is a measure of effective cardiac function. Digital
pressure on an area of non-pigmented mucosa of
the lips, dental pad or vulval mucosa causes blanching
of the mucous membranes. Colour should return
quickly – in less than 2 seconds – after pressure is released.
Prolonged capillary refill time of more than 5
seconds is indicative of a poor circulation. It can be
caused by cardiovascular disease or by other abnormalities
such as dehydration.
Apex beat of the heart
The apex beat of the heart, caused by the apex or
point of the heart contacting the chest wall, may be
palpable low down in the chest at the level of the 6th
rib. The apex beat can often be seen and readily palpated
in the new-born calf. Its presence in older animals
may indicate a degree of cardiac enlargement.
Jugular pulse
Some pulsation of the jugular vein associated with
closure of the left atrioventricular (mitral) valve is
normally visible in the lower third of the jugular furrow
on both sides of the body. It is associated with
atrial systole. Compression of the vein in normal animals
should lead to the disappearance of the jugular
pulse as the vein empties. Pulsation extending up to
the angle of the jaw is abnormal and may suggest incompetence
of the tricuspid valve. In such cases compression
of the vein does not result in a loss of the
jugular pulse. The pulsation may be particularly obvious
when the jugular vein is already distended by
circulatory failure. If a normal animal’s head is lowered
– as for example when feeding – pulsation can
often be seen throughout the length of the jugular
veins. This pulsation disappears when the head is
raised and is of no pathological significance. The normal
jugular vein looks full when the head is lowered
and the vein is below the level of the heart. False
jugular pulsation may be observed if pulsation of the
carotid artery beneath the vein is displacing it.
Jugular filling
The filling and emptying of the jugular veins are important
indicators of the efficiency of the cardiovascular
system, especially in terms of venous drainage
(return) and the ability of the heart to pump back
blood from the peripheral and pulmonary circulations.
Distension of the jugular vein can be a sign
of right-sided heart failure and should not be present
in normal animals. Blocking venous return in the
jugular vein by pressing on the vein near the base
of the neck causes rapid distension of the vein in a
normal animal (Fig. 5.21). The distension should disappear
as soon as pressure on the vein is removed.
Release of digital pressure on a distended jugular
vein does not result in it emptying in cases of congestive
heart failure. Distension of the jugular veins may
also be observed in animals in which there is a spaceoccupying
lesion at the thoracic inlet. The large external
abdominal veins (‘milk veins’) which lie below the
level of the heart normally appear full of blood. In dehydrated
animals or those suffering from shock the
jugular veins may appear flat and empty. Pressure on
the lower extremity of the vein may fail to produce
any degree of filling.
CLINICIAN’S CHECKLIST – OBSERVATION
OF THE CARDIOVASCULAR SYSTEM
Patient’s willingness to walk and its exercise tolerance
Presence of rapid breathing – may indicate cardiac or lung
disease
Visible cardiac apex beat
Position of the elbows
Brisket and submandibular oedema
Peripheral pulse – rate, rhythm, strength and character
Colour of mucous membranes
Capillary refill time
Presence of jugular pulse
Jugular filling and jugular vein refill time
Consequences of cardiac failure including renal dysfunction
and diarrhoea
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