Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
1
PATHOLOGY
of
HEART
Congenital Cardiovascular Anomalies:
1- Patent ductus arteriosus:
The
ductus arteriosus
is a short blood vessel
which connects pulmonary artery to aorta in fetal life for diversion of
blood. Normally soon after birth this duct is sealed and remains in the
form of a
ligamentum arteriosum
, in this deformity ductus arteriosus
remains open and blood is continuously shunted between aorta and
pulmonary artery and may led to congestive heart failure, pulmonary
hypertension and cyanosis due to mixing of venous and arterial blood.
2- Atrial septal defect:
There is a developmental defect in atrial septa which
produces continuous overload on the right side of heart leading to
pulmonary hypertension and hypertrophy of right side myocardium.
However, a small defect in septum may persist throughout the life of
animal without causing any clinical illness.
3- Persistent right aortic arch:
Developmental anomaly of aorta in which
the aorta develops from right arch present on right side of trachea and
oesophagus. The ductus arteriosus forms a ring around trachea and
esophagus which causes partial obstruction of trachea and esophagus.
4-Transposition of aorta and pulmonary artery:
When there is a change in
position of aorta and pulmonary artery. The aorta arises from right
ventricle and pulmonary artery from left ventricle. This results in arterial
blood in right and venous blood in left side and has no clinical
significance.
5- Ventricular septal defects:
In fetal life, there is no partition in ventricles
and there is only one chamber which is divided into two right and left
by inter ventricular septum, but when interventricular septum does not
develop completely there is mixing of blood from both chambers. It is
responsible for thickening of myocardium, roughening of endocardium
and cyanosis.
6- Ectopia cordis:
When heart lies outside the thorax under the
subcutaneous tissue of lower cervical region.
7- Pulmonary stenosis:
is characterized by narrowing of lumen of
pulmonary artery at its origin due to fibrous tissue deposition causing jet
effect.
8- Tetralogy of Fallot:
Tetralogy of Fallot includes 4 developmental
defects of cardiovascular system: (1) Ventricular septal defect (2)
Pulmonary stenosis. (3) Hypertrophy of right ventricle (4) Transposition
of aorta.
9-Persist foramen ovale.
10-Multiple hearts.
11- Valvular hematomas.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
2
I- Pathology
of
Pericardium:
1-Hydro pericardium:
is accumulation of clear to light yellow, watery,
serous fluid (e.g. transudate) in the pericardial sac. Hydro pericardium
occurs in those diseases that have generalized edema such as congestive
heart failure, pulmonary hypertension, renal failure, hypoproteinemia
septicemia and anemia.
2-Hemopericardium:
means accumulation of whole blood in the
pericardial sac. Death occurs suddenly from cardiac tamponade. Bleeding
in the pericardial sac can result from spontaneous aterial rapture in dogs,
rapture of the interapericardial aorta in horses or complication of
interacardiac injection.
3-Pericarditis:
Inflammation of pericardium. Pericardium is a serous
membrane. It covered the heart externally and at the same time protect the
heart. Inflammation of the pericardium is due to:
1 - Trauma (foreign body) penetrating from the reticulum.
2- Infection which either hematogenous or by extension from epicardium,
pleura, bronchial or mediastinal lymph nodes or stomach.
Types of the pericarditis
1-Fibrinous pericarditis:
It is an acute inflammatory reaction of
pericardium which characterized by extensive deposition of fibrin on the
pericardial and epicardial surfaces, which become adherent to one
another (
adhesive pericarditis
). It is occurring due to hematogenous
infection e.g. Black leg.
Grossly:
Both visceral and parietal pericardial
surfaces are covered by variable amounts of yellow fibrin deposits which
can result in adherence between the pericardial layers give a gross
appearance torn away when open pericardium called
bread and butter
heart
.
Microscopically:
an eosinophilic layer of fibrin with admixed
neutrophils lies over a congested pericardium.
2- Purulent pericarditis:
Results from pyogenic bacteria localized in the
pericardium, with certain fungi may also cause purulent pericarditis and
associated with purulent pleuritis. Frequent causes include
Streptococcus, Klebsiella, Pasteurella, Staphylococcus, Mycoplasma
and Nocardia spp. Purulent pericarditis rarely resolves and healing
occurs by organization resulting in
adhesive
and
constrictive fibrosing
pericarditis
.
3-Traumatic pericarditis (hard ware diseases):
It is a disease of cattle
resulting from penetrate of the reticular wall and diaphragm by metal
object. Sharp metal object (nails and wire) penetrate the wall of
reticulum and slowly removed encompassed in reactive granulation
tissues usually eliciting only localized peritonitis. The direction that
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
3
foreign object travel is usually anterioventral through the diaphragm and
pleura and into the pericardium and heart. So, pericarditis and
fibrinopurulent pleuritis are developed.
Grossly
the pericardial surface
is notably thickened by white, often rough, shaggy appearing masses of
fibrous connective tissue that enclose an accumulation of white to gray
thick foul smelling of purulent exudate.
4-Gangrenous pericarditis:
Gangrenous pericarditis occurs when
saprophytic bacteria are introduced into pericardial sac when traumatic
pericarditis occurs or when gangrenous pneumonia pleuritis extend to
the pericardium.
4- Neoplasms:
Neoplasms of the pericardium are infrequent.
Fibromas
,
leiomyomas
,
hemangioendotheliomas
may arise in the pericardium, but the
most frequent primary neoplasms are the
mesothelomas
.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
4
II- Pathology
of
Endocardium:
The endocardium is the inner layer of heart.
1- Endocardial mineralization and fibrosis:
Can occur singly or together.
Mineralization occurs from intoxication by calcinogenic plants (Solanum
torvum). Fibrosis with or without mineralization occurs in chronically
dilated hearts and in hearts of debilitated cattle with John's disease.
2- Endocarditis:
inflammation of endocardium, is usually the result of
bacterial or produced by migrating Strongylus vulgaris larvae in horses and
an occasional case of mycotic infection. The lesion on the valves are
termed
valvular endocarditris
although some lesions extend to the wall of
the atrium or ventricle and is termed
mural endocarditis
.
Grossly:
affected
valves have large adhering friable yellow to-gray masses of fibrine termed
vegetations which can largely occlude the valvular orifice, in chronic
lesions the fibrine deposits are organized by fibrous connective tissue to
produce irregular nodular masses of wart like lesions termed
verrucae
.
Microscopically:
the lesion consists of accumulated layers of fibrin and
numerous embedded bacterial colonies underlain by a zone of infiltrated
leukocytes and granulation tissues.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
5
III- Pathology
of
Myocardium:
1- Growth Disturbances:
Hypertrophy of the myocardium represents an
increase in muscle mass due to increase in size of cardiac muscle cells.
Hypertrophy is generally secondary as result of compensatory response to
increased workload. It is usually reversible on removal of the cause.
Primary hypertrophy occurs due to valvular insufficiency and stenosis,
septal defects and pulmonary diseases.
2- Infiltration:
Fatty infiltration occur due to increased numbers of
lipocytes interposed between myocardial fibers. The lesion is associated
with obesity and appears as abundant epicardial and myocardial deposits
of adipose tissue.
3- Degeneration:
a- Fatty degeneration: (Fatly change):
is the accumulation of abundant
lipid droplets in the sarcoplasm of myocytes. This lesion occurs with
anemia, toxemia, copper deficiency.
Grossly
the myocardium is pale
flabby.
Microscopically
affected myocytes have numerous vacuoles of
fat droplet that appear empty in section.
b- Hydropic degeneration:
it mainly associated with administration of
antineoplastic drug and chronic passive congestion with ascites.
c- Lipofuscinosis:
(
brown atrophy
): of the myocardium occurs in aged
animals and in animals with sever cachexia.
Grossly
the affected hearts
appear brown in color,
macroscopically
have cluster of yellow to brown
granules at the nuclear poles of myocytes.
5- Myocardial necrosis
can result from a number of causes including
nutritional deficiencies
,
chemical
and
plant toxins
,
ischemia
,
metabolic
disorders
,
heritable diseases
and
physical injuries
.
6- Myocardial mineralization
: is a prominent feature in several diseases
such as
hereditary calcinosis in mice
,
vitamin E and Selenium deficiency
in sheep and cattle
,
vitamin D toxicosis in several species
,
calcinogenic
plant toxicosis in cattle
(
Manchester wasting disease
)
7-Circulatory Disturbances:
includes hemorrhage, thrombosis, infarction.
Hemorrhage occur in selenium and vitamin E deficiency. Thrombus in
coronary artery cause infarction, as in case of hyperthyroidism which cause
thrombosis which cause later infarction.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
6
8- Myocarditis:
Inflammation of myocardial muscle. Myocarditis
generally result by infection spread hemategenously to the myocardium
and occurs in various systemic diseases such
FMD
,
ND
,
listeriosis, black
leg
,
tuberculosis
,
necrobacillosis
. myocarditis types depend on causative
agent which can classify as:
1- Suppurative Myocarditis.
2- Necrotizing Myocarditis.
3- Hemorrhagic Myocarditis.
4- Lymphocytic Myocarditis.
5- Eosinophilic Myocarditis.
8- Neoplasm:
Various primary and secondary neoplasm develops either in
or near the heart. The primary neoplasms include
rhabdomyoma
,
rhabdomyosarcoma
schwannoma
and
hemangiosarcoma
.
While
secondary neoplasms included
Hemangiosarcoma
,
lymphosarcoma
.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
7
PATHOLOGY
of
VASCULAR SYSTEM
I- Pathology
of
Arterial diseases:
1- Aneurysm and raptures:
An Aneurysm is a localized dilation or out
pouching of a thinned and weakened portion of a vessel. Usually in large
elastic arteries but the lesion can also occur in veins. Known causes include
copper deficiency in Pigs
,
infection with Spirocerca lupi in dogs
or
Strongylus vulgaris in horses
,
sequela of severe trauma
or
occur
spontaneously
.
2- Arterial hypertrophy:
is a response to sustained increases in pressure or
volume loads. Affected vessels are generally muscular arteries. It may be
physiological hypertrophy
as in
uterine arteries during pregnancy
, or
pathological hypertrophy
associated with infection by several parasites
including
Lung worm of cats
,
Toxocara spp
and
Dirofilaria mitis
.
3- Degeneration and Necrosis:
a- Arteriosclerosis:
is characterized by
intimal mucopolysaccharides
deposit and fibrosis of large elastic arteries
. It is an age-related disease
that occurs frequently in many animal species but rarely causes clinical
signs, the disease develops as a chronic degenerative and proliferative
response in the arterial wall and results in loss of elasticity (
hardening
of the arteries
) and luminal narrowing. The abdominal aorta is most
frequently affected.
Grossly:
the lesions are seen as slightly raised firm,
white plaques in artery walls.
Microscopically:
initially the intima is
thickened by accumulation of mucopolysaccharides and later by the
proliferation of smooth muscle cells in the tunica media with fibrous
tissue infiltration into intima splitting and fragmentation of the internal
elastic lamina are common.
b- Atherosclerosis:
A vascular disease of greatest importance in human
being. It is characterized by
intimal and medial lipid deposits in elastic
and muscular arteries
. The principle alteration is accumulation of lipid
deposits in vessel wall which result in luminal narrowing. Rabbit,
chicken, cow, goat and rat are resistant to natural occurrence.
Grossly:
Arteries of heart, mesentery, kidneys are prominently thickened firm and
yellow to white.
Microscopically
, lipid globules accumulated in the
cytoplasm of smooth muscle cells and macrophages, often termed
foam
cell
in the media and intima.
c- Arterial medial calcifications:
are frequent lesion characterized by
calcium salt deposit in and muscular arteries
. The causes of arterial
medial calcification include
calcinogenic plant toxicosis
,
vitmin D
toxicosis
,
renal insufficiency
and se
ver debilitation as seen in John's
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
8
disease
.
Grossly:
Affected arteries such as aorta have a unique gross
appearance, they appear as a solid, dense pipe like structures with raised
white solid intimal plagues.
Microscopically:
lesions in
elastic arteries,
prominent basophilic granular mineral deposits are present on elastic
fibers of media. In
muscular arteries,
a complete ring of mineralization
in the tunica media.
4-Inflammation of arteries (Arteritis):
occurs as a feature of many
infections and immune mediated diseases. Often, all types of vessels are
affected rather than only arteries, and then
vasculitis
or
angiitis
is term
applied to the lesions. It is characterized by inflammatory reaction in the
arterial wall, the nature of inflammation varying with specific causes,
arteritis either
primarily
when causative agent affect artery or
secondarily
,
as a part of any inflammatory disease of other tissues.
Causes:
1-
Metazoan parasites
,
Strongylus vulgaris
in horse,
Spirocerca lupi
and
Dirofilaria immitis
in dogs.
2-
Viral infection
,
Equine viral arteritis
,
Blue tongue
,
Hog cholera
.
3-
Bacterial infection
,
Haemophilus
spp.
4-
Mycotic disease
,
Aspergillus fumigatus
.
Lesions:
-Grossly:
The affected artery in thickened and fluctuated touch with
surrounded hyperemic area.
-Macroscopically:
In inflamed vessels, leukocytes will be present within
and surrounding the wall, the damage to the blood vessel wall be evident
as fibrin deposits with necrotic endothelia and smooth muscle cells. These
vascular alterations are accompanied by thrombosis which result in
ischemic injury or infarction in the circulatory field.
5-Neoplastic
Diseases:
Neoplasms arising from vascular endothelium cell
in many different organs includes:
hemangioma
,
hemangiosarcoma
(origin
endothelial cells)
hemangiopericytoma
a more common in blood vessels of
skin in dog.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
9
II- Pathology
of
Venous Diseases:
1- Congenital anomalies:
A venous dilation at weakened part, which is:
- Localized involvement: at area of vascular walls, it is termed
varicosity
.
- Generalized dilatation: occur in superficial veins of legs, it is rather
uncommon in animals
Phlebectasia
.
2- Phlebitis:
Inflammation of veins it may arise from:
1- Systemic infections.
2- local extension of infection.
3- faulty interavenous injection procedure.
3- Omphalophlebitis: (navel ill):
Inflammation of umbilical veins, occur in
neonatal when their umbilical cord infected by pyogenic bacteria
immediately following parturition which is often complicated by
thrombosis.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
10
III- Pathology
of
Lymph Vessel:
1- Congenital Anomalies - Hereditary lymph edema:
Affected animals
have prominent subcutaneous edema that, in calves often causes sever
swelling of the tips of the ears. Interference with lymph drainage results
from defective development of the lymph vessels that are a plastic or
hypoplastic.
2- Lymphangiectasia:
is a dilatation of lymph vessels, result from
obstruction by invading masses of malignant neoplasms.
3- Rapture:
rapture of the thoracic duct is frequently occurred as a result
of trauma cause chylothorax in dogs and cats.
4- Lymphangitis:
Inflammation of lymphatic vessels it is a feature of many
diseases (TB, Glanders, Actinobacillosis), the effected vessels are often
located in the distal limbs which appear thick, cord-like structures with
lymph edema also can be present. its types:
1-
Nodular suppurative lymphangitis
, occur in front limb lymph vessels in
glanders disease.
2-
Granulomatous lymphangitis
, occur in mesenteric lymph vessels in
John's disease.
5- Neoplastic Diseases:
Lymphangioma
is only known primary neoplasms
of the lymphatics.
Systemic Pathology /
Cardiovascular System
/
Dr. Saevan Saad Al-Mahmood
-
11
-
Cardiac Failure
Cardiac failure is the inability of heart to maintain adequate blood
supply leading to death. It can be divided into types:
1- Acute cardiac failure:
sudden failure of contraction of heart leading to
death within minutes.
2- Chronic Cardiac Failure:
Chronic cardiac failure is the inability of heart
to maintain balance between its output and venous return of blood. It can
be divided into left and right sided heart failure.
a- Left Sided Heart Failure:
caused by myocardial damage and
characterized by congestion and edema in lungs with hypertrophy of
alveolar lining cells.
b- Right Sided Heart Failure:
caused by a disease of lungs or
pulmonary vasculature and mostly occurs after a left sided heart
failure.
3- High Altitude Heart failure:
Brisket disease is a condition of slow
cardiac failure, mostly seen at 2.5 kilometers above sea level, this occur
due to low oxygen level, or decrease in air pressure.