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Pulmonary Edema & Congestion

Pulmonary congestion is caused by an increase in the amount of blood in the lungs due to the engorgement of the pulmonary vascularization. Sometime It is followed by pulmonary edema when the intra-vascular fluid escapes into the surrounding parenchyma & alveoli & this will lead to respiratory disturbance & the degree of disturbance depends on the amount of alveolar air
space which is lost.

Etiology:

Primary congestion:
Is the first stage in most cases of pneumonia.
After inhalation of smoke & irritant fumes.
In anaphylactic reactions.
As hypostatic congestion in recumbent animals.

Secondary congestion:

Is usually a manifestation of congestive heart failure affecting the left ventricle when the blood flow through the lungs increased by increased pressure in the pulmonary vessels.

Overexhustion of horses (not by hard work), is characterized by pulmonary congestion which is partly primary & partly secondary due to acute Myocardial asthenia.

Pulmonary edema:

As a result of pulmonary congestion in acute anaphylaxes.
Congestive heart failure.
After inhalation of smoke.
In some toxaemias.
Poisoning with organic phosphorus compounds.
Poisoning by alphanaphthyle thiourea.


The congestion of pulmonary capillaries leads to loss of amount of alveolar air space which leads to reduced vital capacity reduced oxygenation of the blood ,which is also due to reduced blood flow through the pulmonary vs. & this will lead to congestion of lung.

The vital capacity still reduced till appearance of pulmonary edema which is also resulting from the anoxic anoxia caused by reduced oxygenation of the blood & by passage of fluids due to increased hypostatic pressure.

Filling of the alveoli & in severe cases the brorchi, prevents the gaseous exchange.

Clinical findings:
Dyspnea with extended head & mouth breathing.
Exaggerated respiratory movements & increased respiratory rate.
There is marked abdominal & thorasic movements during inspiration & expiration.
Spreading of legs fore limbs wide apart.
Abducted elbow.
Increased pulse rate.
The mucous membrane of the nose is congested.
By auscultation in acute congestion sharp vesicular sound but no (rales) but when edema occurs ,there is rales especially on the ventral parts of the lungs.
There may be emphysema of the dorsal parts of the lungs.
Soft & moist cough.
Serous nasal discharge (in congestion) & frothy may be bloody tinged (in edema).
Death by asphyxial respiratory failure.

Clinical pathology:

Laboratory examination is only of value in differentiating the cases of edema and congestion.
Bacteriological examination of nasal swap.
Complete hematological examination ,presence of more eosinophile than normal.


Necropsy:
In congestion:
Lungs are dark red in colour & excessive quantities of venous blood exude from the surface.
Histologically pulmonary capillaries are engorged with blood.
In edema:
Swelling & loss of elasticity of the lung which pits down on pressure.
Lungs are usually pallor than normal &excessive quantities of serous fluids exude from the cut surface of the lungs.
Histologically there are accumulations of fluids in the alveoli & parenchyma.

Diagnosis:

From symptoms & causative agents.
Response to antibacterial treatment.

Treatment:

Hygienic treatment:
Treat the cause.
Complete rest to the animal at dry & clean environment.
Avoid exercise to the animals.

Medicinal treatment:

Venous suction with removal of 4m 1/ 11Lb.B.W. of blood in severe congestion.
Oxygen therapy in cases of anoxia as well as parentral respiratory expectorants.
In severe cases Atropine sulphate to reduce fluid transudation.
Administration of Ethyle Alcohol 45% + mixture of Silicons & polyhydric alcohol, for the aim of treating the frothy air passages .