5 Diseases of the lung - Pneumonia

1. Diseases of the lung :
Pneumonia
Dr. Karima Al-Salihi

2. Definition:
It is an inflammation of the lung tissue
and usually accompanied by
inflammation of the bronchioles and
pleura. It is manifested clinically by
an increase in respiratory rate,
cough, abnormal breath sounds on
auscultation and in most bacterial
pneumonia, by evidence of toxaemia.

3. Aetiology:
(1)Most o f the pneumonias in animals are
bronchogenic in origin (airogenic) but
some originated by the haematogenous and
lymphatic route or by extension from
neighbouring inflamed tissue.
(2) Non infectious cases such as:
1) Exposure to cold and air currents with severe fatigue.
2) Bad ventilation stables.
3) Inhalation o f irritant gases and vapour.
4) Vitamin C and or vitamin A deficiency and a defect of
immune protective mechanism.

4. 5) Over excretion as traveling for long
distance.
6) Drenching pneumonia.
7) Too old and too young animals are
more susceptible specially the debilitated
ones.
(3) Pneumonia may be caused by
viruses, bacteria (or a combination of
both), fungi and parasites.
(4) Pneumonia are grouped here
according to species:

5. (1)Cattle:
1) Pneumonic pasteurellosis (shipping fever):
Pasteurella haemolytica, Pasteurella multocida.
2) Enzootic pneumonia of calves: parainfluenza-3,
adenovirus 1,2 and 3, rhinovirus, bovine
respiratory syncytial virus, bovine herps virus
(IBR), Actinomyces, Corynbacterium pyogens and
streptococcus sp.
3) Contagious bovine pleuropneumonia
(Mycoplasma mycoides).
4) Lung worm pneumonia (Dictyocaulus
viviparus).
5) Sporadically in tuberculosis caused by
Mycobacterium bovis.

7. (2) Horses:
1) pleuropneumonia in mature
horses, due to aerobic and
anaerobic bacteria.
2) Newborn foals: Streptococcus
sp., E.coli and Actinobacillus
equi.
3) Older foals: Corynebacterium
equi, Equine herpes virus and
Equine influenza virus.
4) Dictycaulus arnfeldi and
Parascaris equorum.
5) Galnders and epizootic
lymphangitis.

8. (3) Sheep:
1) Pneumonic pasteurellosis (Pasteurella sp.)
2) Newborn lambs (uncommonly
Streptococcus zooepidemicus, Salmonella
abortus-ovis).
3) Severe pneumonia due to Mycoplasma sp.
in lambs.
4) Symptomless pneumonias without
secondary infection adenovirus, respiratory
syncytial virus, reovirus and mycoplasma sp.
5) Corynebacterium pseudotuberculosis.
6) Lung worm (Dictyocaulus filaria).

9. Pathogenesis:
ØThe process by which pneumonia develops varies
with:
1) Causative agent and
its virulence
2) Portal by which it
is introduced into the
lung

10. a primary bronchiolitis which spreads to involve
surrounding pulmonary parenchyma
Bacteria are introduced largely by
way of the respiratory passages
The reaction of the lung tissue may be in
the form of:
1) An acute fibrinous process as in pasteurellosis.
2) Necrotizing lesions as in infection with Fusobacterium necrophorum.
3) As a more chronic caseous or granulomatous lesion in mycobacterial or
mycotic infections.

11. 4) Spread o f the lesion through the lung
occurs by:
1- Extension and passage of infective
material along bronchioles and lymphatics.
2- The spread along air passages is facilitated
by the normal movements of the bronchiolar
epithelium and by coughing.
NB: Hematogenous infection by bacteria results
in a varying number o f septic foci which may
enlarge to form lung abscesses. Pneumonia
occurs when these abscesses rupture into air
passages and spread as a secondary
bronchopneumonia.

12. (3) Viral infection are also introduced chiefly
by inhalation and cause a primary bronchiolitis
but it is characterized by absence of acute
inflammatory' reaction and toxaemia.
1) In viral infection, spread to alveoli causes
enlargement and proliferation of the alveolar
epithelium and the development o f alveolar
edema.
2) Viral pneumonia is characterized by
development of interstitial pneumonia results in
consolidation of pulmonary parenchyma without
involvement o f the bronchi and on auscultation
loud bronchial sound is heard.

14. NB: The pathophysiology of all types of
pneumonia is based upon the interference
with gaseous exchanges between the
alveolar air and the blood, because o f the
obliteration of the alveolar air space and
obstruction of air passage.
The reduction o f oxygenation o f the blood
is due to the failure o f a part of circulating
blood to come in contact with oxygen so
cyanosis is most likely to develop and this
lead to anoxic anoxia and hypercapnia.

15. •Clinical signs:
Signs depend on the stage o f the disease and
secondary bacterial pneumonia.
(1) In early stages of viral pneumonia.
1) Mild depression and anorexia.
2) Marked elevation in body temperature.
3) Serous to mucopurulent lacrimal and nasal
discharges.
4) Cough and elevated respiratory rates in the early
stage cough is dry, painful and harsh, but in late
stage cough is moist and painless.
5) On auscultation of the lungs there may be an
increase in breath sounds.

16. (2) In severe inflammation and toxemia (Bacterial
pneumonia):
1) Fever of 40°C.
2) Deep laboured inspiration with extension of the head.
3) Dyspnoea in both respiratory and expiratory.
4) Ocular and nasal discharges progress from serous to
mucopurulent.
5) Normal lung sounds are difficult to hear expect in
calves, goats and sheep. The heavy chest wall of larger
cattle makes it difficult to hear normal airway sounds.
6) By auscultation o f the anterior ventral lung fields
reveals crackles and wheezes and an increase in
bronchial sounds especially on inspiration.

17. 7) When ventral consolidation
occurs, rough tracheal breathing is
still audible ventrally. Pneumonia
are present in three forms:
(1) Acute lobar pneumonia.
(2) Acute lobular pneumonia.
(3) chronic interstitial
pneumonia.

18. Acute Lobar Pneumonia (Croupous
pneumonia)
Definition
It is the affection of the whole or the greater part of one
lobe of the lung. If the two lobes are affected, it is called
double lobar pneumonia.
•
•Clinical symptoms:
(1) Rapid and shallow respiration.
(2) Short, painful cough.
(3) Inspiratory dyspnea, later on mixed dyspnea in severe
cases.
(4) Engorged eye capillaries and the mucous membranes
are congested then cyanosed.
(5) Sudden rise and continuous fever for about a week then
gradually decreases.

20. (6) Nasal discharge.
(7) The odor o f the breath may be
informative (decay in pus formation
or putrid gangrenous).
(8) The heart is weak and the pulse is
increased.
(9) Percussion and auscultation on
the lung area give abnormal sounds
according to the stages o f
pneumonia.

22. Acute Lobular Pneumonia (Catarrhal or
bronchopneumonia)
•
It is a catarrhal inflammation of bronchi,
bronchioles as well as alveoli (Broncho-
pneumonia). It affects small group of lobules
in one or both lobes o f the lung. It differs from
acute lobar pneumonia in the following points:
(1) Recurrent fever (Specific symptom): It shoots
high and remain for 3 days then drop suddenly
to normal and stay for few days, then shoots
high again and so on, this is due to appearance
o f a new foci o f infection in the lungs.

24. (2) Percussion and auscultation on the
lung area reveal all sounds o f
different stages o f pneumonia in
different areas at the same time, in
addition to the resonant and vesicular
sound as well as rales.
(3) Compensatory emphysema can be
detected by percussion and
auscultation around the affected areas
specially the red consolidation stage.