Pneumonia: Inflammation of the Lung Parenchyma
Pneumonia is the inflammation of the lung parenchyma. It is usually accompanied by inflammation of the bronchioles and may get complicated with the extension of infection to the pleura, leading to pleurisy.
Etiology
Etiology of Pneumonia in Cattle
- Pneumonic pasturellosis (Pasturella haemolytica)
- Haemophilus somnus, Klebsiella pneumonia, Mycobacterium tuberculosis var bovis, Mycoplasm mycoides var bovis, Fusobacterium necroporous, and other microorganisms include Actinomyces pyogenus, Streptococci spp., and Bedsomnia spp.
- Viral agents like rhinovirus, bovine herpes virus, bovine respiratory syncytial virus, para-influenza 3, adenovirus 1, 2, 3, etc.
- Chlamidia and Aspergillus fumigatous are fungal agents.
- Lung worm like dictyocaulus viviparus
Etiology of Pneumonia in Horses
- Streptococcus spp, pasturella spp, E.coli, actinobacillus equi, corynibacterium equi, bacteroids spp
- Viruses like adino, equine herpis virus 1, equine influenza, African horse sickness, etc.
- Lung worms like Dictyocallus arnfieldi
- Pneumonia associated with pulmonary hydatidosis sequale of strangles.
Etiology of Pneumonia in Pigs
- Pasturella spp., Mycoplasma spp., Actinobacillus pleuropneumoniae, etc.
- Lungworm metastrongylus apri
Etiology of Pneumonia in Sheep & Goats
- Pasturella haemolytica, Strepto zooepidemicus, Salmonella abortus, Salmonella ovis, and Pseudomonas pseudomallei
- Maedi, Visna, and Jaag Siekte virus and PPR virus
- Lung worm (dictyocaulus filaria)
Pathogenesis
Lungs are protected by pulmonary defence mechanisms, which consist of the following:
- Mucociliary defence:mucous secreted by the respiratory mucosa acts to entrap the particulate matter in the inhaled air. Ciliary mucosa lining the respiratory tract is unidirectional and thus does not allow particulate matter to move towards the lower respiratory tract. It has been observed that particles larger than 5 micrometres in size are removed by gravitational settling on the mucous surface, whereas smaller particles less than 2 micrometres settle down through diffusion, and alveolar macrophages play an important role in clearing them.
- Bronchus associated lymphoid tissue (BALT) plays an important role in cell mediated as well as humoral immune responses in the form of activation of IgA, mucosal antibody cover, and macrophage activation for the elimination of invading pathogens. The pathophysiology of all types of pneumonia is based on interference with gaseous exchange between alveolar air and blood, which results in anoxia and hyperpnea. This is manifested clinically by polypnea, dyspnea, or tachypnea. Later, a consolidation of the lungs brings about a change in the quality of breath sounds. Depending on the type of exudates,there will be evidence of crackles and wheezes on auscultation. Toxaemia in bacterial pneumonia can be a life-threatening clinical emergency.
Clinical Findings
Rapid, shallow breathing is the initial cardinal sign of pneumonia, which changes to dyspnea in later stages, which is suggestive of much of the lung parenchyma. The nonfunctional presence of a moist, soft, but painful cough is suggestive of bacterial pneumonia. where dryness, hacking, and parxysomal cough are indicative of viral etiology. bilateral mucopurulent nasal discharge, fever, rough hair coat, and the presence of crackles or wheezes on auscultation are observed.
Diagnosis
Clinical findings
The diagnosis of pneumonia can be made based on the clinical findings listed above.
Laboratory investigation
Isolation and identification of the causative agent from the nasal swab, transtracheal aspirate, or balt.
Haematological investigation can be used:
- Leucopenia suggests viral involvement.
- Leucocytosis in the bacterial involvement of peumonia
- Prominent eosinophilia (>20%) suggests a parasitic infection.
The detection of a lung worm larve in faecal sediments suggests verminous pneumonia. Medical imaging techniques and thoracic radiography are helpful in detecting opaque patechae suggestive of consolidation of the lungs. Ultrasonography has also been proven useful in diagnostic aid in detecting abscessation and anaerobic bacterial pleuropneumonia.
Treatment
After seeing the origin of peumonia in animals, the following treatment is followed by symptomatic treatment.
- Bacterial: ampicillin, amoxicillin, tetracycline, and sulphonamide
- Parasitic: levamisole, fenbendazole
- Fungal: amphotericin-b 0.5 mg/kg body weight and supportive treatment.