تنفسي

• Functions of the respiratory system

  • Delivers oxygen to the cardiovascular system
  • Removes carbon dioxide
  • Maintaining acid-base balance
  • The upper airways provide for the sense of smell (olfaction)
  • Filtering and probably destroying emboli
  • Metabolizing some bioactive substances (serotonin, prostaglandins, corticosteroids, and leukotrienes)
  • Activating some substances (e.g, angiotensin)
  • Protects its own delicate airways
  • Plays a role in temperature regulation in panting animals
• Causes of nasal obstruction

  • Tumors
  • Granulomas
  • Abscesses
  • Foreign bodies
• Rhinitis


  Inflammation of the mucous membrane in the nose
• Causes of rhinitis


  • Viral
  • Bacterial
  • Fungal
  • Parasitic
  • Hypersensitivity reactions (allergies and anaphylaxis)
• Allergic rhinitis


  • Marked mucosal edema, redness, and mucus secretion, accompanied by a leukocytic infiltration (eosinophils)

  
• Rhinitis can be mild, with just a bit of clear nasal discharge seen, or it can be severe enough to have green/yellow/hemorrhagic (bloody) discharge

  
• Epistaxis


  Bleeding from nasal passage
• Most likely the underlying lesion is a Ruptured pulmonary artery branch into a bronchiole secondary to septic arteriole embolus/thrombus

  
• Pharyngitis


  Inflammation of the walls of the throat (pharynx)
• Laryngitis


  Inflammation of the larynx, the part of the throat often called the "voice box"
• Nasal granuloma


  Granulomatous inflammation of respiratory mucosa in nasal cavity caused by blood flukes
• Nasal granuloma


  • Small tiny nodules on nasal mucosa later becomes cauliflower like growth filling the cavity and causing obstruction
  • Edema in lamina propria
  • Infiltration of eosinophils, mast cells, lymphocytes and plasma cells and absence of epithelioid cells
  • Proliferation of fibroblasts
  • Lesion is covered by squamous epithelium
  • Mucous glands may have metaplastic pseudostratified columnar epithelium
• Bronchitis


  Inflammation of bronchi, characterized by catarrhal, suppurative, fibrinous or haemorrhagic exudate

  
• Causes of bronchitis


  • Bacteria (e.g. Pasteurella)
  • Virus (e.g. Infectious bronchitis in poultry)
  • Parasites (e.g. Dictyocaulus filaria in sheep/goat, Dictyocaulus viviparus in cattle and deer)
  • Allergy/Inhalation of pollens
• Bronchitis


  • Mucous exudate in lumen
  • Congestion and/or hemorrhages in bronchi
  • Presence of caseous plugs at the point where bronchi enters in lungs in infectious bronchitis of poultry
  • Mucous exudate along with inflammatory cells in the lumen of bronchi
  • Hyperplasia and/or necrosis of bronchiolar epithelium
  • Accumulation of mononuclear cells in the bronchial mucosa and in peribronchiolar area
  • Eosinophilic granulocytes in the peribronchial tissue indicates allergic origin

  
• Bronchiectasis


  Permanent enlargement of parts of the airways, usually a complication of previous lower respiratory infection and/or inflammation

  
• Atelectasis


  Failure of alveoli to open or the alveoli are collapsed and thus do not have air

  
• Atelectasis


  • Dull red in color, hard area of lung like liver in consistency
  • Atelectic lung sinks in water
  • Compressed alveoli
  • Absence of air spaces
  • Collapsed bronchioles
  • In inflammatory condition, exudate compresses alveoli

  
• Emphysema


  Increase in amount of air in lungs characterized by dilation of the alveoli, may be acute or chronic and focal or generalized
• Causes of emphysema


  • Bronchitis
  • Atelectasis in adjoining area of lung
  • Pneumonia
  • Allergy to dust, Pollens
  • Pulmonary adenomatosis

  
• Pneumonia


  Inflammation of one or both lung's parenchyma, often caused by infections
• Causes of pneumonia


  • Bacteria
  • Viruses
  • Fungi
  • Parasites
• Stages of lobar pneumonia

  1. Congestion: Pulmonary parenchyma not fully consolidated, alveoli have serous exudates, pathogens, few neutrophils, and macrophages

  2. Red hepatization: Lobe consolidated, firm, and liver-like, with addition of fibrin along with serous exudate, pathogens, neutrophils, and macrophages, congested capillaries, and thickened alveolar walls

  3. Gray hepatization: Lobe still liver-like in consistency but gray in color due to suppurative and exudative filled alveoli

  4. Resolution: After a week, lymphatic drainage or productive cough clear the exudate

  
• Classifications of pneumonia


  • Durational: Acute pneumonia, Chronic pneumonia
• Acute pneumonia


  • Characterized by congestion and consolidation of anterior and ventral parts of lungs (Lobular pneumonia)
  • Patchy lesions on one or several lobes and adjacent area shows emphysema
  • Mediastinal lymphnodes are swollen
  • Congestion, oedema or haemorrhage in lung
  • Infiltration of neutrophils, mononuclear cells in and around bronchioles/ bronchi
  • Catarrhal inflammation of bronchi
  • Proliferation of bronchiolar epithelium

  
• Interstitial pneumonia


  • Inflammation of the lungs characterized by thickening of alveolar septa due to serous/ fibrinous exudate along with infiltration of neutrophils and/or mononuclear cells and proliferation of fibroblasts

  
• Verminous pneumonia


  • Caused by parasites and characterized by the presence of lesions of broncho-pneumonia along with parasites or their larva
• Aspiration pneumonia


  • Caused by faulty medication through drenching which reaches in lungs instead of target place (digestive track) and characterized by necrosis and gangrene of lung parenchyma

  
• Fibrinous pneumonia


  • Inflammation of lungs characterized by the presence of fibrin in alveoli or bronchioles and may give rise to hyaline membrane formation over the surface of alveoli or bronchiole
  • Antero-ventral portion of lung is congested and consolidation
  • Color of lungs become deep red due to congestion
  • Surface of lungs is covered by fibrin sheet
  • Interlobular septa are prominent due to accumulation of plasma and fibrin
  • Principal exudate is fibrin, fills alveoli, bronchioles and bronchi
  • Congestion and/ or haemorrhage
  • Infiltration of neutrophils, macrophages and giant cells
  • Formation of eosinophilic false membrane of fibrin over the surface of alveoli and bronchiole and then known as "Hyaline membrane pneumonia"

  
• Tuberculous pneumonia


  • Caused by Mycobacterium sp. and characterized by the presence of chronic granulomatous lesions in the lungs
  • Grey, white or light yellowish nodules in lungs
  • Nodules are hard, painful and/or calcified
  • Animal carcass is cachectic, weak or emaciated
  • On cut, the cheesy material comes out from the nodules
  • Presence of tubercle/ granuloma in lungs which comprises a central necrosed area surrounded by macrophages, epithelioid cells, lymphocytes, Langhan's giant cells and covered by fibrous covering
  • Acid-fast rod-shaped bacteria may present in necrosed area
  • Central area may be calcified

  
• Ovine pulmonary carcinoma (Pulmonary adenomatosis)

  • Contagious lung tumour which can be transmitted experimentally with tumour homogenates or the copious secretions (SPA lung fluid) that accumulate in the respiratory tract, particularly during the terminal stages of the disease
  • Metaplasia of alveolar squamous epithelium to cuboidal and/ or columnar epithelium leading to glandular appearance of alveoli
  • Multiple focal areas of consolidation in lungs
  • Imprint of ribs on lungs
  • Congestion and hardening of mediastinal lymphnodes
  • Metaplasia of alveolar epithelium leading to formation of glandular structures in alveoli
  • Metaplasia of simple squamous epithelium to cuboidal or columnar epithelium which gives alveoli a gland like look
  • Mild inflammatory reaction
  • Proliferation of fibrous tissue

  
• Pleuritis


  • Inflammation of pleura characterized by serous, fibrinous or purulent exudate
  • Congestion of pleura
  • Serous, fibrinous or purulent exudate
  • Accumulation of clear fluid in pleural thoracic cavity is called as hydrothorax
  • Presence of blood in the thoracic cavity known as Hemothorax
  • Suppurative exudate in thoracic cavity is known as pyothorax
  • Presence of air in pleural cavity is termed as pneumothorax, while presence of lymph in pleural cavity is called as chylothorax

  
• Tuberculous pleuritis


  • Characterized by small nodules on pleura and is known as "pearly disease"
  • In chronic cases, development of fibrous tissue causes adhesions and is known as adhesive pleuritis
  • Congestion of blood vessels
  • Infiltration of neutrophils and lymphocytes
  • Thickening of pleura due to oedema
  • Proliferation of fibroblasts producing adhesive lesions

  
• Some tumors of respiratory system

  • Osteogenic sarcoma
  • Lymphosarcoma
  • Malignant melanoma
  • Nasal multifocal mycotic granulomatosis
  • Squamous cell carcinoma of nasal sinus
  • Metastatic fibrosarcoma
  • Metastatic chondrosarcoma
  • Hemangiosarcoma