Examination of respiratory system - II

ROUTINE EXAMINATION OF RESPIRATORY SYSTEM

Nasal discharge and expired air 

  • In healthy animals, small amount of mucous is found in the nasal cavity. In equine, following severe exercise, watery mucous can be seen dripping from the nostrils.
  • Pathologically, may contain detached destroyed tissues, transudate, blood or saliva. Unilateral nasal discharge is seen in unilateral localized affection of the nose or adjacent structure. Bilateral nasal discharge occurs in bilateral affection of the bronchi, diseases of pharynx, oesophagus and stomach (vomiting). 
  • The amount of nasal discharge increases in acute nasal catarrh, malignant head catarrh in rumenants and swine infectious rhinitis. Reduced amount is noted in chronic catarrh of upper respiratory tract (URT), bronchitis and pheumonia and in pulmonary tuberculosis in ruminants.  
  • The consistency depends on the pathological changes; serous discharge which is watery in consistency, colorless, transparent is seen in acute diseases of respiratory tract. Secondary infection may turn it into mucous or mucopurulent discharge.  
  • Seromucoid discharge is slightly more viscous than serous discharge. It maybe colorless or grayish in cases of late stages of acute nasal catarrh or bronchitis and laryngitis. The color is derived from presence of small numbers of leukocytes in the discharge.  
  • Purulent discharge is liquid, non-transparent, yellow or greenish in color. It is present in cases of abscesses opening in the respiratory tract. Bloody discharge is a main sign of trauma of capillaries of URT, pulmonary infarction, haemorrhagic diathesis in horses and in anthrax in ruminants. 
  • All the above-mentioned types of discharge have no characteristic odour except for purulent discharge, which has a characteristic rancid odour.  
  • In pulmonary oedema, haemorrhage and chronic bronchitis, nasal discharge may contain air, which results in the foamy character of the discharge. In diseases or paralysis of the pharynx, nasal discharge maybe mixed with saliva and food particles. 
  • Microscopical examination of the nasal discharge detects epithelial cells, leukocytes, erythrocytes, fibrin, elastic fibers, crystals of fatty acids, parasitic ova, fungi and various microorganisms. Elastic fibers are seen in pulmonary gangrene and opened tuberculous nodules.  

Examination of the nostrils and nasal mucous membranes

  • This is preferably carried out in daylight to facilitate detection of the color of mucous membranes. Nasal mucous membranes may become hyperaemic in acute nasal catarrh (rhinitis).  
  • Cyanosis maybe seen in venous congestion, cardiac insufficiency, dyspnoea, disturbance of gas metabolism accompanying insufficient oxidation of the blood.
  • Anaemia results in pale mucous membranes. Chronic nasal catarrh also results in pale mucous membranes. Jaundice (yellowish discoloration of mucous membranes) is seen in hepatic diseases, acute infectious anaemia and leptospirosis.

Other lesions or abnormalities of nasal mucous membranes

  • Wounds resulting from trauma.
  • Ulcers resulting in loss of epithelial layer and
  • tissue destruction as seen in acute or chronic nasal catarrh or haemorrhagic diathesis in equines. In these cases the ulcers are superficial whereas deep ulcers are seen in glanders.
  • Neoplasia as in sarcoma and carcinoma.
  • Oedema of the nasal cavity in severe diseases (malignant head catarrh in cattle).
  • Facial nerve paralysis in horses results in a change in the shape of nostrils, as they become elongated and drawn downwards.

Examination of the para-nasal sinuses

  • Inspection, palpation and percussion are all useful in examination of para-nasal sinuses. In special cases, rhino-laryngeoscopy and X-rays are also used.
  • Inspection reveals uni- or bilateral enlargement or asymmetry of the head in cases of acute sinusitis. Tumors may also result in asymmetry of sinuses. Rickets and osteomalacia both cause bony deformities.
  • Palpation is useful in determining the sensitivity and consistency of bones. In acute inflammation the examined area is hot and painful.
  • Normal sinuses give tympanic sound on percussion; dull sound is heard if the sinuses are largely filled with exudate, in cases of bone degeneration and tumors.

Examination of the larynx and trachea

  • Inspection is used to detect enlargement of the area of larynx and trachea through edematous swelling. Inflammatory swelling at the area of larynx is seen in cases of severe form of laryngitis, anthrax in ruminants, malignant oedema and atypical forms of strangles in horses.
  • Traumatic pericarditis in ruminants may cause non-inflammatory oedema in the submaxillary space that may extend to the area of larynx and trachea.
  • In sheep, oedematous swelling is often seen in helmenthiasis (Dictycaulus and Fascioliasis).
  • In cases of increased sensitivity of the larynx (laryngitis), cough is induced by applying pressure on the first three tracheal rings. Pressure on tracheal rings results in irritation of the larynx and therefore results in induced cough reflex.
  • Bronchial sound is heard by auscultation over the area of the trachea; this sound is also referred to as tracheal, laryngeal and bronchia sound. In cases of bronchitis or trachitis, the sound is intensified. Stenosis of URT in cases of laryngeal oedema and tumours results in stenotic sounds. If the larynx or trachea is filled with liquid exudate, rales also are heard. The character and strength of rales vary according to the amount and type of exudate.
  • Laryngeoscopy is helpful for detection of tumours, oedema and character of mucous membranes.

Cough

  • This is a reflex action to irritation of respiratory passages due to any cause. Examples of causes or inducers of cough are dust, inspiration of food particles, inflammation of mucosal lining, inhalation of various gases (chlorine or ammonia), or from exposure to cold.
  • Cough described based on strength and character. Strong cough occurs when inspiration is deep. Weak cough occurs in difficult expiration where the animal is unable to cough actively; this is seen in pulmonary emphysema, pneumonia and exudative pleuritis.
  • Character of cough depends on production of exudate and could be described as either moist (productive) or dry (unproductive) cough. Moist cough is seen in acute inflammatory conditions of the respiratory tract where there is accumulation of a large amount of mucous. Dry cough occurs in chronic respiratory diseases or in acute dry bronchitis.
  • Frequency of cough depends on the degree of irritation of mucous membranes; it may be single, continuous or periodic. Cough may also be painful or painless. It is painful in acute laryngitis, tracheitis, bronchitis, pleuritis and peritonitis. In chronic inflammation of URT, cough is painless. However, evaluation of pain in animals is often very difficult as this is a subjective sign.

Examination of sputum

  • Mucous and other inflammatory substances are expelled out of the respiratory system via the mouth or the nostrils following productive cough. These expelled materials are termed sputum.
  • Microscopic or bacteriological examination of sputum is helpful in detection of causative agents of the respiratory infection or disease. Sputum is collected by inducing cough artificially or by introduction of a swab.

Other methods of examination

  • Other methods are also used for examination of the respiratory system such as, X-rays and bronchoscopy. These methods are of great importance in the diagnosis of various forms of pneumonia and pleurisy in all species of domestic animals. Emphysema and tuberculosis are also diagnosed using these methods.
  • Rhinoscopy and laryneoscopy for examination of the nasal cavity and pharynx.
  • Microscopic examination of nasal discharge, swabs, sputum, faeces (lung worm).
  • Paracentesis of thoracic cavity is of value when fluid is present in the thoracic cavity for drainage, treatment and cytological examination.
Last modified: Tuesday, 5 June 2012, 11:18 AM