Veterinary Clinical Medicine-I (General and Systemic)

Respiration and its clinical significance

RESPIRATION

• Examination of respiration is important in diagnosing respiratory system diseases as well as other systemic disorders.
• Rate, rhythm, type and depth should always be noted when assessing the animal’s respiratory movements.
• Rate is the number of respiratory cycles (inhalation, exhalation and rest) in a minute time.
• The rate is counted by noting either the inhalations or exhalations.
• The normal rate of different animals is summarized in table.

Normal respiratory rates in different domestic species

Animal	Range	Animal	Range
Horse	10-14	Dogs	15-30
Ox	10-30	Cats	20-30
Yearling	15-40	Rabbits	30-45
Sheep & Goat	520-30	Camel	5-12
Pigs	8-18

• Exercise and exposure to high atmospheric temperatures increase the respiratory rate as the animal’s body is trying to get rid of excessive heat.
• Pathological conditions that increase the respiratory rates are
  • Fever
  • Various pulmonary diseases
  • Upper respiratory tract diseases
  • Cardiac diseases
  • Pleurisy or peritonitis
  • Anaemia

Some definitions

• Hyperpnoea is the increased pulmonary ventilation (increased respiratory rate with or without increase in the amplitude or width of the movement.
• Polypnoea is increased respiratory rate with reduction in the depth of movements.
• Oligopnoea is reduced respiratory rate. This occasionally occurs in animals suffering from space-occupying lesions of the brain and uremia.

Types of respiration

• Different muscles contribute to the respiratory movement (abdominal muscles, intercostals muscles and the diaphragm).
• When both abdominal and costal muscles are similarly sharing in respiratory movements the type of respiration is termed costo-abdominal. This type of respiration is seen in horses.
• In abdominal respiration, the abdominal muscles predominate in creating the respiratory movement. This type of respiration is evident in cattle.
• The costal muscles are predominant in movement in costal respirations. This type of respiration is evident in dogs and cats.
• The rhythm of respiration is altered in some diseased conditions (advanced renal and cardiac disease, severe toxaemia, menengitis).
• The respiratory depth is also altered in some respiratory disorders (hydrothorax, pneumothorax).

Dyspnoea

• Difficulty in breathing due to diseased conditions is termed dyspnoea.
• Acceleration of the rate of respiration without change in type or depth defines the simple dyspnoea.
• It is often seen in fever, pheumonia, and pulmonary tuberculosis and in some cardiac affections.
• Laboured breathing is called aggravated dyspnoea. Animals suffering from this type of dyspnoea show the following signs

• Widely distended nostrils.
• Open mouth.
• Extension of the head and neck.
• Adduction of the forelimbs.

• Laboured breathing or aggravated dyspnoea can be categorized into inspiratory, expiratory and mixed dyspnoea.
• Inspiratory dyspnoea is observed in severe unilateral paralysis of the pharynx, paralysis or rupture of the diaphragm, advanced cases of pneumonia and bronchitis, stenosis or obstruction of the nasal passages.
• Expiratory dyspnoea is seen when exhalation is made difficult.
• Exaggerated movement of the abdominal muscles is evident in this type of dyspnoea, as animals need more force to expel air from the lungs.
• This occurs in vesicular and interstitial emphysema and chronic bronchitis.
• Mixed dyspnoea is apparent when the respiratory rate is accelerated as well as difficulty encountered during inspiration and expiration.
• This occurs in all severe diseases of the respiratory tract (pneumothorax and hydrothorax) as well as some infectious diseases.