VPB 121: Veterinary Physiology - II (2+1)

RESPIRATORY FREQUENCY

• Respiratory frequency refers to the number of respiratory cycles each minute.
• It is an excel­lent indicator of health status, respiratory frequency can be affected by other factors, such as:
  • body size,
  • age,
  • exercise,
  • excitement,
  • environmental temperature,
  • pregnancy, and
  • breed.
• Pregnancy and digestive tract filling increase frequency because they limit the movement of the diaphragm during inspiration.
• When expansion of the lungs is restricted, adequate ventilation is maintained by increased frequency. Thus when cattle lie down, the large rumen pushes against the diaphragm and restricts its movement, and the respiratory frequency is seen to increase.
• It indicates the number of breaths per minute during normal quiet respiratory activity.
• Rate of respiration varies with age, sex, body size, exercise, external environmental temperature pregnancy, fullness of digestive tract, rumination, etc. Pregnancy and fullness of the GI tract increases the frequency because they limit the movement of diaphragm during inspiration.
• Frequency also increases as the environmental temperature rises, to help in the thermoregulation.

Respiratory rate of different animals

Horse	10 – 14 / min (12)
Pig	32 – 58 (40)
Cattle	26 – 35 / min. (29)
Dog	20 – 34 (24)
Fowls	15 – 30 / min
Man	12 – 20
Cat	20 – 40 / min
Rat	97 / min
Sheep & Goat	20 – 34 / min (25)