Influence of Inertance on Measurements of the Mechanical Properties of the Bovine Respiratory System

in Veterinary Research Communications (1988), 12(1), 61-66

The observation that dynamic compliance (Cdyn) tended to rise with respiratory frequency (f) in adult cattle led us to reassess the importance of inertial pressures in measuring Cdyn in large animals ... [more ▼]

The observation that dynamic compliance (Cdyn) tended to rise with respiratory frequency (f) in adult cattle led us to reassess the importance of inertial pressures in measuring Cdyn in large animals. Five healthy Friesian cows were selected for their ability to show an increase of f without significant change in tidal volume (VT). Dynamic compliance was measured three times, both at the resting f (21 +/- 1 cpm), and at higher f (49 +/- 3 cpm), obtained by an artificial increase in the dead space of the breathing mask. Frequency-response characteristics of the measuring instruments were matched up to 12 Hz. The inertia of the lungs and gas stream (In) was calculated as the ratio of the accelerative pressure change to the simultaneous change in volume acceleration. Inertance was also estimated from the dimensions of the bovine airways and from the relative linear flow velocities reported by Rohrer (1915). Dynamic compliance measured during rapid breathing was significantly higher (p less than or equal to 0.01) than base-line values. Dynamic compliance was strongly correlated with f (r = +0.96). Measured and estimated In were 0.002 and 0.003 kPa.sec2.L-1 respectively. Dynamic compliance did not differ significantly from base-line values when it was corrected for the estimated inertance effect. [less ▲]

Pulmonary Mechanics During Treadmill Exercise in Race Ponies

in Veterinary Research Communications (1988), 12(2-3), 245-258

Exercise-induced variations in their ventilatory mechanics were studied in 8 healthy ponies 4.2 +/- 1.4 years old and weighing 282 +/- 11 kg. Airflow (V), tidal volume (VT), esophageal pressure, mask ... [more ▼]

Exercise-induced variations in their ventilatory mechanics were studied in 8 healthy ponies 4.2 +/- 1.4 years old and weighing 282 +/- 11 kg. Airflow (V), tidal volume (VT), esophageal pressure, mask pressure and electrocardiogram were simultaneously recorded before, during and after a treadmill (incline 8.3 degrees) exercise which consisted of 2 min walking (1.5 m.sec-1), 3 min slow trotting (3.0 m.sec-1) and 3 min fast trotting (3.5 m.sec-1). The results of three consecutive daily measurements were averaged for each pony. Heart rate, minute volume (Ve), respiratory frequency (f) and peak inspiratory and expiratory V, mean inspiratory and expiratory V, and peak to peak changes in transpulmonary pressure (maxdPtp) increased linearly and significantly with increasing velocity (v) (R2 = 0.99). Tidal volume and the inspiratory time to total breathing time ratio showed a curvilinar relation with v (R2 = 0.99). Minute volume, maxdPtp, total pulmonary resistance (RL) and VT increased from rest to fast trot 6.7, 5.7, 1.5 and 1.6 times respectively. When the ponies stopped all these values decreased significantly. After 5 min recovery, the Ve was approximately doubled, VT and max dPtp unchanged and RL 30% smaller than their respective resting values. The exercise-induced increase in Ve was achieved by an increase in f at both low and high intensity of work. [less ▲]

Effect of Environmental Temperature and Relative Humidity on Breathing Pattern and Heart Rate in Ponies During and after Standardised Exercise

in Veterinary Record : Journal of the British Veterinary Association (1988), 123(11), 295-299

A preliminary study attempted to assess the influence of atmospheric conditions on the breathing pattern of ponies. The respiratory airflow, tidal volume, breathing frequency, minute volume, total ... [more ▼]

A preliminary study attempted to assess the influence of atmospheric conditions on the breathing pattern of ponies. The respiratory airflow, tidal volume, breathing frequency, minute volume, total pulmonary resistance and heart rate of five ponies (257 +/- 9 kg and three to five years old) were measured by a standardised procedure. Data were collected at rest, during a nine minute period of treadmill exercise and during a five minute recovery period. The ambient temperature (degrees C) and relative humidity (%) were recorded at the time of each investigation and the respiratory parameters were divided into two groups according to whether the sum of these measurements was less than 85, ie, the conditions were cold and dry or greater than 85, ie, the conditions were relatively hot and humid. Data for each pony in both conditions were compared. The ambient temperature and relative humidity did not significantly modify the breathing pattern of the ponies either at rest or during exercise. On the other hand the frequency of breathing was significantly higher and the tidal volume and total pulmonary resistance were significantly lower during recovery in hot and humid conditions than in cold and dry conditions, while the minute volume remained unchanged. It was concluded that, during recovery, environmental conditions may modify the breathing pattern of horses. This suggests that in hot and humid weather conditions the respiratory rate may be an unreliable measure of the fitness of a horse and, consequently, that a more complete pulmonary investigation should be undertaken for an assessment of fitness. [less ▲]

Effect of Enrofloxacin Therapy on Shipping Fever Pneumonia in Feedlot Cattle

in Veterinary Record : Journal of the British Veterinary Association (1988), 123(8), 205-207

The effect of enrofloxacin therapy was investigated in 110 male double-muscled cattle weighing 275 +/- 3 kg, during a spontaneous outbreak of shipping fever occurring 11 +/- 2 days after they arrived in ... [more ▼]

The effect of enrofloxacin therapy was investigated in 110 male double-muscled cattle weighing 275 +/- 3 kg, during a spontaneous outbreak of shipping fever occurring 11 +/- 2 days after they arrived in the feedlot. Forty-six diseased animals were divided randomly into three groups A, B and C, containing 17, 19 and 10 animals, respectively; the animals in group A were injected intramuscularly once daily for three consecutive days with 2.5 mg/kg of enrofloxacin, those in group B with 5 mg/kg of enrofloxacin and those in group C with 10 mg/kg of oxytetracycline. Clinical, serological, production and respiratory functional observations were recorded. The animals were clinically cured after the three day treatment except for three in group A and two in group C. These five animals made a clinical recovery after a three day booster treatment with a dose of 5 mg/kg enrofloxacin. The changes in respiratory gas exchange values induced by shipping fever were completely reversed 15 days later, suggesting that there had been no irreversible lung damage. The daily weight gains and the arterial blood gas values of the three groups of treated cattle were not significantly different. The high efficacy of the low dosage of enrofloxacin in this clinical syndrome may be explained by its antibacterial activity against Pasteurella species and Mycoplasma species. This field trial supports the in vitro studies which suggested than enrofloxacin is an appropriate therapy in cases of shipping fever. [less ▲]

Study of the airflow patterns in healthy and diseased cattle

in Proceedings of the Sixth Veterinary Respiratory Symposium (1987, November)

Effects of training and detraining on lung ventilation, heart rate and thermoregulation during a standardized treadmill exercise in ponies. A preliminary study

in Proceedings of 6th comparative Respiratory Society Meeting, Chicago (USA) (1987)

Effet des pathologies respiratoires sur la fonction pulmonaire des bovins à l'engraissement

in Annales de Médecine Vétérinaire (1987), 131

Clinical, serological and physiological values were measured during and after naturally occuring respiratory disease in fattening cattle. Clinical and serological findings were in agreement with the ... [more ▼]

Clinical, serological and physiological values were measured during and after naturally occuring respiratory disease in fattening cattle. Clinical and serological findings were in agreement with the description of the Shipping Fever syndrome. Pulmonary function values recorded during the initial stage of the disease showed a significant increase in respiratory rate, total pulmonary resistance, minute viscous work of breathing and alveolo-arterial oxygen gradient and a significant decrease in tidal volume and arterial oxygen tension. None of these values was still abnormal 2 weeks later. It was concluded that moderate Shipping Fever induce an acute obstructive disease located mainly at the level of large airways. On the other hand, the complete reversibility of the clinical and functional changes indicates that accurate preventive and curative treatments may avoid the onset of severe pulmonary dammage and may reduce the economical losses induced by the Shipping Fever syndrome. [less ▲]

High-frequency ventilation in cats: technical data

in 4th Comparative Respiratory Society meeting - Anaheim California - USA (1985)