Growth-related changes in the pulmonary function of goats.

Growth-related changes in pulmonary function values were investigated in 20 healthy French Alpine goats, aged between 20 and 550 days, weighing 7-55 kg. Pulmonary ventilation, mechanics of breathing and arterial oxygen tension were measured using standardized techniques and methods adapted for goats of different body sizes. The Ppl values and the tI/tTOT ratio showed no significant changes with age and body size. The ventilation values (Vt, Ve, mVI and mVE) increased linearly with growth. There was a significant correlation of age and body weight with dynamic lung compliance (Cdyn), total pulmonary resistance (RL), viscous work of breathing (Wvis tot) and minute viscous work (Wvis min) throughout the age range studied. Cdyn, Wvis tot and Wvis min increased and RL decreased with age and body weight. Arterial blood gases (PaO2 and PaCO2) did not show significant changes over the age range studied. Regression equations for each pulmonary function parameter are given with body weight as the independent variable. Data for the mechanics of breathing were compared with those elsewhere for cattle, horses, man and dogs.

Respiratory and pulmonary haemodynamic changes during experimental organophosphate poisoning in goats.

Five French Alpine goats received 2 mg kg-1 of dichlorvos (DDVP) by intravenous injection and 0.15 mg kg-1 of atropine sulphate 5-10 min later. Ventilatory mechanics, gas exchanges, pulmonary haemodynamics and pulmonary vascular resistance (PVR) were measured before treatment, 5 min after DDVP injection and 5 min after atropine injection. Within 2 min of DDVP administration, all the goats showed acute respiratory distress, excitation and slight muscle fasciculations. A post-inspiratory pause was recorded in 3 goats. Hypersecretion of saliva or nasal discharge was not observed. Dynamic compliance and heart rate decreased significantly and total pulmonary resistance, pulmonary artery and wedge pressures increased significantly. On the other hand, minute ventilation, arterial oxygen and carbon dioxide tensions were not significantly altered by DDVP. Atropine treatment reversed all the clinical and functional parameters, with the exception of the central nervous and muscular signs, which disappeared within 12 h. It was concluded that experimental DDVP toxicosis induced changes in the mechanics of breathing and pulmonary haemodynamics associated with diffuse bronchoconstriction and cardiac insufficiency respectively.

Mechanics of breathing in goats.

Common pulmonary function tests used in man and domestic mammals were adapted to the goat. Requirements for intrathoracic pressure record and pulmonary function investigation were determined. The elastance of the mid-thoracic portion of the oesophagus was measured in 17 healthy goats. The calculated percentage error in identifying the endoesophageal intrathoracic pressure decreased with somatic growth, and was found to be smaller than 2 per cent for adult goats. The location of the oesophageal balloon catheter used to measure the intrathoracic pressure was standardised. The following regression equation calculated between the length of catheter (Lcat) and the thoracic circumference (TC) was found: Lcat (cm) = 6.19 +/- 0.7163 X TC (cm) (R2 = 0.96). The influence of the dead space of a face mask on respiration pattern and arterial blood gas were studied. There were no significant changes in arterial partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2), pHa, breathing frequency and intrathoracic pressures. The influence of head and neck position was investigated. Upper airway resistance (Ruaw), measured with the head in a normal position did not significantly differ from values obtained with the head in a horizontal position. Ruaw measured with the head in a vertical position was considerably increased. Arterial blood gas tension and pulmonary mechanics were measured to assess the reproducibility of pulmonary function measurements. Variability in blood gas tension, tidal volume and minute volume is small. The variability of peak to peak intrathoracic pressure change (max delta Plp), dynamic lung compliance (Cdyn), total pulmonary resistance (RL) and Rt were relatively large.

Pulmonary function values and growth in Belgian white and blue double-muscled cattle.

Seventy-five double-muscled cattle of the Belgian white and blue breed, two days to 50 months old and weighing 45 to 680 kg, were investigated. Transpulmonary pressure changes, measured with an oesophageal balloon, variations of air flow and volume at the mouth were obtained during spontaneous breathing to calculate pulmonary function data. Oxygen and carbon dioxide tensions in arterial blood were also recorded. Growth related changes of the pulmonary function values were similar to those observed in other bovine breeds. Total pulmonary resistance, specific total pulmonary resistance, viscous work, power of breathing, specific viscous work, respiratory frequency and peak-to-peak change in transpulmonary pressure were greater in Belgian white and blue cattle than in Friesian cattle. In the former, tidal volume, specific tidal volume, lowest transpulmonary pressure during expiration, transpulmonary pressure at the functional residual capacity level, dynamic lung compliance and oxygen tension in arterial blood were smaller. Airflow, minute volume and carbon dioxide tension in arterial blood were similar in the Belgian white and blue and Friesian cattle. These results were related to the great sensitivity of double-muscled cattle of the Belgian white and blue breed to laryngitis and bronchopneumonia.

A comparison of pO2, pCO2, pH and bicarbonate in blood from the carotid and coccygeal arteries of calves.

A technique is described for the subcutaneous deviation of the carotid artery into the jugular groove of calves weighing between 90 and 200 kg. This makes sampling arterial blood or chronic cannulation for further experimentation very easy. Values of oxygen tension, carbon dioxide tension, pH and bicarbonate concentration in blood sampled from the ventral coccygeal artery were compared with the values obtained in blood from carotid artery puncture. The high correlations observed indicate that blood samples from the ventral coccygeal artery can be used for measurement of blood gases and pH in calves.

Partitioning of upper airway resistance in Friesian and double-muscled calves.

Respiratory resistance in calves was partitioned in two components: upper airway resistance and pulmonary resistance. The former one was divided into naso-pharyngeal and laryngeal resistance. A comparison between seven healthy unsedated double-muscled calves of the Belgian White and Blue breed (BWB) and five healthy unsedated Friesian (F) calves was performed. Respiratory resistance was significantly greater in the BWB calves, due to the significantly higher values of the naso-pharyngeal and the laryngeal resistances. This finding might be related to the higher prevalence of laryngitis in this breed.

Partitioning of pulmonary resistance in Friesian calves.

Eight right cranial lobes of healthy Friesian calves were suspended in an airtight box. They were inflated at a constant transpulmonary pressure (Ptp) and ventilated from the outside by modifying pressures in the box with a quasi-sinusoidal pump at a frequency of 30 counts per minute. Peak-to-peak changes were 0.5 kPa. Lobar resistance (Rl) was partitioned into three components: central airway resistance (Rc), small airway resistance (Rp) and tissue resistance (Rt). Partitioning of R1 was realised at six different lung volumes. Minimal R1 was observed for a value of Ptp between 0.5 and 0.7 kPa. At a Ptp of 0.5 kPa, Rc, Rp, Rt represent 30, 15 and 55 per cent of R1, respectively. Lobar resistance increases at high and low lung volumes. Small airway resistance is small and independent of the level of lung inflation, except at low lung volumes where a marked increase is observed. Tissue resistance is relatively high and responsible for the increase of R1 at high lung volumes. Central airway resistance does not change significantly with lung volumes.