Pulmonary function changes induced by experimental dichlorvos toxicosis in calves

Clinical and pulmonary function changes induced by intravenous dichlorvos (2,2-dichlorvinyldimethyl phosphate) (DDVP) toxicosis, and reversibility of these changes after atropine treatment were investigated in six Friesian calves one to three months old. From one minute after dosage, all animals showed severe respiratory distress, excitation, weakness, muscle fasciculation and cholinesterase inhibition. Decrease in dynamic lung compliance and arterial oxygen tension and increase in total pulmonary resistance, viscous work of breathing and alveolar arterial oxygen gradient were highly significant (P less than 0.01). On the other hand, body secretions, heart rate, respiratory rate, tidal volume and arterial carbon dioxide tension were not significantly affected by DDVP injection. Atropine promptly and completely reversed these changes, except for muscle fasciculations, central depression and cholinesterase inhibition which disappeared progressively within 24 hours.     

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 oxyten 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.     

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.     

Functional changes induced by necrotic laryngitis in double muscled calves

The effects of necrotic laryngitis on the mechanics of breathing and gas exchange were investigated in five Belgian blue double muscled calves two to three months old. All the animals showed the typical clinical picture of the respiratory syndrome associated with naturally occurring necrotic laryngitis. Highly significant increases in total pulmonary resistance, minute viscous work of breathing and alveolar-arterial oxygen gradient, and highly significant decreases in dynamic lung compliance and arterial oxygen tension were recorded in the infected animals, when compared to reference values for healthy cattle. The ratio of inspiratory to expiratory viscous work of breathing was also significantly increased probably because of a partial collapse of the extrathoracic trachea during inspiration. It was concluded that necrotic laryngitis disturbs pulmonary function to such an extent that it impedes the growing process and predisposes the infected animals to secondary bronchopneumonia and ventilatory failure due to respiratory muscle fatigue.     

Interactions of cold stress and Pasteurella haemolytica in the pathogenesis of pneumonic pasteurellosis in calves: changes in pulmonary function

Thirteen healthy neonatal Holstein calves were cold stressed twice by hosing with cold water for 20 minutes, 12 hours between hosings. Measurements of the pattern of ventilation [tidal volume (VT), respiratory frequency (f), minute ventilation (VMIN), and functional residual capacity (FRC)], gas exchange properties of the lungs [alveolar ventilation (VA), oxygen uptake (VO2), CO2 production (VCO2), dead space ventilation (VD), dead space/tidal volume ratio (VD/VT), arterial oxygen tension (PaO2), arterial CO2 tension (PaCO2) and alveolar-arterial oxygen difference (AaDO2)] and of the mechanical properties of the pulmonary system [dynamic compliance (Cdyn), pulmonary resistance (RL), and total respiratory system resistance (RRS)] were taken. Calves responded to chilling by increasing VO2 and VCO2 necessitating an increase in VA. This was accomplished by increasing VT with reciprocal decreases in f so that VMIN remained constant. There was no change in Cdyn, RL, or AaDO2. Seven of these 13 calves were then exposed to intratracheal inoculation of 2 X 10(9) organisms of Pasteurella haemolytica, the remaining calves serving as controls. Within 1 hour, calves exposed to P haemolytica had increased VMIN, f, VD/VT, and VD. There was a decrease in PaO2 associated with increased AaDO2, but no change in PaCO2, Cdyn or RL. By 3 hours after inoculation, there were pronounced changes in PaO2 and AaDO2, and Cdyn was reduced below base-line values. By 12 hours after inoculation, calves infected with P haemolytica had increased RL and RRS and PaCO2, in addition to the previously mentioned changes. Data from Pasteurella-exposed calves indicate that gas exchange impairment and peripheral lung injury occur rapidly and that increases in airway resistance develop relatively late in the disease.(ABSTRACT TRUNCATED AT 250 WORDS)     

Respiratory mechanics in Standardbred horses with sub-clinical inflammatory airway disease and poor athletic performance

The aim of this study was to investigate and quantify respiratory mechanical dysfunctions in Standardbred horses with both poor performance and bronchoalveolar lavage fluid cytology characteristic of inflammatory airway disease (IAD). A control group of healthy Standardbred horses was compared. Respiratory mechanics and breathing pattern were examined at rest and during hyperventilation induced using a rebreathing method. At rest, respiratory mechanics and breathing pattern were superimposable in both groups. In IAD horses, rebreathing increased ventilation, with larger tidal volumes and lower respiratory frequencies. During hyperventilation, IAD animals showed frequency-dependent dynamic lung compliance, and had greater viscous lung resistance and rate of dynamic work of breathing. As IAD alters pulmonary mechanics, the ventilatory load increases and horses requiring significantly higher energy for breathing may suffer restrictions in their athletic performance. This rebreathing method permits early evaluation of respiratory mechanical dysfunction in poorly performing horses with sub-clinical IAD.     

The effect of clenbuterol on lung function parameters in calves suffering from bronchopneumonia

Pulmonary function testing was performed in calves affected with bronchopneumonia. In these calves respiratory rate, viscous work per litre air and per minute, intrapleural pressure difference, mean inspiratory and expiratory flow rate and ventilation per minute were significantly increased. Total resistance of the lung was just not significantly increased. Dynamic compliance and tidal volume were significantly reduced. The main effect of clenbuterol was a significant increase in dynamic compliance. The reduction in the total resistance of the lung was just not significant. These results indicate that clenbuterol can antagonise, at least partly, the alterations caused by bronchopneumonia.     

The effect of clenbuterol on lung function parameters in calves suffering from bronchopneumonia

Pulmonary function testing was performed in calves affected with bronchopneumonia. In these calves respiratory rate, viscous work per litre air and per minute, intrapleural pressure difference, mean inspiratory and expiratory flow rate and ventilation per minute were significantly increased. Total resistance of the lung was just not significantly increased. Dynamic compliance and tidal volume were significantly reduced.The main effect of clenbuterol was a significant increase in dynamic compliance. The reduction in the total resistance of the lung was just not significant. These results indicate that clenbuterol can antagonise, at least partly, the alterations caused by bronchopneumonia.     

Effects of aerosolized histamine and carbachol in the conscious horse.

Pulmonary function tests were performed in seven conscious, standing horses. Changes in pulmonary mechanics and ventilation volumes were measured after inhalation challenge with saline (baseline), histamine (1% w/v solution for 5 min) and carbachol (0.5% w/v solution for 3 min). Comparisons between baseline and posthistamine values revealed a significant (P less than 0.05) increase in nonelastic work of breathing (Wb), maximum change in transpulmonary pressure (max delta Ppl), and pulmonary resistance (RL), while dynamic compliance (Cdyn) decreased (P less than 0.05). Tripelennamine completely abolished these histamine induced changes suggesting the involvement of H1 receptors. A nonsignificant increase occurred in functional residual capacity. However, the amount of nitrogen retained in the lung at the end of a nitrogen washout test was significantly (P less than 0.05) greater after histamine when compared to baseline values. The effect of carbachol was qualitatively similar to that of histamine, Wb and max delta Ppl increased while Cdyn decreased (P less than 0.05). The increase in lower RL reached statistical significance (P less than 0.05) only at the beginning of expiration (/ 25% VT). The present investigation demonstrates that the physiological measurements of lung function could be carried out in conscious, unsedated horses and that the pulmonary function test methods could be used as a tool for study of drug induced changes in pulmonary mechanics.     

Effects of ketanserin on pulmonary hemodynamics, lung mechanics, and gas exchange in endotoxemic pigs

The effects of ketanserin on pulmonary hemodynamics, lung mechanics, and gas exchange were determined in anesthetized 10- to 14-week-old pigs after they were endotoxemic for 1 or 4.5 hours. Saline solution was given to controls (group 1). Escherichia coli endotoxin (055-B5) was infused IV at a dosage of 5 micrograms/kg for 1 hour (group 2). In group 3, endotoxin was infused at 5 micrograms/kg the first hour plus a continuous infusion of endotoxin at 2 micrograms/kg/hr. Ketanserin, a specific serotonin receptor antagonist, was infused IV (300 micrograms/kg) after pigs were endotoxemic for 1 or 4.5 hours (groups 2 and 3, respectively). At 1 hour of endotoxemia, mean pulmonary artery pressure and pulmonary vascular resistance were increased, and cardiac index was decreased. Ketanserin caused a small attenuation of the increases in mean pulmonary artery pressure and pulmonary vascular resistance, indicating that serotonin may have a small role in the endotoxin response at 1 hour. At 4.5 hours of endotoxemia, mean pulmonary artery pressure, pulmonary vascular resistance, alveolar dead space ventilation, and alveolar-arterial oxygen gradient were increased, and cardiac index and lung dynamic compliance were decreased; ketanserin significantly attenuated the endotoxin-induced changes in cardiac index, mean pulmonary artery pressure, pulmonary vascular resistance, and lung dynamic compliance. Ketanserin also decreased the blood temperature after pigs were endotoxemic for 4.5 hours. However, the endotoxin-induced increases (at 4.5 hours) in alveolar-arterial oxygen gradient and alveolar dead space ventilation were not acutely reversed by ketanserin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Histamine H1, H2 receptor effects on mechanics of ventilation and gas exchange in neonatal calves

The effect of histamine infusion (IV) on pulmonary mechanical and gas exchange properties of healthy neonatal Holstein-Friesian calves was determined. Histamine increased pulmonary resistance and static pressure-volume hysteresis and decreased dynamic compliance, but failed to change static compliance; changes were compatible with constriction of both large and small airways without a change in lung elasticity. Histamine decreased arterial oxygen tension by increasing the alveolar-arterial oxygen difference, probably because ventilation-perfusion inequalities resulted from small airway constriction. The pulmonary mechanical and gas exchange effects of histamine were prevented by pretreatment with the H1 receptor antagonist, tripelennamine, but not with the H2 receptor antagonist, metiamide. The histamine-induced changes in static pressure-volume hysteresis and dynamic compliance were reversed by sighing, and histamine effects on the lung were eliminated by 15 minutes after cessation of histamine infusion.     

Comparative pulmonary mechanics in the horse and the cow

Pulmonary mechanics and lung volumes were measured in horses and cows to determine if differences in breathing pattern between the two species were due to differences in the mechanical properties of the lungs. Tidal volume (VT) was larger in the horses, while the respiratory rate (fR) and minute ventilation (VE) were higher in the cows. The horses often had a double peak in airflow during inspiration and, or, expiration, while the cows had a single peak during expiration. Measured lung volumes were larger in the horses and they had a higher dynamic lung compliance (Cdyn,L), although the static compliance of the lung, chest wall and respiratory system (Cst,L,Cst,w and Cst,rs respectively) did not appear to differ between the two species. The cows had a greater change in maximum transpulmonary pressure (delta PLmax) and an increased nonelastic work of breathing (Wb). However, the pulmonary resistance (RL) did not differ between the two species, thus the higher delta PLmax and Wb in the cows were most likely a function of their higher flow rates. Calculations of the rate of work of breathing (W) indicate that both species breathed at an fR above the minimum W. The fR in the horses was close to the fR predicted for the average minimum muscle force, but the fR in the cows was higher. As the differences in the mechanical properties of the lung do not explain the differences in flow pattern, nor adequately account for the higher fR in the cows, it is suggested that the differences in breathing pattern between the two species is due to differences in the chest wall, particularly the size and shape of the abdomen.     

Effects of environmental control on pulmonary function of horses affected with chronic obstructive pulmonary disease

The effects of environmental control on horses affected with chronic obstructive pulmonary disease was assessed by clinical examination and pulmonary function tests, ie, maximum change in intrathoracic pressure, tidal volume, minute volume, non-elastic work of breathing, dynamic compliance, inspiratory and expiratory flow rates and arterial blood gas analysis. A controlled environment (ie, bedding horses on shredded paper and feeding a complete cubed diet) caused symptomatic COPD affected horses to become asymptomatic within four to 24 days (mean ± sd 8.4 ± 4.8 days). When asymptomatic, their pulmonary function values did not differ significantly from those of normal horses, which indicates that the pathophysiological changes occurring in equine COPD are reversible. The time taken for horses to become asymptomatic correlated significantly with age, duration of illness and severity of disease as adjudged by the non-elastic work of breathing.     

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.     

Pathophysiologic study of 3-methylindole-induced pulmonary toxicosis in immature cattle

In 5 Friesian calves given 3-methylindole (3-MI) (100 mg/kg once a week for 8 weeks, except calf 4, given a 50 mg/kg dose on weeks 3 to 8), pulmonary function (PF) values and arterial blood gas tensions (PaO2 and PaCO2) were measured 24 hours after dosing was done and were correlated with clinical, biochemical, and pathologic changes. Three of the calves (No. 1, 2, and 3) showed acute respiratory distress syndrome 24 hours after the first 3-MI treatment, with a large increase in respiratory frequency, minute viscous work, and PaCO2 and a large decrease in tidal volume, dynamic lung compliance, and PaCO2. They died 36, 38, and 84 hours after dosing. Pulmonary function changes were compatible with the severe pulmonary edema and alveolar damage observed at necropsy. The 2 other calves, after they were given the 1st dose, showed only subacute respiratory distress syndrome with less severe changes in PF values recorded at 24 hours. Furthermore, they became progressively more tolerant to the 2nd, 3rd, and 4th weekly treatments, and showed base-line PF values after the 5th weekly treatment. Pathologic changes were not observed in lung biopsy material from these 2 animals at 2 and at 12 weeks after the 8th (or last) 3-MI treatment.     

Effect of Pasteurella haemolytica-derived endotoxin on pulmonary structure and function in calves

The role of endotoxin in the pathogenesis of acute pneumonic pasteurellosis is uncertain. Recently, we reported that Escherichia coli-derived endotoxin given by airway inoculation fails to induce lung injury in calves. Because Pasteurella haemolytica-derived endotoxin may differ substantially from E coli in its pathogenicity, we repeated these studies with Pasteurella endotoxin. Intratracheal inoculation of P haemolytica endotoxin caused hypoxemia and increased the alveolar-arterial oxygen differences without causing hypercarbia or changes in lung mechanical properties and volumes. In contrast, IV inoculation of endotoxin caused systemic hypotension, leukopenia, gas exchange impairment, increased total pulmonary resistance, and decreased dynamic compliance. Both routes of inoculation increased serum endotoxin concentrations and were associated with areas of pulmonary hemorrhage, edema, and acute inflammation. We concluded that P haemolytica-derived endotoxin is pathogenic by IV and airway routes of inoculation, and therefore differs from E coli endotoxin in its ability to induce lung lesions in calves.     

Physiological effects of experimental verminous bronchitis in Friesian calves.

Pulmonary function values were measured in five Friesian calves of five months of age during the patent phase of an experimental moderate lungworm infection and were compared with the pulmonary function values recorded in four control animals. All the nine calves were free of any previous challenge with Dictyocaulus viviparus and were submitted to the same standardized conditions of body conformation, housing, feeding and procedures for pulmonary function testing. A significant increase of respiratory rate, minute ventilation, total pulmonary resistance and power of breathing and a significant decrease of tidal volume, dynamic lung compliance and PaO2 were observed in the infested animals. The absolute intrapleural pressure values were also significantly more negative. The conclusions of the statistical analysis were almost identical when predicted instead of measured pulmonary function values were used in the control group. The clinical, functional and pathological findings in the infested animals were all consistent with the picture of a lower airway obstructive disease.     

Pulmonary function, ventilator management, and outcome of dogs with thoracic trauma and pulmonary contusions: 10 cases (1994-1998)

OBJECTIVE: To document pulmonary function, ventilator management, and outcome of dogs with thoracic trauma that required mechanical ventilation because of severe pulmonary contusions. DESIGN: Retrospective study. ANIMALS: 10 dogs that required mechanical ventilation because of severe pulmonary contusions caused by blunt thoracic trauma. PROCEDURE: Signalment, historical data, arterial blood gas values, oxygen tension-based indices, ventilator settings, peak inspiratory pressure, positive end-expiratory pressure, tidal volume, and minute ventilation values were retrieved from medical records. RESULTS: All 10 dogs required positive-pressure ventilation because of dyspnea following trauma and had severely abnormal pulmonary function. Survival rate to discharge was 30%. Dogs were categorized into 2 groups; group A included 5 dogs in which pulmonary function improved during ventilation, whereas group B included 5 dogs that were euthanatized because of progressive lung dysfunction (n = 4) or cardiac arrest (1). Mean +/- SD body weight of group-A dogs (30.9 +/- 15.9 kg [68 +/- 35 lb]) was significantly greater than that of group-B dogs (7.6 +/- 1.8 kg [16.7 +/- 4 lb]). Dogs with improved lung function had peak inspiratory pressure that decreased progressively, whereas lung compliance deteriorated in dogs in group B. CONCLUSIONS AND CLINICAL RELEVANCE: Dyspneic dogs with severe pulmonary contusions may require and benefit from positive-pressure ventilation Prognosis is better for dogs that weigh > 25 kg (55 lb).     

Cardiopulmonary effects of a tiletamine-zolazepam combination in sheep

To assess the effects on heart and lung function, a tiletamine-zolazepam (TZ) anesthetic combination was evaluated in 10 Dorset-type ewes. Ewes were randomly allotted to 2 equal groups. Ewes of groups 1 and 2 were given a single bolus of TZ (12 and 24 mg/kg of body weight, IV, respectively) at time zero. Hemodynamic, pulmonary, and ventilation variables were measured at 15-minute intervals to 120 minutes. Blood gas variables were evaluated at 5-minute intervals for the first 30 minutes, then at 15-minute intervals to 120 minutes. In all sheep, TZ administration induced rapid, smooth induction, with gradual and unremarkable recovery. Anesthesia duration was not significantly different between groups (mean +/- SD, 39 +/- 5 and 40 +/- 14 minutes for groups 1 and 2, respectively). Immediate drug effects included apnea, decreased mean arterial blood pressure, and arterial hypoxemia. Cardiac output was significantly decreased in both groups at all times after drug administration. Significant changes in group-1 ewes included increased pulmonary and systemic vascular resistances and decreased inspired minute ventilation, tidal volume, and respiratory airflow. Significant changes in group-2 ewes included increased systemic vascular resistance and decreased pulmonary arterial pressure, inspired minute ventilation, and respiratory airflow. Both drug dosages induced apneustic breathing patterns and caused significant changes in arterial and venous blood hemoglobin concentrations and PCV. Tiletamine-zolazepam is useful for intermediate-duration anesthesia in sheep.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of a demand valve on pulmonary ventilation in spontaneously breathing, anaesthetised horses

The pressure flow characteristics of a demand valve which has been suggested to be suitable for use in anaesthetised horses were determined at a range of flow rates commonly encountered in equine anaesthesia. The resistance of the valve was found to be very much greater than the resistance of normal large animal anaesthetic apparatus or the equine lower respiratory tract. The effects of the valve on pulmonary ventilation were investigated in seven anaesthetised, intubated horses. Respiratory rate and dynamic compliance were unaffected by connection of the valve but mean tidal and minute volumes and peak flow rates were substantially reduced. The change in transpulmonary pressure over the respiratory cycle was doubled and indices of work of breathing increased by a factor of three. It was concluded that the resistance offered by the valve was too great for its use in spontaneously breathing horses to be recommended.