The effect of topical treatment on esophageal pH during acid reflux in dogs

OBJECTIVE: To determine the effect of suction, lavage and instillation of sodium bicarbonate solution on esophageal pH during acidic gastro-esophageal reflux (GER) in anesthetized dogs. STUDY DESIGN: Prospective, clinical trial. ANIMALS: Ten healthy dogs, 4.8 +/- 2.4 years old, and weighing 37.1 +/- 7.9 kg. METHODS: Dogs were admitted to the study if they were under general anesthesia and regurgitation occurred. A sensor-tipped catheter was used to measure esophageal pH. On study entry the esophagus was suctioned. After an interval of at least 5 minutes, if the esophageal pH was still less than 4 the esophagus was lavaged with tap water and again suctioned. In 6 dogs 20 mL of dilute bicarbonate solution was instilled into the esophageal lumen. RESULTS: Suctioning fluid from the esophagus did not change the pH significantly. Lavage with tap water caused the pH to increase above 4 in four dogs, with the average pH increasing from 1.2 +/- 0.5 to 3.5 +/- 4.9. In all dogs where dilute bicarbonate solution was instilled, esophageal pH increased to above 6 for up to 180 (mean +/- SD, 89 +/- 81) minutes. CONCLUSIONS AND CLINICAL RELEVANCE: Suctioning refluxate from the esophagus does not change the pH of the esophageal lumen. Instillation of a small volume of bicarbonate solution predictably increased the pH above 4 following an episode of acidic GER. Care must be taken that fluid is instilled into the lumen of the esophagus, and not into the trachea.     

Unguided bronchoalveolar lavage techniques and residual effects in dogs

Objectives To investigate the use of unguided bronchoalveolar lavage techniques in dogs without fibreoptic bronchoscopy, using an adapted single vascular catheter and a double-lumen catheter made from two single vascular catheters.
Animals Sixty-nine dogs were examined with the single-catheter technique and 110 dogs with the double-catheter technique.
Design A prospective study.
Procedure Sixty-nine and 220 samples, collected with the single catheter and the double catheter respectively, were examined cytologically Lungs of 69 dogs were examined grossly and histologically. Radiographic examination was performed on 11 dogs.
Results The double-catheter technique produced samples with significantly higher cellularity (P < 0.01) and fewer red blood cells (P < 0.01) than the single-catheter technique. Repeat samples collected with a double catheter were not significantly different (P > 0.01) in any value. A reference range for nucleated cell counts of 62 to 1210 – 10⁶/L was calculated from 57 clinically and histologically normal dogs. The major residual effects of the technique were localised pulmonary oedema, and alveolar distension with collapse and congestion of distant parenchyma. Thoracic radiographs revealed increased lung opacity for at least up to 7 h after the procedure.
Conclusions The cellularity of the bronchoalveolar lavage fluid obtained was adequate and sufficient fluid was retrieved when the single catheter was located in a proper position. However, the double catheter obtained better samples more quickly and easily, with less damage to the respiratory tract.     

Influence of Age on Surfactant Isolated from Healthy Horses Maintained on Pasture

Background: Surfactant alterations are described in horses after exercise, anesthesia, and prolonged transport, in horses with recurrent airway obstruction, and in neonatal foals. The effect of horse age or bronchoalveolar lavage fluid (BALF) sample characteristics on surfactant is unknown.
Objectives: To evaluate surfactant phospholipid composition and function in healthy horses, and to investigate the influence of age and BALF sample characteristics on surfactant.
Animals: Seventeen healthy horses 6–25 years of age maintained on pasture year-round.
Methods: BALF was collected by standard procedures and was assessed for recovery volume, nucleated cell count (NCC), and cytology. Cell-free BALF was separated into crude surfactant pellet (CSP) and surfactant supernatant (Supe) by ultracentrifugation. Phospholipid and protein content were determined from both fractions. CSP phospholipid composition was analyzed by high-performance liquid chromatography with an evaporative light scatter detector. Surface tension of CSP was evaluated with a pulsating bubble surfactometer. Regression analysis was used to evaluate associations between age, BALF sample characteristics, and surfactant variables.
Results: Results and conclusions were derived from 15 horses. Increasing age was associated with decreased phospholipid content in CSP but not Supe. Age did not affect protein content of CSP or Supe, or surfactant phospholipid composition or function. Age-related surfactant changes were unaffected by BALF recovery percentage, NCC, and cytological profile.
Conclusions and Clinical Importance: Older horses have decreased surfactant phospholipid content, which might be because of age-related pulmonary changes. Surfactant composition is unaffected by BALF sample characteristics at a BALF recovery percentage of at least 50%.     

Bronchodilators in bronchoscopy-induced airflow limitation in allergen-sensitized cats

This study investigated the effect of bronchoscopy and bronchoalveolar lavage (BAL) on respiratory function, determined by barometric whole-body plethysmography (BWBP), of healthy and allergen-sensitized cats. Furthermore, the efficacy of inhaled bronchodilators in preventing changes in respiratory function was determined. For test 1, 18 healthy experimental cats were investigated on day 1 by BWBP. On day 2, the cats underwent BWBP after sedation (medetomidine), after anesthesia induction (propofol), and after bronchoscopy and BAL. Enhanced pause (Penh) was significantly increased after bronchoscopy and BAL (1.64 +/- 0.17 versus 1.23 +/- 0.07, P < .05). For test 2, 6 cats were sensitized to ovalbumin (OVA), 6 cats were sensitized to Ascaris suum (AS), and 6 cats served as controls. On day 0, OVA- and AS-sensitized cats underwent an inhaled allergen challenge, whereas controls were exposed to saline. On days 1 and 2, the same protocol as described for test 1 was repeated. Post-BAL Penh of the AS-sensitized cats was significantly higher than at test 1 (2.28 +/- 0.22 versus 1.69 +/- 0.33, P < .05) and was correlated with BAL fluid neutrophil count (r = 0.55, P < .05). During tests 3, 4, and 5, the same protocol as used for test 2 was applied to each cat group, with the animals being randomly treated before sedation with inhaled salbutamol (200 microg), ipratropium bromide (40 microg), or a combination of both (200 + 40 microg). Post-BAL Penh of the AS-sensitized group was significantly decreased after the salbutamol + ipratropium bromide treatment (1.56 +/- 0.18 versus 2.28 +/- 0.22, P < .05). This study suggests that bronchoscopy and BAL induce airflow limitation in cats, which is more severe in the presence of lower airway inflammation. Inhaled salbutamol + ipratropium bromide reduce BAL-induced bronchoconstriction in AS-challenged cats and might be recommended as preventive treatment of asthmatic cats undergoing bronchoscopy.     

Clinical, bronchoscopic, histopathologic, diagnostic imaging, and arterial oxygenation findings in West Highland White Terriers with idiopathic pulmonary fibrosis

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic, interstitial lung disease primarily affecting West Highland White Terriers (WHWTs). Objective: To describe the clinicopathological and diagnostic imaging features in WHWTs with IPF. Animals: Twelve WHWTs with IPF and 14 healthy control WHWTs. Method: Prospective study. Clinical signs and findings of physical examination, blood and arterial blood gas analyses, radiography, high‐resolution computed tomography (HRCT), bronchoscopy and bronchoalveolar lavage (BAL) of IPF dogs were obtained and compared with controls. Histopathologic changes in IPF dogs were evaluated. Results: Mean partial pressure of oxygen was significantly lower in IPF (mean ± SD, 65.5 ± 15.4 mmHg) than in controls (99.1 ± 7.8 mmHg, P<.001). The alveolar‐arterial oxygen gradient was significantly higher in IPF (50.1 ± 17.3 mmHg) than in controls (17.5 ± 4.9 mmHg, P<.001). In HRCT, ground glass opacity (GGO) was detected in all IPF dogs, traction bronchiectasis in 4, and honeycombing in 1. Bronchoscopic airway changes were noted in all IPF dogs. On BAL fluid (BALF) cytology, the total cell count (TCC) was higher in IPF dogs, and the numbers but not the percentages of macrophages, neutrophils, and mast cells were increased. On histopathology, multifocal or diffuse interstitial fibrosis, type II pneumocyte hyperplasia, prominent intraalveolar macrophages, distortion of alveolar architecture, and emphysematous change were detected. Conclusion and Clinical Importance: IPF causes substantial hypoxemia. In HRCT, GGO is a consistent finding. IPF dogs have concurrent airway changes and an increase in BALF TCC.     

Responses of Guinea-Pig Lung Parenchymal Strips to Tracheobronchial Lavage Fluid from Horses affected with Summer Pasture-Associated Obstructive Pulmonary Disease

The response of parenchymal strips from guinea-pig lungs to tracheobronchial lavage fluid (TBLF) collected from 8 normal horses and from 8 affected with summer pasture-associated obstructive pulmonary disease (SPAOPD) was determined. TBLF was collected during the summer (July) and winter (February) seasons. The serum/TBLF urea nitrogen ratio was used to standardize the mediator concentration in the TBLF. Four strips were used from each guinea-pig. The first strip did not receive any antagonist and served as the control. The second, third and fourth strips received antagonists of PGE2, LTD4 and PAF, respectively at 10–6 mol/L for 30 min. The tissues were then precontracted with a dose of histamine (10–5 mol/L) and their responses to 1 ml of TBLF were determined. The study showed that TBLF obtained in the summer from unaffected horses produced a significantly greater relaxation than that from the affected horses, whereas TBLF obtained in the winter from unaffected or affected horses did not cause a significantly different degree of relaxation. Among the antagonist-treated strips, only those exposed to the PGE2 blocker showed a significant reduction in the relaxation caused by TBLF obtained in the summer from SPAOPD horses. This suggests that PGE2 is an important mediator present in the summer in the TBLF from horses affected with SPAOPD.