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  • Author or Editor: Jean-Pierre Lavoie x
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Abstract

Objective—To evaluate whether bronchoalveolar lavage (BAL) alters respiratory mechanics of horses with recurrent airway obstruction (ie, heaves) over a 48-hour period.

Animals—6 horses affected with heaves.

Procedures—Horses were subjected to a complete BAL procedure, which included sedation with xylazine and butorphanol, intratracheal administration of lidocaine, and instillation and aspiration of two 250-mL boluses of saline (0.9% NaCl) solution through an endoscope (study 1). To evaluate the effects of saline solution, horses were subjected to the same procedure without saline solution instillation and aspiration (study 2). Lastly, the endoscope was similarly introduced into the lower airways, without sedation or saline instillation and aspiration (study 3). Respiratory mechanics were performed at baseline (time 0) and at 3, 6, 12, 24, and 48 hours after each procedure.

Results—In study 1, BAL induced a significant decrease in pulmonary resistance lasting up to 6 hours. This may have resulted from clearance of mucus in large airways. We also observed a significant increase in lung elastance and transpulmonary pressure at 12 hours after BAL in all 3 studies, which may be attributed to a circadian effect.

Conclusions and Clinical Relevance—Our results indicate that the temporal effects of BAL procedures on lung mechanics should be taken into account when designing research protocols involving horses with heaves. Future studies should address the immediate effects of BAL on lung function.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate effects of thrombophlebitis of 1 or both jugular veins on athletic performance of horses.

Design—Retrospective case series.

Animals—91 horses with jugular vein thrombophlebitis.

Procedures—Medical records of horses with jugular vein thrombophlebitis examined between 1988 and 2005 were reviewed for signalment, history, clinical signs, diagnosis, and treatment. Performance was evaluated in 2 ways. A questionnaire was used to obtain a subjective assessment from the owner or trainer of the horse's performance after thrombophlebitis, compared with the performance before thrombophlebitis. Racing records from before and after thrombophlebitis were also evaluated.

Results—Thrombophlebitis was diagnosed in 37 horses at the time of admission (group 1), and 54 horses developed thrombophlebitis during hospitalization for an unrelated medical condition (group 2). Twenty-seven of 81 (33%) owners answered the questionnaire, and racing records were available for 31 horses. Performance data were available for 48 horses. Owners reported that all nonracing horses, except 1, had equivalent or better performances after discharge. Twenty-six of 31 (84%) Standardbreds resumed racing; in these horses, there was no significant difference between racing times before and after thrombophlebitis. No significant difference in performance was detected regardless of the primary disease, whether a horse had unilateral or bilateral thrombophlebitis, or the treatment administered.

Conclusions and Clinical Relevance—Results suggested that the athletic performance of horses used for nonracing events was not affected by thrombophlebitis. Thrombophlebitis in racing Standardbreds was associated with a decreased chance of return to racing; however, performance was not impaired in those that resumed racing.

Full access
in Journal of the American Veterinary Medical Association

Summary

Effects of triamcinolone acetonide (ta) on pulmonary function, bronchoalveolar lavage cytologic features and serum cortisol concentration, were studied in 5 control horses and 5 horses with chronic obstructive pulmonary disease (copd). In experiment 1, horses were brought in from pasture 3 weeks before administration of 1 injection of ta (0.09 mg/kg of body weight, im), and were stabled in dusty conditions throughout the experimental period. Measurements of respiratory rate (f), tidal volume, minute ventilation, expiratory-to-inspiratory time ratio, maximal change in transpulmonary pressure (ΔPL), pulmonary resistance (RL), and dynamic compliance (Cdyn) were obtained during quiet breathing, immediately before (baseline) and 1, 2, 3, 5, and 9 weeks after administration of ta. Pulmonary airway cells were collected by bronchoalveolar lavage while horses were at pasture, at baseline, and 2, 5, and 9 weeks after ta administration. Serum cortisol concentration was measured before and after adrenocortical stimulation with 100 IU of adrenocorticotropic hormone, 1 week prior to ta administration, and 4 and 8 weeks thereafter. In experiment 2, 4 months after ta injection, pulmonary function measurements were repeated in all horses immediately before and 30 minutes after administration of atropine (0.015 mg/kg, iv), to evaluate the reversibility of airway obstruction.

In experiment 1 at baseline, COPD-affected horses had significantly (P < 0.05) higher values than did controls for f, ΔPL, RL, and percentage of neutrophils, and had lower values for Cdyn and percentage of lymphocytes and macrophages. There were significant reductions in ΔPL and RL, and increase in macrophage percentage after ta administration in copd-affected horses only. The degree and duration of these changes varied among individual copd-affected horses, but ΔPL, and RL, values had returned to or were above baseline in all horses 5 weeks after treatment. Baseline cortisol concentration was decreased 4 weeks after ta administration, but the mean increase in cortisol values after adrenocorticotropic hormone stimulation was similar to that observed prior to treatment.

In experiment 2, values of ΔPL, RL, and Cdyn, after atropine administration were similar to those of controls in the 2 copd-affected horses that had improved most after ta, but were only partially improved in the 3 other horses, indicating possible irreversible lesions in the latter.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine variations in cytologic counts of bronchoalveolar lavage (BAL) fluid attributable to month of collection, first and second aliquots, and left and right lung sites in horses with recurrent airway obstruction (RAO).

Animals—5 horses with RAO and 5 healthy horses without respiratory tract disease.

Procedures—Horses were housed in a stable for 5 months prior to and throughout the study. Bronchoalveolar lavage fluid was collected from the right and left lung of each horse 3 times at monthly intervals (February, March, and April). Each BAL fluid collection was performed by use of 2 incremental instillations of 250 mL of isotonic saline (0.9% NaCl) solution in the same bronchial site. Analysis of BAL fluid included volume of BAL fluid recovered, a CBC, and differential cytologic counts.

Results—Volume of BAL fluid recovered and cytologic counts did not differ in horses with RAO across time or between right and left lungs, except for the number of mast cells. Horses with RAO had significantly lower volumes of BAL fluid recovered, significantly lower percentages of macrophages and lymphocytes, and significantly higher percentages of neutrophils than did healthy horses. Despite individual variation, all horses with RAO had > 25% neutrophils throughout the study period.

Conclusions and Clinical Relevance—Despite variation among horses, BAL fluid cytologic counts were repeatable over short and long periods and samples can be used for longitudinal studies as a diagnostic tool of pulmonary inflammation in horses with RAO.

Full access
in American Journal of Veterinary Research

Abstract

Objectives

To determine temporal variations of pulmonary function in horses without respiratory tract disease (controls) and horses with chronic obstructive pulmonary disease (COPD) and determine whether reversibility of airway obstruction after environmental control can be predicted by response to atropine administration.

Animals

7 COPD-affected and 5 control horses.

Procedures

Pulmonary function testing was performed monthly during 3 consecutive months, daily for 5 consecutive days, and at 6-hour intervals for 24 hours before and after administration of atropine (0.02 mg/kg of body weight, IV) and after 5 consecutive months at pasture. Respiratory rate, tidal volume (VT), minute ventilation (VE), maximal change in transpulmonary pressure (ΔPL), pulmonary resistance (RL), and pulmonary elastance (EL) were calculated.

Results

COPD-affected horses had a significantly higher expiratory to inspiratory time ratio (TE/TI) and ΔPL, EL, and RL than horses without respiratory tract diseases during all periods and higher VE during monthly and daily evaluations. Daily variation in VT and monthly and circadian variation in EL were significant in COPD-affected horses. In control horses, significant changes were apparent only in TE/TI during daily recordings. In COPD-affected horses, reduction in ΔPL, RL, and EL was significant after atropine administration and after maintenance on pasture.

Conclusions and Clinical Relevance

Despite variations in measurements of respiratory mechanics in both groups of horses, values remained significantly different between groups over time. Despite individual variation, measurements were repeatable during short and long periods. Response to administration of atropine to COPD-affected horses underestimated improvement in respiratory tract function that resulted from maintenance on pasture. (Am J Vet Res 1999;60:1341–1346)

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To investigate indicators of neutrophil activation in the blood of healthy and asthma-affected horses and assess associations between corticosteroid treatment and these variables.

ANIMALS

48 horses (14 with severe equine asthma [SEA], 21 with mild to moderate equine asthma [MEA], and 13 healthy controls).

PROCEDURES

In a 3-part retrospective study, hematology analyzer data for horses included in previous studies were reviewed. Neutrophil size, neutrophil light absorbance (NLA), and myeloperoxidase (MPO) index were recorded. Data for each variable were compared among groups for the entire study sample (part 1). Changes in each variable were assessed for one subset of horses (5 SEA-affected and 6 controls) after treatment for 2 weeks with dexamethasone (0.06 mg/kg, PO, q 24 h; part 2) and for another subset (8 SEA-affected horses) after the same treatment and after a 1-week post-treatment washout period (part 3).

RESULTS

All 3 variables were significantly greater for the SEA group, compared with the MEA and control groups in part 1. Following dexamethasone treatment, the control- and SEA-group NLA and MPO index significantly decreased and SEA-group neutrophil size significantly decreased in part 2; immediate posttreatment results for SEA-affected horses were similar in part 3, with significantly increased neutrophil size and nonsignificant increases in NLA and MPO index following washout.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested horses with exacerbated SEA have larger neutrophils that contain more MPO, compared with neutrophils of MEA-affected and healthy control horses. The clinical value of these variables for the diagnosis of equine asthma was deemed limited owing to data overlap among groups. (Am J Vet Res 2021;82:737–745)

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To determine the effects of pentoxifylline (PTX) administration on lung function and results of cytologic examination of bronchoalveolar lavage fluid in horses affected by recurrent airway obstruction (RAO).

Animals—10 RAO-affected horses.

Procedures—6 horses were orally administered PTX (16 g) mixed with corn syrup, and 4 horses were administered corn syrup alone, twice daily for 14 days. Pulmonary function was evaluated before administration (day 0) and on days 8 and 15. Bronchoalveolar lavage (BAL) was performed on days 0 and 15. Reversibility of airway obstruction was assessed by measuring pulmonary function before and after administration of atropine (0.02 mg/kg, IV). Serum concentration of PTX was measured in 4 horses 30 minutes and 2 and 4 hours after administration of PTX on days 1, 2, 3, 7, and 14.

Results—Administration of PTX to RAO-affected horses resulted in a decrease in elastance value on day 8 and on elastance and resistance (RL) values on days 8 and 15. Results for cytologic examination of BAL fluid obtained on day 15 did not differ significantly, compared with values for day 0. Values of RL decreased in all horses following administration of atropine. When mixed in corn syrup and administered orally, PTX was poorly absorbed in horses, and there was noticeable variation in serum PTX concentrations over time and among horses.

Conclusions and Clinical Relevance—Based on these results, it can be concluded that administration of PTX at high doses improved respiratory function of RAO-affected horses maintained in an unfavorable environment. (Am J Vet Res 2002;63:459–463)

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

Neutrophilic inflammation is associated with the degree of airway obstruction in severe equine asthma (SEA), but the contribution of these leukocytes to bronchial remodeling remains ill defined. Neutrophils could cause structural alterations of the airways by the release of exosomes, a type of cell-derived nanoparticles that can modify the biology of local and distant cells. Neutrophil-derived exosomes have been shown to increase airway smooth muscle (ASM) cell proliferation in humans and horses. Therefore, this study aimed to identify neutrophil exosomal microRNAs (miRs) implicated in the regulation of ASM biology in SEA.

ANIMALS

6 horses with SEA and 6 healthy controls.

METHODS

The expression of selected miRs in exosomes from peripheral neutrophils was studied by quantitative PCR. The effects of miR-21 transfection in ASM cells were evaluated by gene expression analysis and proliferation studies.

RESULTS

The miR-21 was downregulated in neutrophil exosomes from SEA horses, and it attenuated the proliferation of ASM cells stimulated with lipopolysaccharide.

CLINICAL RELEVANCE

The lower level of miR-21 in neutrophil-derived exosomes could contribute to ASM hyperproliferation, which could, in turn, promote the thickening of the bronchial wall in SEA.

Open access
in American Journal of Veterinary Research