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.
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
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)
Objective—To evaluate whether the leukotriene (LT)
D4 receptor antagonist L-708,738 is therapeutically
beneficial in treating horses with recurrent airway
Animals—12 adult horses with heaves and healthy
lung lobes from 20 slaughtered horses.
Procedure—Lung lobes were used for smooth muscle
tension and radioligand binding studies. Horses
with heaves were given a placebo for 14 days and
administered L-708,738 (n = 6; 2.5 mg/kg PO, q 12 h)
or dexamethasone (6; 0.04 mg/kg, IV, q 24 h) from
days 14 to 28. Pulmonary function was measured
weekly for 36 days, and bronchoalveolar cells were
collected on days 0, 14, and 29 for cytologic examination.
Results—Nanomolar concentrations of L-708,738
were effective at antagonizing LTD4-induced bronchoconstriction
and LTD4-receptor binding in lung
lobes. Mean peak and trough L-708,738 plasma concentrations
during the treatment period were 1.54 and
0.28 μM, respectively. On days 21 and 29, lung
mechanics were significantly improved in the dexamethasone-
treated horses but not in the L-708,738-treated
horses. Neither dexamethasone nor
L-708,738 had a significant effect on cytologic findings.
Conclusions and Clinical Relevance—L-708,738
was bioavailable after oral administration and sustained
concentrations in plasma during the dosing
period that exceeded in vitro efficacy values.
However, airway function did not improve, suggesting
that either drug concentrations in the lungs were subtherapeutic
or that cysteinyl LT may not be important
mediators of airway inflammation in heaves. Results
provide the first evidence of cysteinyl LT1 receptors in
airways of horses. (Am J Vet Res 2002;63:579–585)
OBJECTIVE To evaluate the mRNA expression of T helper (Th)1, Th2, and Th17 cell–associated inflammatory mediators in cells of bronchoalveolar lavage fluid samples collected from healthy horses exposed to hyperbaric oxygen (HBO) and to monitor blood oxygen concentration during and following HBO therapy.
ANIMALS 8 healthy horses.
PROCEDURES In a randomized controlled crossover design study, each horse was exposed (beginning day 1) to 100% oxygen at a maximum of 3 atmospheres absolute (304 kPa) daily for 10 days or ambient air at atmospheric pressure in the HBO chamber for an equivalent amount of time (control). Bronchoalveolar lavage fluid samples were collected on days 0 and 10. After validation of candidate reference genes, relative mRNA expressions of various innate inflammatory, Th1 cell–derived, Th2 cell–derived (including eotaxin-2), Th17 cell–derived, and regulatory cytokines were measured by quantitative PCR assays. For 3 horses, arterial blood samples were collected for blood gas analysis during a separate HBO session.
RESULTS The optimal combination of reference genes was glyceraldehyde-3-phosphate dehydrogenase, hypoxanthine ribosyltransferase, and ribosomal protein L32. Compared with day 0 findings, expression of eotaxin-2 mRNA was significantly lower (0.12-fold reduction) and the percentage of neutrophils in bronchoalveolar lavage fluid samples was significantly lower on day 10 when horses received HBO therapy. Values of Pao2 rapidly increased (> 800 mm Hg) but immediately decreased to pretreatment values when HBO sessions ended.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that HBO therapy does not increase mRNA expression of inflammatory cytokines, but reduces eotaxin-2 mRNA transcription. The Pao2 increase was transient with no cumulative effects of HBO.