Effect of corticosteroid and bronchodilator therapy on bronchoalveolar lavage cytology following intrapulmonary blood inoculation.
BACKGROUND
Intrapulmonary blood causes an inflammatory response. Modifying this inflammatory response may be useful in the treatment of exercise induced pulmonary haemorrhage (EIPH).


OBJECTIVE
To evaluate the efficacy of 3 treatments, an oral bronchodilator, inhaled steroid and oral steroid in modifying the cellular response to intrapulmonary blood inoculation.


METHODS
Experimental design was a randomised block divided into 4 experimental segments of 2 weeks. Eight normal horses were randomly assigned to pairs and treatments. Autologous blood was inoculated into the lungs on 4 occasions over an 8 week period. For each treatment, a bronchoalveolar lavage (BAL) sample was collected on Day 0 and then 2 randomly selected segmental bronchi (one in each lung) were inoculated with blood (50 ml). BAL fluid was collected from one inoculated bronchus on Day 3 and from the other on Day 10. From BAL samples, total RBC and total and differential WBC were determined. Results for percentages and absolute cell counts were expressed as mean +/- s.e. and analysed using one, 2 and 3 way analysis of variance.


RESULTS
All treatments significantly reduced the number of erythrophages at Day 3 (P = 0.02) Treatment with oral prednisolone resulted in a significantly higher percentage of macrophages (P = 0.03) and also reduced the relative and absolute number of haemosiderophages in BAL compared to the other 2 treatments at Day 10 (P = 0.07).


CONCLUSIONS
We concluded that treatments altered the dynamics of cell populations in BAL following blood inoculation. Whether this alters the evolution of lung lesions following episodes of EIPH and indeed whether there are benefits for equine lungs following episodes of EIPH, remain to be determined.


CONCLUSIONS
Future studies into treatments for EIPH may benefit from incorporating a variety of dose rates for oral prednisolone and a longer period of evaluation. Such studies may also benefit from the use of cell activation markers. The concomitant use of pulmonary function testing and cytology in the field may assist in ascertaining whether treatments influence the performance and welfare of athletic horses subsequent to episodes of EIPH.
Walker
H J
HJ
University of Sydney, New South Wales, Australia.
Evans
D L
DL
Slocombe
R F
RF
Hodgson
J L
JL
Hodgson
D R
DR
D000704:Analysis of Variance; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology*; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004906:Erythrocyte Count / Q000662:veterinary; D005260:Female; D006470:Hemorrhage / Q000188:drug therapy / Q000517:prevention & control / Q000662:veterinary*; D006734:Horse Diseases / Q000188:drug therapy* / Q000517:prevention & control; D006736:Horses; D007958:Leukocyte Count / Q000662:veterinary; D008171:Lung Diseases / Q000188:drug therapy / Q000517:prevention & control / Q000662:veterinary*; D008297:Male; D011239:Prednisolone / Q000627:therapeutic use; D011652:Pulmonary Circulation
D000893:Anti-Inflammatory Agents; D001993:Bronchodilator Agents; D011239:Prednisolone