RAO, recurrent airway obstruction, has nowadays become an increasing problem for our horses, resulting from incompatible needs of man and horse. Keeping horses under bad management within adequate supply of freshair and dusty bedding poses a frequent predispostion for the development of pulmonary dysfunction.
RAO is a chronic small airway inflammation caused by constant antigenic irritation and leading to mucosal hyperreactivity, loss of mucociliary clearance and bronchoconstriction resulting in increased airway resistance and a reduction in lung elasticity (compliance). This leads to prolonged exspiration and alveolar hypoventilation, expressed in hypoxemia and hyperkapnia.
Affected horses show a reproducable number of clinical symptoms which vary depending on these verity of the condition. The clinical picture ranges from minor signs like coughing especially when starting to work and minor exercise intolerance to more pronounced symptoms such as increased respiratory rate at rest, respriation facilitated by the abdominal muscles and changes observed by auscultation.
Therapy shoud primarily be aimed at improving management. A paper by THOMSON u. MC PHERSON (1984); DERKSEN et al. (1985); ARMSTRONG et al. (1986); BROADSTONE et al. (1988) points out that horses suffering from RAO ceased to show clinical symptoms when removed from their environment and resumed to show significant symptoms again when being brought back to the same.
For medication the use of expectorants and bronchodilators has proved useful.
Feed supplements based on plants to support lung function are in increasing demand from horse owners. One such product named Cirotex liquid® is marketed by NutriLabs (Nutritional Laboratories, Monmouth, UK) and was used for this trial. It is a plant based feed supplement for horses providing micronutrients mean to act specifically on the lung. The liquid concentrate consists of traditional pulmonary herbs, secondary plant ingredients and essential oils. Anecdotic reports suggest a positive influence on impaired lung function and a reduction of mucous production.
The hypothesis of our study was the question whether the application of Cirotex liquid® can result in a significant reduction of airway resistance.
For this trial 6 horses suffering from RAO were measured twice a week for 4 weeks under standardised conditions by forced oscillometry, in total measuring 5 cycles, each at frequencies of 1 Hz, 2 Hz, 3 Hz, 5 Hz and 7 Hz and followed by calculation of mean impedance values (excluding measurements with a coherence of less than 80 %). The differences between resistance values measured on the various days were compared and checked for significance (p ≤ 0,05).
In week 2 and 3 the horses received Cirotex liquid® at the manufacturer‟s recomended dose.
Measurements 1, 2 and 3 were summarised as pre-treatment. Measurements 4 and 5 were summarised as treatment. Measurement 6 was performed at the end of the treatment period with Cirotex liquid® and measurements 7, 8 and 9 were summarised as post-treatment.
The mean values were significant in relation to supplementation with Cirotex liquid® measured on 1 Hz, 2 and 3 Hz. The hypothesis for this trial suggesting a reduction of airway resistance in horses suffering from RAO was confirmed: a significant reduction in airway resistance was achieved. The changes of statistical significance were measured at frequencies relevant for the bronchioles.