Suitability of reclaimed wood bedding for horses with recurrent airway obstruction ("heaves")

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Most Canadian horses housed indoors are bedded on wood by-products; either saw dust or wood shavings. Soiled bedding is removed by hand daily from stables, stored on farms, and eventually trucked and discarded in landfills. Generation of such non-recycled waste is a challenge for the horse industry. GreenScene Agritek is a company with a proprietary recycling process that transforms used horse bedding into cleaned and dried high quality bedding. The process entails refinement and extraction, and may be applied to used and re-used bedding up to 20 times. GreenScene Agritek has pioneered this process, and the bedding is being used on horse farms. Horses that are stabled in dusty environments are prone to develop an asthma-like condition called "heaves" or "recurrent airway obstruction" (RAO) from chronic inhalation of mold spores and dust. Spores and dust are most often associated with feeding hay and using straw for bedding, but may also be present in some types of wood-derived bedding. Although bedding recycled by GreenScene Agritek has been assessed for mold content, neither mold concentration nor the effect on horses with respiratory disease is known. At the University of Guelph we have a group of horses with chronic RAO that is readily exacerbated by exposure to poor quality bedding. In this proposal we seek funds for a collaborative university-industry study to 1) determine mold spore counts in recycled wood bedding; 2) test whether horses prone to develop heaves can tolerate being stabled on recycled wood bedding better than on straw. The study will proceed in three phases - 4 weeks on reclaimed wood bedding, 2 weeks of washout period, 4 weeks on straw bedding. Respiratory function will be determined at the beginning and end of phase 1 and 3. The degree and time to onset of RAO in each horse will be analyzed in relation to mold spore concentration and mold types in bedding. This information will be useful to assure lack of adverse health effects of a product that has great potential to reduce the environmental impact of the horse industry.