Heaves is known as a disease that can leave a horse struggling to breathe, ending athletic careers and even rendering a pleasure horse unsuitable for riding. Commonly known today as equine asthma, it’s an irreversible disease brought on by repeated exposure to dust and moulds. Ontario Veterinary College researcher, Dr. Dorothee Bienzle has a long history of primary and collaborative work studying asthma in horses. Her most recent contributions include working with a group of researchers in Slovenia, investigating stem cells as a potential treatment option.
Dr. Bienzle explains the usual causes of heaves are long term exposure to dusty or mouldy hay, bedding, dusty environments and sometimes even grass in hot humid climates that provide the right conditions for mould to thrive. “Horses get sensitized to these components in the inhaled air and with time, they develop airway inflammation and that begins to manifest with occasional coughing or runny nose.”
With continued exposure to the same particulates, the condition worsens, and the coughing becomes more continuous. The nose may be running and then there is thickening of the bronchial wall in the lung. There is extra smooth muscle being laid down and it becomes hard for the horse to exhale against mucus and inflammatory cells in the lumen of the airway.
The potential to downregulate inflammation with a biologic therapy like stem cells versus traditional drugs, like corticosteroids is clearly attractive. For administration of treatment, Bienzle explains there are already well-developed methods for examining the lower airway using endoscopes. Administering stem cells using this targeted method may be an appealing option versus intravenously where it is uncertain where the treatment ends up.
When explaining the challenges and expertise required to produce stem cells, Bienzle says, “This is not for the casual investigator because it takes some experience to have the right culture conditions to make sure those cells are clean. They are not cultured for very long, and when the final preparation is administered to an animal, it must be free of cell culture components that could make inflammation worse.”