08/03/2010 Horse Trust-Funded Research Leads To New, Non-Invasive Ways of Assessing Respiratory Health in Horses

A research project funded by equine charity The Horse Trust has developed and validated two simple techniques that can be used to monitor respiratory problems in horses and ponies.

These techniques could potentially be used by vets to screen for horses with respiratory problems and to assess whether a horse being treated for a respiratory condition is improving. They could also be used by pharmaceutical companies when trialling new treatments for respiratory conditions, such as Recurrent Airway Obstruction (RAO).

Respiratory problems are common in horses, with various surveys reporting that respiratory airway inflammation occurs in between 10 and 50 percent of competition and pleasure horses. Respiratory problems not only reduce the quality of life of the horse, but are also a common cause of exercise intolerance.

At present, the only techniques available to monitor respiratory inflammation are invasive, such as endoscopy. Due to being invasive, these techniques cannot be used frequently, so vets have had no way of objectively assessing whether a particular respiratory treatment or management technique is working.

But research that was given funding by The Horse Trust has developed two simple, non-invasive techniques to enable vets to monitor the severity of respiratory inflammation in horses. Both techniques are well tolerated by horses and ponies and can be used safely and ethically on repeated occasions.

"We are delighted that the research we have funded has led to new, non-invasive ways of monitoring respiratory inflammation in horses. These techniques could have a major impact on horse welfare by improving the diagnosis and treatment of this common condition," said Paul Jepson, Chief Executive and Veterinary Director of The Horse Trust.

The research, which was led by Professor Sandy Love¹ at the University of Glasgow, has developed a technique that allows vets to easily monitor the frequency of coughing in a horse over a long period of time with 100% sensitivity and 100% specificity.

Cough frequency is known to be a sensitive index of respiratory inflammation, but manually monitoring the number of coughs for an hour each day is not cost-effective. Love discovered that a digital recorder attached to a horse’s headcollar could be used to gather data, which could then be quickly analysed – one hour of coughing could be analysed within three minutes by manually examining a graph of the audio file. This analysis time could be speeded up further in a commercial setting by automating the analysis using computer software.

The audio file analysis was found to be 100% sensitive and specific – picking up every cough and perfectly distinguishing coughs from other noises, such as the horse stamping its feet, or a tractor starting.

The Horse Trust-funded research has also led to the development of a device – constructed using components readily available from a DIY store – that can be attached to a horse’s head to capture its breath and condense the liquids within the expired air. This device was used to analyse whether any of the substances in exhaled breath could be used as indicators of respiratory inflammation.

Love found that the most useful indicator was the pH of the liquid condensed from the expired breath – the pH of the exhaled breath condensate was higher in horses suffering from respiratory inflammation. He also monitored the level of various gases within the expired breath – carbon monoxide, nitric oxide and ethane – but found no significant correlation with respiratory inflammation.

“Both of these techniques could easily be commercialised to enable vets to quickly and ethically monitor respiratory inflammation in horses,” said Love. “They could also result in improved treatment of respiratory conditions, as vets will be able to objectively assess which treatments work or don’t work for a particular horse.”

For more information on The Horse Trust and its research programme, contact Susan Lewis at The Horse Trust, on 01494 488464 or susan@horsetrust.org.uk

Love et al's research project started in August 2006 and is ongoing. The research team recently submitted a paper entitled "The measurement of exhaled breath condensate pH in horses" to The Veterinary Journal. They have also submitted a paper entitled "Validation of a method for the objective assessment of coughing in horses" to Research in Veterinary Science.

¹Professor Sandy Love BVMS PhD MRCVS is the Professor of Equine Clinical Studies at the University of Glasgow and is Director of the Weipers Centre Equine Hospital.

The research team includes Kris Hughes, Tim Parkin, Marco Duz, Mike Cathcart and Andrew Whittaker. Previous breath analysis projects have involved Cathy Wyse, David Murphy, David Sutton and Dominic Mellor.