just recently our 16.2 warmblood mare has started to cough when trotting or cantering of course we pull up immediately. She is fine walking but as soon as asked to do anymore she sets off but then throws her head down with a hard dry cough. With weather not been riding much but our fields are a mass of hills so she is not out of condition and also has not been coughing when stabled and nothing is coming out when she does cough. I suspect it could be hay which is quite dusty we normally mix hay and hayledge but am going to try her just on hayledge see if any difference next week. Its such a shame as she loves to have a little canter and leave me and my hairy cob trailing behind. Any suggestions would be welcome