I don't know whether you have exhausted all options/2nd opinions etc but if not and you feel it worth another opinion/look at x-rays thena referral to Ian Wright at Greenwood Ellis may be worth a consideration http://www.newmarketequinehospital.com especially whilst he is still covered by insurance.
How is your horse now? Is there any improvement? Regarding strangles I witnessed a large outbreak a while back where a number of horses developed only a cough and snotty nose others also having a temperature, raspy breathing, swollen glands and lethargy and only a small number developed the...