dogs such as bulldogs and pugs are 17 times more at risk of heatstroke, hew research has warned. The “brachycephalic” breeds have a small skull and short nose – which stop them panting to cool off – and should not be kept in the sun for long spells, say British scientists.An analysis of the clinical records of more than 900,000 dogs across the UK identified the alarming phenomenon.The Chow Chow, once owned by legendary Mongolian leader Genghis Khan, is most vulnerable.It is 17 times more likely to suffer heatstroke than a Labrador retriever, traditionally Britain's favourite.This was followed by the bulldog (x14), which has an extremely flat face, and the French Bulldog (x6).Then came the Dogue de Bordeaux (x5) and the Cavalier King Charles.