ecoli in dogs

I came across an article on a web site that mentioned breifly that ecoli could be transmitted to dogs through cat feces. Last year we had 9 dogs die in 2 weeks. It was all very sudden. I thought somehow they had been poisoned maybe. At the time we emptied our cat boxes in the yard. Since that time we have not done so. Is it a valid fact that cat feces could cause ecoli in dogs?
Ann