I can't find the original article at the moment, but this article (http://www.telegraph.co.uk/news/worldnews/ebola/11152482/Can-dogs-carry-Ebola.html) cites a 2005 study that mentions the dog risk:
A study published in 2005 pointed to a theoretical risk that dogs could pass the Ebola virus to humans through urine, faeces or saliva, but there is no evidence of this ever having happened, virologists said on Thursday.
And every scientist knows that the absence of evidence is NOT evidence of absence.
Just because something has not been studied, peer reviewed, and published, does not mean it does not exist.