The dogs dont get sick. The real question is whether they are contagious while they are dealing with the virus. I havent heard an answer to that yet.
I do not know that anyone has done the experiments to determine whether dogs that have Ebola are actually contagious. In principle, it is an easy enough experiment to design and carry out.
From what I have read..Texas A&M, that has one of the finest veterinary schools in the country is on this.
If there is a problem...they will know.