Always, between dissimilar entities...humans/dogs, etc...there is room for 'doubt' that communication is genuine. However, the ability to communicate 'telepathically' is well documented and many books have been written. I do not doubt at all the capability to communicate telepathically, and find your experience very interesting. I do tend to be a bit...well, maybe 'a lot'...skeptical of such things when presented as TV programming, but then, I consider everything on TV as 'paid for, fictional entertainment' and wouldn't be surprised to find that it was faked by paid actors/actresses.
Hopefully, your foster will fully recover from all that ails her.