They are all capable of explanation, if we admit the theory of telepathy, of a message sent by an unknown process from one living man's mind to another.

Where more than one person shares the vision, we may suppose that the influence comes directly from A to B, C and D, or comes from A to B, and is by him unconsciously "wired" on to B and C, or is "suggested" to them by B's conduct or words.
In that case animals may be equally affected, thus, if B seems alarmed, that may frighten his dog, or the alarm of a dog, caused by some noise or smell, heard or smelt by him, may frighten B, C and D, and make one or all of them see a ghost.
Popular opinion is strongly in favour of beasts seeing ghosts.

The people of St.Kilda, according to Martin, held that cows shared the visions of second-sighted milk-maids.

Horses are said to shy on the scene of murders.

Scott's horse ran away (home) when Sir Walter saw the bogle near Ashiestiel.