This section is from the book "The Gardener's Monthly And Horticulturist V23", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
In the August number, page 248, under the head of "Kalmia latifolia poisonous," you ask for conclusive proof on the subject.
In the course of conversation with a friend in Alabama (who, by the way, is a very intelligent gentleman and a great hunter), he told me that last winter he lost one of his best hounds from eating the entrails of a deer that they had recently killed, the deer having eaten the leaves of the Kalmia. He said that when there is snow on the ground the deer eat the Kalrnia leaves which do not seem to hurt them, but the hunters have to be careful that the dogs do not get the entrails to eat, for if so, it makes them very sick, and frequently proves fatal to them. This is not conclusive proof, but it is a straw.