"Can it also help animals with Cushing’s?"
I am not aware of clinical studies addressing this issue. Cushing’s disease is the result of overstimulation of the adrenal glands from too much hormonal stimulation coming from the brain. This is most often the result of a tumor in the pituitary gland. Medicinal cannabis may be of some help in reducing the discomfort of the resulting symptoms, but is unlikely to have a strong enough effect on this problem to be of direct benefit.
While Cushing’s disease is more common in dogs than it is in humans, the basic principles of the condition are the same. I agree with Dr. Elkind in that cannabis is unlikely to have a specific positive effect on dogs with Cushing’s disease.