This is an irregular reception or distribution of nervous power--a convulsive involuntary twitching of some muscle or set of muscles. It is an occasional consequence of distemper that has been unusually severe or imperfectly treated, and sometimes it is seen even after that disease has existed in its mildest form. [This nervous affection, more commonly known as St. Vitus' dance, is not a rare disease, and we doubt not that examples of it have been seen by most of our readers, more particularly in young dogs affected with distemper. This malady is characterized by sudden involuntary twitchings of the different muscles of the body, the disease being sometimes confined to one limb, sometimes to two, and frequently pervades the whole system, giving the dog a distressing and painful appearance. These involuntary motions, it is very true, are generally restricted during sleep, although in old chronic cases of long standing they often continue in full activity without any remission whatever. The disease is not attended with fever, and all the functions generally remain for a considerable time unimpaired.--L.] It first appears in one leg or shoulder, and is long, or perhaps entirely, confined to that limb. There is a singular spasmodic jerking action of the limb. It looks like a series of pulsations, and averages from forty to sixty in a minute. Oftener, perhaps, than otherwise, both legs are similarly affected. When the animal is lying down, the legs are convulsed in the way that I have described, and when he stands there is a pulsating depressing or sinking of the head and neck. In some cases, the muscles of the neck are the principal seat of the disease, or some muscle of the face; the temporal muscle beating like an artery; the masseter opening and closing the mouth, the muscles of the eyelid, and, in a few cases, those of the eye itself being affected. These convulsive movements generally, yet not uniformly, cease during sleep, but that sleep is often very much disturbed. If the case is neglected, and the dog is in a debilitated state, this spasmodic action steals over the whole frame, and he lies extended with every limb in constant and spasmodic action. In the majority of cases, such an expenditure of nervous and muscular power slowly destroys the strength of the animal, and he dies a mere skeleton; or the disease assumes the character of epilepsy, or it quiets down into true palsy. In the most favourable cases, no curative means having been used, the dog regains his flesh and general strength; but the chorea continues, the spasmodic action, however, being much lessened. At other times, it seems to have disappeared; but it is ready to return when the animal is excited or attacked by other disease. In a variety of instances, there is the irritable temper which accompanies chorea in the human being, and most certainly when the disease has been extensive and confirmed.