Persistent twitching is most
commonly due to a disease called chorea. A
nervous involvement characterized by intermittent twitching of certain
muscles or a group of muscles, chorea is quite common. The ailment may
persist for months or years and, though it may occasionally contribute
to discomfort, the normal functions of the animal remain apparently
unaffected, and its longevity seems unimpaired.
The cause of the disease is obscure. Most cases seem to occur as an
aftermath of a severe attack of distemper. It may also be a symptom of
an inflammatory condition of the membranes that cover the nerves or
spinal cord, and it occasionally appears in the early stages of
rickets. Even the most exacting microscopic examination of the body
tissues, on post mortem, have failed to reveal specific, characteristic
manifestations of the disease complex, though anemia has been a pretty
The muscles of the head and legs are most commonly affected in chorea,
though the twitching may occur in any part of the body. In mild cases,
the spasmodic movements are most readily observed while the animal is
lying on its side. The spasms are often less marked while the animal is
asleep, and excitement may cause exaggeration of the symptoms.
Consciousness is not disturbed in cases of chorea. Diagnosis is based
on the history of the case, the lack of general symptoms and the
characteristic periodic movements.
Treatment of chorea is usually ineffective, and it is not often
attempted because results cannot be expected unless medication is
administered over long periods of time. Various tonic
preparations containing arsenic or iron compounds have occasionally
been used with indifferent results. Highly nourishing food should back
up any course of treatment.
In the above, chorea has been discussed in its pure form, that is,
where it is present in the otherwise normal animal. Very often chorea
arises as a complication of a severe attack of distemper at the height
of the disease. In such cases death almost invariably ensues.