Myoclonus is common in older Cavaliers. The main symptom is jerking or nodding of the head and front legs when standing or sitting. Generally it doesn’t seem to worry the dog, although sometimes the jerking becomes so pronounced that the dog may fall over and can look distressed and disoriented.
Myoclonus is caused by small electric shocks in the underneath of the brain that momentarily disrupt the neurons. If the resulting jerks of the head are not strong enough to upset the dog, no medication is required; however, if stronger jerks cause distress, a drug such as Levetiracetam can be very helpful. Generally, however, myoclonus is not a condition that requires treatment; it should be regarded simply as a painless sign of old age in Cavaliers.