Head nodding is not deliberate but the dog is conscious and aware that it is happening, the best way to describe this is just like a nodding dog in car rear window. This is not epilepsy and I cannot stress this enough as too many bulldogs are diagnosed epileptic when it's nothing more than head nodding. No one really knows what causes it and it is very breed specific, but it is pretty widely accepted that it is stress, excitement or pain induced and could be linked to blood sugar levels. My personal theory is that due to the high pain threshold the bulldog has, it's an outward sign that something is not quite right, although it is also very common in dogs that have played hard and then gone to sleep to wake up head nodding. I've also found that once a dog has had a head nodding episode many of them will be prone to them in the future so anything slightly stressful, exciting or painful can trigger one. This crops up a lot in dogs that have recently been rehomed, the combination of new surroundings and the increased level of attention is the most probable cause.
Try to find a link between the nodding and a problem, some of the more common triggers include:
It is also common in pregnant bulldogs or in new mums and giving something sweet, ie: dextrose, glucose, icing sugar, honey etc is enough to halt the episode although often distraction will also. It can also occur in young males that are having their testosterone surge at around 9-10 months and may not occur again throughout his lifetime. You will find that most dogs which have episodes of head nodding will be more prone to them as they get older, especially if the dog suffers from arthritis or some other on going problem, for these dogs keep some glucose sweets handy, although we had an old girl who I swear could fake a head nod just for the sweet she got to stop it.