Rabbit with startling reaction to petting

Question

Bunny   I have a twelve year old male dwarf mix I have owned his entire life, and today he exhibited an extremely unusual and upsetting behavior and am trying to identify the source of the problem.  In this last year, he has developed the habit of, when scratched or pet on his middle or lower back, he will begin to vigorously lick either your hand, his chest, or whichever one of his hips your hand is closest to.  

This was not particularly disconcerting in itself -he is very old and I figured he liked getting pet in places that were possibly becoming difficult to groom.  

But then, this morning when I went out to visit him, I gave him a little scratch just behind his shoulder blades and something very disturbing happened.  His entire body stiffened, he whipped his head around to one of his hips, began licking at it in an almost panicked state, and then almost all at once his muscles locked up and he fell on his side, twisted in that position.  Then he began trembling violently and writhing, twisting over himself and rolling in his bedding in a twisting yet stiff manner, his muscles still locked and his head bent awkwardly.  This was very upsetting to me, and I had no idea how to help him so I didn't touch him other than to stabilize him when he appeared to try and pull himself free of the spell. This twisting and trembling continued for at least a minute and then his muscles seemed to relax some.  Then for another minute he lay on his side, eyes almost closed and breathing very hard.  In the whole incident he made no sound other than maybe a quiet grunt.  After laying there for several moments, he slowly came back to himself in jerky, sudden spurts.  First, he roused himself, then, after catching his breath for a few moments, picked himself up.  After that, he groomed his chest and hip a little more, and then just sat there.

My first thought was that he was getting torticollis (his brother, which we also had for many years had a stroke and got this, but recovered), and then I thought he must be dying, but he didn't die.  I could not tell if he was in any great pain afterwards, but I didn't want to handle him lest I get such a reaction again, so I lifted his house (which he sat inside) out of the cage and set it on the ground to see if he was at least well enough to move.  He was able to move, and hopped several feet from his house.  All his limbs seemed in working order -he didn't limp or labor over moving, and he was able to travel in a straight line, but he didn't go very far at a time.  He mostly taking two or three hops and then rested.  He wasn't lethargic, but he was definitely tired from his episode.

Afterwards, I felt brave enough to pick him up and took him inside so I could observe him for the rest of the day.  Lifting him up did not cause another episode, and I didn't observe one during his time indoors, either.  He acted fairly normal while inside, and when I took him back to his cage some hours later, he ate some of his food, so he is eating and drinking (I had filled his bottle right before all this happened).

Do you have any idea what might be afflicting him, and what I might be done to help him?

A little background on his care is that he lives in a well bedded outdoor hutch, eats a mainly pelleted diet (with treats of hay, dandelions, bananas and apples on occasion), and frequently is given free run of the yard for exercise. In extreme cold or wet weather he is brought indoors, and in hot weather he is kept in a cool, shady location or given a brief bath.
He is a very healthy, sociable, content bunny, and loves to be handled and pet all over.  He is very active for his age, and keeps himself very well groomed and clean.  He has a healthy appetite.  He regularly gets handled and given attention and also has the company of two other male rabbits, though they are all kept in separate cages.  

I've attached a picture of him.

Thank you for taking the time to read this.

Answer
Dear Tyra,

I am sorry for the delay, which was due to a sad death in my family.  Everything else sort of got put on hold.

That is certainly an odd reaction for your bunny to have had.  I can only suspect that at his age he may have some cryptic neurological problems that have not fully surfaced.  I do know that extreme itching can elicit seizures, and the cause of such itching can range from a stroke to a tumor to...unknown!  I suppose it is possible that your scratching his itch caused the equivalent of an overload to his nervous system, and he just keeled over.

Itching is believed to be a subset of pain (areas that are insensitive to pain cannot itch), and scratching can be such a relief that the whole body undergoes a change in physiology.

Whatever this was is not common, but I suspect it may have to do with his age.  You might want to take him to a rabbit-savvy vet for a wellness exam.  For now, you might want to limit your scratching to gentle stroking, to avoid eliciting such an intense, over-the-top reaction.

I hope he will be fine from this point on.

Dana