Does Marshall work??..just thought, do you have stables, or friends with animals who have byres?..take him they do not need to be shown and let him do some ratting...they do not eat them just kill them ...Tessa drops them in a pile at your feet (I am usually on top of a fence screaming!!!), but that was something else she started working ....just make sure that if he gets a bite from a rat he has had his injections....(Tessa has never been bitten_) but over the years she has killed thousands, or do you know of a piggery near you?...always rats wheres there is livestock....just a thought, they are wee dogs but were originally bred for hunting and this has stayed through the years in their genes

Marshall has started something for whatever reason and now it has became a habit...JRT's fixate on things...as you must know!!!!, we had a while where Tessa would jump literally about three feet off the ground and BARk into peoples faces, then run round them and do the same and then start to whizz around the room at silly speeds, now apart from 'is your dog ok?' 'is she going mad?' no-one ever said why!!, we started that the minute she went to do it  - taking a pull toy and encouraging her to pull one end while we tugged back, and after a while....it does not happen instantly...she would begin to go 'jump' and we said TOY! and she would get it and drop it at your feet and then play, it is not easy, it takes you think at the time  -for ever  - but eventually it became a new habit....I feel like acting like a dog with distemper....I grab the toy have some fun with Mum and thats it finished with!!!. Good Luck Jacks are notrious that when they get something into their little heads and overactive brains it takes time, patience and little bit of intervention from him upstairs!! lol Good Luck  Pat still alive after thirteen years with one!!!!!!

Have you tried an obedience class?  I know this sounds silly, but beings he is a high drive breed, maybe he is bored?  Or has developed this "alternative" to being bored a while ago and now it is comfortable.  When he exhibits this behavior, try a collar and leash and some commands, not just known ones, but work him on new things.  If he is working with you, he can't possibly chase his tail at the same time.

No expert here, just a thought.  Maybe a call into a behaviorist would be warranted?

We just saw a show on animal planet about this.. something about how we've inadvertantly bred in qualities, such as OCD.  They didn't offer any suggestions on how to fix the tail chasing, but it looked like they were actually working with a therapist.  The particular dog they showed would chase his tail to the point he'd get sick or even pass out.. and then start all over again. 

That may not be Marshalls issue at all (ocd).. hope you are able to find something to help.. I imagine if it's driving you all crazy it must make him a little nutsy too. 

Oh goodness...I'm sorry I don't know what to tell you but maybe Aunt Tina (Aussiebelts) would have some tips for you!